The Geography of Cardamom (Elettaria cardamomum M.) : The "Queen" of Spices – Volume 2 [1st ed.] 9783030544737, 9783030544744

This book catalogues the multi-scale impact of agronomy and economy on Cardamom, known as the “Queen” of spices. Cardamo

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The Geography of Cardamom (Elettaria cardamomum M.) : The "Queen" of Spices – Volume 2 [1st ed.]
 9783030544737, 9783030544744

Table of contents :
Front Matter ....Pages i-xxi
Introduction (Kodoth Prabhakaran Nair)....Pages 1-7
Cardamom Botany (Kodoth Prabhakaran Nair)....Pages 9-38
Cardamom Chemistry (Kodoth Prabhakaran Nair)....Pages 39-52
The Agronomy of Cardamom (Kodoth Prabhakaran Nair)....Pages 53-107
The Role of “The Nutrient Buffer Power Concept” in Cardamom Nutrition (Kodoth Prabhakaran Nair)....Pages 109-123
Cardamom Pathology (Kodoth Prabhakaran Nair)....Pages 125-163
Cardamom Entomology (Kodoth Prabhakaran Nair)....Pages 165-176
Harvesting and Processing of Cardamom (Kodoth Prabhakaran Nair)....Pages 177-192
Industrial Processing of Cardamom and Cardamom Products (Kodoth Prabhakaran Nair)....Pages 193-208
The Economy of Cardamom Production (Kodoth Prabhakaran Nair)....Pages 209-225
Pharmacological Properties of Cardamom (Kodoth Prabhakaran Nair)....Pages 227-243
A Peek into the Future of Cardamom (Kodoth Prabhakaran Nair)....Pages 245-251
Large Cardamom (Amomum subulatum Roxb.) (Kodoth Prabhakaran Nair)....Pages 253-280
False Cardamom (Kodoth Prabhakaran Nair)....Pages 281-290
Specification for Cardamom (Kodoth Prabhakaran Nair)....Pages 291-300
Back Matter ....Pages 301-352

Citation preview

Kodoth Prabhakaran Nair

The Geography of Cardamom (Elettaria cardamomum M.) The “Queen” of Spices Volume 2

The Geography of Cardamom (Elettaria cardamomum M.)

Kodoth Prabhakaran Nair

The Geography of Cardamom (Elettaria cardamomum M.) The ‘‘Queen” of Spices – Volume 2

Kodoth Prabhakaran Nair Villament G3 C/o Dr. Mavila Pankajakshy Malaparamba, Kozhikode, Kerala, India

ISBN 978-3-030-54473-7    ISBN 978-3-030-54474-4 (eBook) https://doi.org/10.1007/978-3-030-54474-4 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2020 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

I dedicate this book to my wife, Dr Pankajam Nair, a nematologist trained in Europe, who gave up her profession to take up the task of a home maker, our son Dr. Kannan, our daughter Engineer Sreedevi, our son-in-law Engineer Arvind, and our grand children, Heera, Maya and Prahlad, who constantly encouraged me in this assignment. I also dedicate it to the memory of Black and Charlie, our canine fleet, who while alive, were a tremendous source of joy to me.

A word of Appreciation

I am very pleased to acknowledge the very purposeful discussions that I have had with Ms. Margaret Deignan, Senior Editor and Publisher, Springer. She has been a constant source of guidance and encouragement during the finalization of this book project.

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Preface

Cardamom, popularly known as the “Queen” of spices, has an interesting history dating back to the Vedic period (ca. B.C. 3000) and is among the ingredients poured into the sacrificial fire during a Hindu marriage ceremony. Today, cardamom commands a leading position among spices of immense commercial importance and is finding its way into the dietary habits of millions around the world—even in Europe and North America as well as Japan, hitherto unaccustomed to its use. Cardamom use ranges from a simple dietary constituent to that of immense pharmacological benefits. Although beset with many problems, both agronomic and economic, it is certain that next to black pepper, cardamom will emerge as an important commercial spice in world trade. India was the world leader in cardamom production, but, starting in 1970, the country began to slide in both production and productivity. Guatemala took over as the leading cardamom producer, like what Vietnam could achieve in growing pepper. However, Guatemalan cardamom is of inferior quality, the same being the case with Vietnam pepper. Among the primary constraints of production, it is the absence of an ideal ideotype, as in the case of black pepper, that is the biggest constraint in enhancing productivity. An ideal ideotype must combine superior productivity traits with strong resistance capacity to the dreaded Katte disease, widespread in the South Indian state of Karnataka. Fertility management of cardamom is still rooted in textbook knowledge, but this book contains an exclusive chapter on the “nutrient buffer power concept” based on the author’s research, with specific reference to potassium as a major a source of nutrition for cardamom, as well as other plants in general, which is required in abundance for optimum cardamom production. The chapter details the author’s research with reference to cardamom production in the two most important cardamom-growing states of Southern India: Kerala and Karnataka. Malaparamba, Kozhikode, Kerala, India  Kodoth Prabhakaran Nair

ix

Acknowledgments

Ms. T. Metilda Nancy Marie Rayan, Project Manager, and her team, did a remarkable job in the book production, with diligence and conscientiousness, most remarkably demonstrated during the very difficult times of the COVID-19 pandemic. Ms. Neelofar Yasmeen, Editor, Book Production, lent prompt support in editorial matters. I owe them all a deep debt of gratitude in bringing out this book in such an excellent manner.

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Contents

1 Introduction����������������������������������������������������������������������������������������������    1 1.1 Historical Background of Cardamom ����������������������������������������������    2 1.2 Cardamom Production and Productivity: A Worldview�������������������    4 1.2.1 Cardamom Cultivation in Other Parts of the World��������������    5 References��������������������������������������������������������������������������������������������������    7 2 Cardamom Botany����������������������������������������������������������������������������������    9 2.1 Taxonomy�����������������������������������������������������������������������������������������   10 2.1.1 Type Species: Elettaria cardamomum (Linn.), Maton����������   10 2.1.2 Varieties��������������������������������������������������������������������������������   11 2.1.3 Fruit and Seed ����������������������������������������������������������������������   13 2.1.4 The Cardamom Powder��������������������������������������������������������   15 2.1.5 Growth, Flowering, and Fruit Set in Cardamom������������������   16 2.1.6 Palynology and Pollination Biology ������������������������������������   18 2.1.7 Fruit Setting��������������������������������������������������������������������������   19 2.1.8 Physiology of Cardamom ����������������������������������������������������   20 2.2 Crop Improvement����������������������������������������������������������������������������   22 2.2.1 Germplasm����������������������������������������������������������������������������   22 2.2.2 Genetic Variability in Cardamom ����������������������������������������   23 2.2.3 Genetic Upgradation of Cardamom��������������������������������������   24 2.2.4 Selection��������������������������������������������������������������������������������   25 2.2.5 In Vitro Conservation������������������������������������������������������������   33 2.2.6 Conclusions��������������������������������������������������������������������������   34 References��������������������������������������������������������������������������������������������������   34 3 Cardamom Chemistry ����������������������������������������������������������������������������   39 3.1 Biosynthesis of Flavor Compounds��������������������������������������������������   42 3.1.1 Sites of Synthesis������������������������������������������������������������������   42 3.1.2 Biological Function��������������������������������������������������������������   42 3.1.3 Early Biosynthetic Steps and Acyclic Precursors ����������������   42

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3.2 Industrial Production������������������������������������������������������������������������   43 3.2.1 History��������������������������������������������������������������������������������   44 3.2.2 Evaluation of Flavor Quality����������������������������������������������   45 3.2.3 Cardamom Oleoresins and Extract������������������������������������   48 3.2.4 Variability in Composition������������������������������������������������   49 3.2.5 Pharmaceutical Properties of Cardamom Oil��������������������   49 3.2.6 Fixed Oil of Cardamom Seeds������������������������������������������   49 3.2.7 Conclusions������������������������������������������������������������������������   51 References��������������������������������������������������������������������������������������������������   51 4 The Agronomy of Cardamom ����������������������������������������������������������������   53 4.1 Distribution ��������������������������������������������������������������������������������������   53 4.2 Climate����������������������������������������������������������������������������������������������   54 4.2.1 Temperature ����������������������������������������������������������������������   54 4.2.2 Rainfall������������������������������������������������������������������������������   54 4.3 Management Aspects������������������������������������������������������������������������   56 4.3.1 Planting Systems����������������������������������������������������������������   56 4.3.2 Kodagu Malay System ������������������������������������������������������   56 4.3.3 North Kanara System��������������������������������������������������������   56 4.3.4 Southern System����������������������������������������������������������������   57 4.3.5 Mysore System������������������������������������������������������������������   57 4.4 Establishing a Cardamom Plantation������������������������������������������������   57 4.4.1 Preparation of the Main Field��������������������������������������������   57 4.4.2 Spacing������������������������������������������������������������������������������   58 4.4.3 Methods of Planting����������������������������������������������������������   59 4.4.4 Weed Control ��������������������������������������������������������������������   64 4.4.5 Additional Field Operations����������������������������������������������   64 4.4.6 Replanting in the Plantation����������������������������������������������   65 4.4.7 Propagation������������������������������������������������������������������������   65 4.4.8 Propagation Through Seeds ����������������������������������������������   66 4.4.9 Seed Selection��������������������������������������������������������������������   66 4.4.10 Preparation of Seeds����������������������������������������������������������   66 4.4.11 Viability of Seeds��������������������������������������������������������������   67 4.4.12 Presowing Treatment of Seeds������������������������������������������   67 4.4.13 Nursery Site ����������������������������������������������������������������������   68 4.4.14 Seed Rate and Sowing�������������������������������������������������������   69 4.4.15 Mulching of Nursery Beds������������������������������������������������   69 4.4.16 Secondary Nursery������������������������������������������������������������   70 4.4.17 Manuring����������������������������������������������������������������������������   70 4.4.18 Overhead Shade ����������������������������������������������������������������   71 4.4.19 Irrigation and Drainage������������������������������������������������������   71 4.4.20 Weeding ����������������������������������������������������������������������������   71 4.4.21 Earthing Up������������������������������������������������������������������������   71 4.4.22 Rotation and Fallow in Nursery Site����������������������������������   72

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4.4.23 Paddy Fields as Nurseries��������������������������������������������������   72 4.4.24 Dry Nursery ����������������������������������������������������������������������   72 4.4.25 Polybag Nursery����������������������������������������������������������������   73 4.4.26 Cost of Raising Seedlings��������������������������������������������������   73 4.4.27 Age of Seedlings for Field-Testing������������������������������������   74 4.4.28 Seed Propagation and Its Disadvantages ��������������������������   74 4.4.29 Vegetative Propagation������������������������������������������������������   74 4.4.30 Rapid Clonal Nursery Technique��������������������������������������   75 4.5 Shade Management in Cardamom����������������������������������������������������   75 4.5.1 Ideal Shade Trees ��������������������������������������������������������������   76 4.5.2 Shade Requirements����������������������������������������������������������   77 4.5.3 Pest Outbreak in Relation to Shade ����������������������������������   79 4.5.4 Biorecycling����������������������������������������������������������������������   79 4.5.5 Water Requirements and Irrigation Management��������������   79 4.5.6 Irrigation Methods ������������������������������������������������������������   80 4.5.7 Sprinkler Irrigation������������������������������������������������������������   80 4.5.8 Drip Irrigation��������������������������������������������������������������������   83 4.5.9 Perfospray Irrigation����������������������������������������������������������   83 4.5.10 Contour Furrows Irrigation������������������������������������������������   83 4.5.11 Time and Frequency of Irrigation��������������������������������������   84 4.5.12 Water Harvesting����������������������������������������������������������������   84 4.6 Cardamom-Based Cropping Systems ����������������������������������������������   84 4.6.1 Sole Forest Versus Cardamom Intercropped Forest: Economics and Labor Utilization��������������������������������������   85 4.6.2 Mixed Cropping System����������������������������������������������������   85 4.6.3 Cardamom–Coffee Mixed Cropping ��������������������������������   88 4.6.4 Changes in the Rhizosphere Due to Mixed Cropping ������   89 4.6.5 Conclusions������������������������������������������������������������������������   90 4.7 Cardamom Nutrition ������������������������������������������������������������������������   90 4.7.1 The Cardamom Soils����������������������������������������������������������   91 4.7.2 Soil Reaction����������������������������������������������������������������������   91 4.7.3 Cation Exchange Capacity������������������������������������������������   92 4.7.4 Organic Carbon������������������������������������������������������������������   92 4.7.5 Soil Phosphorus ����������������������������������������������������������������   92 4.7.6 Soil Potassium��������������������������������������������������������������������   93 4.7.7 Secondary Nutrients and Micronutrients ��������������������������   93 4.7.8 Nutrient Deficiency Symptoms������������������������������������������   94 4.7.9 Shade Trees and Soil Fertility��������������������������������������������   94 4.7.10 Plant Nutrient Composition and Uptake����������������������������   95 4.8 Fertilizer Requirements��������������������������������������������������������������������   97 4.8.1 Scheduling Fertilizer Application��������������������������������������   97 4.8.2 Diagnostic Recommendation Integration System��������������  100 4.8.3 Method and Time of Fertilizer Application ����������������������  100 References��������������������������������������������������������������������������������������������������  102

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5 The Role of “The Nutrient Buffer Power Concept” in Cardamom Nutrition����������������������������������������������������������������������������������������������������  109 5.1 The “Buffer Power” and Its Effect on Nutrient Availability ������������  110 5.1.1 Basic Concepts������������������������������������������������������������������  110 5.2 Measuring the Nutrient Buffer Power and Its Importance in Affecting Nutrient Concentrations on Root Surfaces ������������������  111 5.3 Quantifying the Buffer Power of Soils and Testing Its Effect on Potassium Availability������������������������������������������������������������������  114 5.4 The Importance of Potassium Buffer Power Determination in Predicting Potassium Availability to Perennial Crops������������������  114 5.5 The Commercial Significance of the Potassium Buffer Power Determination in Potassium Fertilizer Management for Perennial Crops ������������������������������������������������������������������������������������������������  119 5.6 Conclusions��������������������������������������������������������������������������������������  120 References��������������������������������������������������������������������������������������������������  121 6 Cardamom Pathology������������������������������������������������������������������������������  125 6.1 Major Diseases����������������������������������������������������������������������������������  125 6.1.1 Capsule Rot (“Azhukal” Disease)��������������������������������������  126 6.1.2 Disease Management ��������������������������������������������������������  128 6.1.3 Biological Control of Diseases������������������������������������������  129 6.1.4 Rhizome Rot Disease��������������������������������������������������������  129 6.1.5 Leaf Blight Disease (“Chenthal” Disease)������������������������  131 6.2 Minor Diseases����������������������������������������������������������������������������������  133 6.2.1 Leaf Blotch������������������������������������������������������������������������  134 6.2.2 Disease Symptoms ������������������������������������������������������������  134 6.2.3 Causal Pathogen����������������������������������������������������������������  134 6.2.4 Phytophthora Leaf Blight ��������������������������������������������������  134 6.2.5 Disease Management ��������������������������������������������������������  135 6.2.6 Leaf Rust����������������������������������������������������������������������������  135 6.2.7 Leaf Spot Diseases������������������������������������������������������������  136 6.2.8 Sphaceloma Leaf Spot��������������������������������������������������������  136 6.2.9 Cercospora Leaf Spot ��������������������������������������������������������  136 6.2.10 Glomella Leaf Spot������������������������������������������������������������  137 6.2.11 Phaeotrichoconis Leaf Spot������������������������������������������������  137 6.2.12 Ceriospora Leaf Spot����������������������������������������������������������  137 6.2.13 Management of Leaf Spot Diseases����������������������������������  138 6.2.14 Sooty Mold������������������������������������������������������������������������  138 6.2.15 Stem Lodging��������������������������������������������������������������������  138 6.2.16 Anthracnose ����������������������������������������������������������������������  138 6.2.17 Causal Pathogen����������������������������������������������������������������  139 6.2.18 Capsule Tip Rot�����������������������������������������������������������������  139 6.2.19 Fusarium Capsule Disease������������������������������������������������  139 6.2.20 Capsule Canker������������������������������������������������������������������  139 6.2.21 Capsule Ring Spot�������������������������������������������������������������  140

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6.2.22 Erwinia Rot������������������������������������������������������������������������  140 6.2.23 Causal Pathogen����������������������������������������������������������������  140 6.2.24 Diseases of Cardamom Found in Nurseries����������������������  141 6.2.25 Disease Management ��������������������������������������������������������  142 6.2.26 Nursery Leaf Spot��������������������������������������������������������������  142 6.2.27 Leaf Spot in Secondary Nursery����������������������������������������  142 6.2.28 Conclusions������������������������������������������������������������������������  143 6.2.29 Viral Diseases of Cardamom ��������������������������������������������  143 6.2.30 Mosaic or Katte Disease (car-MV)������������������������������������  143 6.2.31 Distribution������������������������������������������������������������������������  144 6.2.32 The Extent of Crop Loss����������������������������������������������������  144 6.2.33 Symptomatology����������������������������������������������������������������  144 6.2.34 Transmission����������������������������������������������������������������������  145 6.2.35 Spread of the Disease��������������������������������������������������������  145 6.2.36 Etiology������������������������������������������������������������������������������  147 6.2.37 Strains of car-MV��������������������������������������������������������������  147 6.2.38 Cardamom Vein-Clearing Disease or “Kokke Kandu” (car-VCV)��������������������������������������������������������������������������  148 6.2.39 Importance of the Disease��������������������������������������������������  148 6.2.40 Extent of Crop Loss ����������������������������������������������������������  148 6.2.41 Symptoms of the Disease��������������������������������������������������  149 6.2.42 Transmission and Etiology of the Disease������������������������  149 6.2.43 Spread of the Disease��������������������������������������������������������  149 6.2.44 Cardamom Necrosis Disease (Nilgiri Necrosis Disease)��  150 6.2.45 Importance of the Disease��������������������������������������������������  150 6.2.46 Symptomatology and Crop Loss����������������������������������������  150 6.2.47 Transmission of the Disease����������������������������������������������  151 6.2.48 Etiology and Epidemiology ����������������������������������������������  151 6.2.49 Infectious Variegation��������������������������������������������������������  151 6.3 Integrated Management of Viral Diseases in Cardamom�����������������  152 6.3.1 Production and Use of Virus-Free Planting Material��������  152 6.3.2 Avoidance of Volunteers����������������������������������������������������  152 6.3.3 Movement of Planting Material ����������������������������������������  153 6.3.4 Vector Management ����������������������������������������������������������  153 6.3.5 Development of Katte-Resistant Cardamom ��������������������  156 6.3.6 Conclusions������������������������������������������������������������������������  157 References��������������������������������������������������������������������������������������������������  158 7 Cardamom Entomology��������������������������������������������������������������������������  165 7.1 Major Pests����������������������������������������������������������������������������������������  165 7.1.1 Cardamom Thrips [Sciothrips Cardamomi (Ramk)] ��������  165 7.1.2 Panicle/Capsule Shoot Borer (Conogethes Punctiferalis Guen)����������������������������������������������������������������������������������  167 7.1.3 Whitefly [Kanakarajiella cardamomi (David and Subr.) David and Sundararaj]������������������������������������������������������  169 7.1.4 Hairy Caterpillars��������������������������������������������������������������  170

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7.2 Minor Pests�������������������������������������������������������������������������������������  171 7.2.1 Capsule Borers������������������������������������������������������������������  171 7.3 Storage Pests ����������������������������������������������������������������������������������  173 7.4 Conclusions ������������������������������������������������������������������������������������  174 References��������������������������������������������������������������������������������������������������  174 8 Harvesting and Processing of Cardamom ��������������������������������������������  177 8.1 Harvesting ��������������������������������������������������������������������������������������  177 8.1.1 Time and Stage of Harvesting ������������������������������������������  177 8.2 Curing����������������������������������������������������������������������������������������������  181 8.2.1 Sun Drying������������������������������������������������������������������������  182 8.2.2 Artificial Drying����������������������������������������������������������������  182 8.2.3 Bin Dryer��������������������������������������������������������������������������  182 8.2.4 Melccard Dryer ����������������������������������������������������������������  183 8.2.5 Cross-Flow Electric Dryer������������������������������������������������  183 8.2.6 Solar Cardamom Dryer ����������������������������������������������������  183 8.2.7 Mechanical Cardamom Dryer ������������������������������������������  183 8.2.8 Through-Flow Dryer ��������������������������������������������������������  184 8.2.9 Bleached Cardamom ��������������������������������������������������������  184 8.3 Moisture Content����������������������������������������������������������������������������  185 8.4 Grading��������������������������������������������������������������������������������������������  185 8.5 Bleached and Half-Bleached Cardamom����������������������������������������  187 8.6 Commercial Cardamom Grades in Sri Lanka ��������������������������������  190 8.7 Grading and Packing ����������������������������������������������������������������������  190 8.8 Conclusions ������������������������������������������������������������������������������������  191 References��������������������������������������������������������������������������������������������������  191 9 Industrial Processing of Cardamom and Cardamom Products����������  193 9.1 Cardamom Seeds����������������������������������������������������������������������������  194 9.2 Packaging and Storage of Cardamom Seeds����������������������������������  194 9.3 Cardamom Powder��������������������������������������������������������������������������  195 9.4 Grinding������������������������������������������������������������������������������������������  195 9.5 Storage Powder ������������������������������������������������������������������������������  196 9.6 Cardamom Oil��������������������������������������������������������������������������������  197 9.7 Industrial Production of Cardamom Oil������������������������������������������  198 9.8 Improvement in Flavor Quality of Cardamom Oil��������������������������  199 9.9 Storage of Cardamom Oil ��������������������������������������������������������������  200 9.10 Cardamom Oleoresin����������������������������������������������������������������������  200 9.11 Solvent Extraction��������������������������������������������������������������������������  201 9.11.1 Supercritical Carbon Dioxide Extraction of Cardamom��  202 9.11.2 Encapsulated Cardamom Flavor ��������������������������������������  203 9.12 Large Cardamom (Nepal Cardamom)��������������������������������������������  205 9.13 Other Products��������������������������������������������������������������������������������  205 9.14 Conclusions ������������������������������������������������������������������������������������  206 References��������������������������������������������������������������������������������������������������  207

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10 The Economy of Cardamom Production ����������������������������������������������  209 10.1 Emerging Trends in Cardamom Production ��������������������������������  212 10.1.1 Area ������������������������������������������������������������������������������  212 10.1.2 Production and Productivity������������������������������������������  212 10.1.3 Growth Estimates����������������������������������������������������������  213 10.1.4 Production Constraints��������������������������������������������������  214 10.1.5 Cost of Production��������������������������������������������������������  215 10.1.6 Domestic Market Structure and Prices��������������������������  216 10.1.7 Price Analysis����������������������������������������������������������������  216 10.2 Export Performance of Cardamom����������������������������������������������  217 10.3 Direction of Indian Export Trade��������������������������������������������������  218 10.4 India’s Competitive Position in the International Cardamom Market������������������������������������������������������������������������  219 10.5 Demand and Supply Pattern ��������������������������������������������������������  219 10.6 Model Identification����������������������������������������������������������������������  220 10.7 The Forecast����������������������������������������������������������������������������������  221 10.8 Demand����������������������������������������������������������������������������������������  221 10.9 Projections of Supply��������������������������������������������������������������������  222 10.10 Conclusions����������������������������������������������������������������������������������  224 References��������������������������������������������������������������������������������������������������  225 11 Pharmacological Properties of Cardamom ������������������������������������������  227 11.1 Pharmacological Properties����������������������������������������������������������  227 11.2 Carminative Action ����������������������������������������������������������������������  228 11.3 Antimicrobial Activity������������������������������������������������������������������  228 11.4 Anticarcinogenic Activity ������������������������������������������������������������  229 11.5 Anti-Inflammatory Activity����������������������������������������������������������  230 11.6 Other Pharmacological Studies����������������������������������������������������  230 11.7 Toxicity ����������������������������������������������������������������������������������������  231 11.7.1 Antioxidant Function����������������������������������������������������  231 11.7.2 Pharmaceutical Products ����������������������������������������������  232 11.8 Aromatic Cardamom Tincture (BPC, Tincture Cardamom Aromatic, Carminative Tincture) ������������������������������  232 11.9 Other Properties����������������������������������������������������������������������������  232 11.9.1 Effect on Stored Product Insect Pests ��������������������������  232 11.9.2 Effect of Cardamom on House Dust Mites ������������������  233 11.9.3 Cardamom in Traditional Systems of Medicine�����������  234 11.10 Cardamom as a Spice��������������������������������������������������������������������  235 11.10.1 The Pattern of Suitability for Cardamom����������������������  237 11.10.2 Spice Blend and Garam Masala������������������������������������  238 11.10.3 Cardamom Oil, Oleoresin, and Soluble Cardamom�����  240 11.11 Conclusions����������������������������������������������������������������������������������  241 References��������������������������������������������������������������������������������������������������  242

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12 A Peek into the Future of Cardamom����������������������������������������������������  245 12.1 Potential Applications ��������������������������������������������������������������������  248 12.2 Future Outlook��������������������������������������������������������������������������������  248 12.2.1 Research and Development��������������������������������������������  248 References��������������������������������������������������������������������������������������������������  251 13 Large Cardamom (Amomum subulatum Roxb.) ����������������������������������  253 13.1 Habit and Habitat����������������������������������������������������������������������������  254 13.2 Cultivars������������������������������������������������������������������������������������������  254 13.2.1 Ramsey ��������������������������������������������������������������������������  255 13.2.2 Sawney ��������������������������������������������������������������������������  255 13.2.3 Golsey (Dzoungu Golsey)����������������������������������������������  256 13.2.4 Ramla ����������������������������������������������������������������������������  256 13.2.5 Varlangey������������������������������������������������������������������������  257 13.2.6 Bebo ������������������������������������������������������������������������������  257 13.2.7 Seremna (Sharmney or Lepbrakey)��������������������������������  257 13.3 Plant Propagation����������������������������������������������������������������������������  258 13.3.1 Nursery Practices������������������������������������������������������������  258 13.3.2 Nursery Site Selection����������������������������������������������������  259 13.3.3 Plantation Management��������������������������������������������������  261 13.4 Plant Nutrition��������������������������������������������������������������������������������  262 13.4.1 Weeding��������������������������������������������������������������������������  263 13.4.2 Shade Regulation������������������������������������������������������������  263 13.4.3 Irrigation������������������������������������������������������������������������  263 13.4.4 Roguing and Gap Filling������������������������������������������������  264 13.5 Crop Improvement��������������������������������������������������������������������������  264 13.5.1 Flowering and Pollination����������������������������������������������  264 13.5.2 Genetic Investigations����������������������������������������������������  264 13.5.3 Clonal Selection ������������������������������������������������������������  265 13.6 Insect Pest Management ����������������������������������������������������������������  265 13.6.1 Leaf Caterpillar��������������������������������������������������������������  265 13.6.2 Nature and Extent of Damage����������������������������������������  265 13.6.3 Hairy Caterpillar������������������������������������������������������������  266 13.6.4 Aphids����������������������������������������������������������������������������  266 13.6.5 Shoot Fly������������������������������������������������������������������������  267 13.6.6 Stem Borer (Glypheterix Sp. (Lepidoptera: Glyphiperidae))��������������������������������������������������������������  267 13.6.7 White Grubs (Holotrichia Sp. (Coleoptera: Melolonthidae))��������������������������������������������������������������  268 13.6.8 Minor Pests��������������������������������������������������������������������  268 13.6.9 Other Pests����������������������������������������������������������������������  270 13.6.10 Storage Pests������������������������������������������������������������������  271 13.7 Diseases������������������������������������������������������������������������������������������  271 13.7.1 Chirke Disease ��������������������������������������������������������������  271 13.7.2 Foorkey Disease ������������������������������������������������������������  271

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13.8 Management of Chirke and Foorkey Diseases ����������������������������  272 13.8.1 Leaf Streak Disease������������������������������������������������������  272 13.8.2 Flower Rot��������������������������������������������������������������������  273 13.8.3 Wilt��������������������������������������������������������������������������������  273 13.9 Harvesting and Postharvest Technology��������������������������������������  273 13.9.1 The Bhatti System����������������������������������������������������������  274 13.9.2 Portable Curing Chamber����������������������������������������������  274 13.9.3 Flue Pipe Curing System����������������������������������������������  274 13.10 Natural Convection Dryer������������������������������������������������������������  275 13.10.1 Gasifier Curing System ������������������������������������������������  275 13.11 Chemical Composition ����������������������������������������������������������������  276 13.12 Properties and Uses����������������������������������������������������������������������  277 13.13 Conclusions����������������������������������������������������������������������������������  278 References��������������������������������������������������������������������������������������������������  278 14 False Cardamom��������������������������������������������������������������������������������������  281 14.1 Elettaria����������������������������������������������������������������������������������������  281 14.1.1 Aframomum Sp.������������������������������������������������������������  283 14.1.2 Amomum Sp. ����������������������������������������������������������������  286 References��������������������������������������������������������������������������������������������������  289 15 Specification for Cardamom ������������������������������������������������������������������  291 15.1 Requirements��������������������������������������������������������������������������������  291 15.1.1 Cardamom with Capsules ��������������������������������������������  291 15.1.2 Extraneous Matter ��������������������������������������������������������  292 15.1.3 Packing and Marking����������������������������������������������������  293 15.1.4 Specification for Large Cardamom ������������������������������  294 15.1.5 Requirements����������������������������������������������������������������  294 Research Highlights in Cardamom����������������������������������������������������������������  301 Efficacy of The Nutrient Buffer Power Concept in Cardamom Nutrition������  325 Research Innovations in Cardamom Production for Farmers’ Benefit������  335 References ��������������������������������������������������������������������������������������������������������  351

Chapter 1

Introduction

Abstract  The chapter discusses, at length, the historical background of cardamom, a global outlook of cardamom production. In the ancient Indian language Sanskrit, cardamom is referred to as “Ela.” The role of cardamom is discussed with reference to ancient Indian Vedic literature. Cardamom dates back to B.C. 3000. Keywords  “Queen” of spices · Ela · Vedic literature · Global cardamom production

Cardamom, popularly known as the “Queen of Spices” is the second most important spice crop in the world, next to black pepper (Piper nigrum), which is known as the “King of Spices.” The description “Queen of Spices” is apt, because cardamom has a pleasant aroma and taste and has been a highly valued spice since time immemorial. Cardamom belongs to the genus Elettaria and species cardamomum (Maton). The term Elettaria, which is the generic name, has its origin in the word Elettari (in Tamil, one of the popular South Indian languages), referring to the cardamom seeds. In the original description, it means a “particle/seed of the leaf.” Elettaria is a large-­ sized perennial herbaceous rhizomatous monocot that belongs to the Zingiberaceae family. The plant is extensively grown in the hilly tracts of southern India at elevations ranging from 800 m to 1500 m. It grows best as an under crop, beneath forest trees, in shade, and a cool climate at high elevations. The plant is grown in Sri Lanka, in Papua New Guinea (PNG), and in Tanzania, Africa. In Latin America, Guatemala is the biggest grower of cardamom. Indeed, Guatemalan cardamom is the biggest competitor to Indian cardamom in the world market.

© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2020 K. P. Nair, The Geography of Cardamom (Elettaria cardamomum M.), https://doi.org/10.1007/978-3-030-54474-4_1

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1 Introduction

1.1  Historical Background of Cardamom Cardamom has an interesting history dating back to Vedic times, about B.C. 3000. In the ancient Indian language Sanskrit, it is referred to as “Ela.” In ancient Hindu culture, sacrificial fire was a common ritual, and in ancient texts (Mahindru 1982), cardamom was an ingredient, along with several other materials, in the sacrificial fire, solemnizing a Hindu marriage. Both the Charaka Samhita and the Susrutha Samhita, the ancient Indian Ayurvedic texts, written in the post-Vedic period (B.C. 1400–B.C. 1600) mention cardamom. However, it is not known precisely whether cardamom, referred to as Ela in these texts, is the Indian variety or the large Nepalese variety. The Assyrians and Babylonians were familiar with medicinal plants, and cardamom was among the 200 or so plants that the former dealt with (Parry 1969). It was mentioned that Merodach-Baladan II (reigned B.C. 721– B.C. 702), the ancient king of Babylon, grew cardamom among other herbs in his garden. Surprisingly, there was no mention of cardamom in the ancient Egyptian texts, unlike their treatment of pepper. Possibly, cardamom was just beginning to reach Assyria and Babylonia through the land routes. Interestingly, cardamom is cited in some of the ancient Greek and Roman texts. Spices were the symbols of royalty and luxury, and cardamom was used in the manufacture of perfumes during Greek and Roman times. In addition, cardamom was used as an aphrodisiac (Parry 1969). Significantly, Dioscorides (40–90 A.D.), the Greek physician and author of the legendary Materia Medica, mentions cardamom in his work. Cardamom was widely used to aid digestion, and that was the most important reason both the Greeks and Romans imported the spice in large quantities from India. Thus, it became one of the most popular oriental spices in Greek and Roman cuisine. This achievement led to cardamom being listed as a dutiable item in Alexandria in 176 A.D. In his Journal of Indian Travels (1596), Linschoten describes two types of cardamom in use in southern India: the “greater” (large) and “lesser” (small) types. This would suggest that the large cardamom found extensively in Nepal must have been finding its way to southern India through land routes, brought by travelers dating back to nearly 4000 years from today. Referring to the introduction of cardamom to Europe, Dymock writes, “When they were first introduced into Europe is doubtful, as their identity with the Amomum and Cardamomum of the Greeks and Romans cannot be proved.” Linschoten writes about lesser cardamom that “it mostly is grown in Calicut and Cannanore, places on the coast of Malabar.” Paludanus, a contemporary of Linschoten, wrote that, according to Avicenna, there are two kinds of cardamoms, “greater” and “lesser,” and goes on to add that cardamom was unknown to Greeks personages such as Galen and Dioscorides. In his Seventh Book of Simples, Galen wrote, “cardamom is not so hot as Nasturtium or water cresses,” “but pleasanter of savor and smell with some small bitterness.” These properties were dissimilar to those of the Indian cardamom. In his First Book, Dioscorides, commenting on the cardamom brought from Armenia and Bosphorus, wrote, “we must choose that which is full, and tough in breaking, sharp and bitter of taste, and smell thereof, which cause heaviness in a man’s head” (Watt 1872). Obviously,

1.1  Historical Background of Cardamom

3

Dioscorides was writing not about Indian cardamom, but about a different plant. Such references led Paludanus (Watt 1872) to infer that the Amomum and Cardamomum of the ancient Greeks were not the spices of India. On the whole, references to cardamom in ancient and early centuries of the Christian era and even in the middle ages are but scanty compared with references to black pepper. Even Auboyar, in his classic work on day-to-day living in ancient India (B.C. 200 to 700 A.D.), makes only a fleeting mention of cardamom (Mahindru 1982). The Mediterranean merchants were clearly cheated by the Arabs on the sea route through which the latter brought home spices from India. Like pepper, cardamom was no exception. Pliny thought that cardamom was grown in Arabia. This belief persisted until the discovery of the sea route to India and the landing of the Portuguese on the west coast of India. The latter event coincided with the ending of the Arab monopoly on the spice trade, and the Portuguese started shipping out pepper, cardamom, and ginger to Europe. Since the European colonizers were more interested in procuring pepper and ginger, both crops took hold in India—the former in particular along the Malabar Coast. Cardamom was relegated to the back seat, a situation that lasted from the sixteenth to the eighteenth centuries. Cardamom was considered a minor forest produce. It was only at the beginning of the nineteenth century that cardamom plantations were established, but the spice was interplanted with coffee. Still, cardamom cultivation spread rapidly in the Western Ghats, and the region south of Palakkad (the midsouthern district of Kerala) came to be known as Cardamom Hills. The earliest written evidence that cardamom was being grown in India was in the records of the officers working for the British East India Company. The most important among these written pieces was that of Ludlow, an assistant conservator of forests. Others were the Pharmacographia, Madras Manual, and Rice Manual. A brief description of cardamom cultivation in South India was also given by Watt (1872). The system of cardamom collection from naturally growing plants continued until 1803, but demand escalated in later years, and this naturally led to the establishment of large-scale plantations in India and Sri Lanka, then known as Ceylon (Ridley 1912). Within the entire state of Kerala, in the two erstwhile states of Travancore and Cochin, which had their own kings, cardamom was a monopoly of the respective governments. The Raja (King) of Travancore mandated that all the cardamom produced be sold to his official representative and sent to a central depot in the central Kerala town of Alleppey, which was then a state port. Here, the produce was sold by auction. The principal buyers were Muslims, and the best lot, known as “Alleppey Green,” was reserved for export. In the forestland, in the state of Kerala, owned by the then British government, cardamom was considered a “miscellaneous produce,” while in the neighboring Coorg district in the state of Karnataka, forestlands were leased out to private cultivators of cardamom. In Leghorn, the conservator of forests in the Madras Presidency (an early nomenclature that included four southern states, namely, Kerala, Karnataka, Madras, and Andhra, which have all become independent since then), noted that the spread of coffee eclipsed that of cardamom in many areas of “Malabar Mountains”—a reference to the Western Ghats (Watt 1872). Cardamom cultivation is mentioned in the

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1 Introduction

Madras Manual, which states, “In the hills of Travancore cardamom grows spontaneously in the deep shades of the forests: it resembles somewhat turmeric and ginger plants but grows to a height of 6–10 ft and throws out the long shoots which bear the cardamom pods.” The following passage describes cardamom management: “The owners of the gardens, early in the season come up from the low country east of the Ghats, cut the brushwood and burn the creepers and otherwise clear the soil for the growth of the plants as soon as the rains fall. They come back to gather the cardamom when they ripen, about October or November” (Watt 1872). One can surmise from the writings of the British officials that a process of bleaching used to be carried out in Karnataka, and this was done by transporting cardamom to Havre, a place in the Dharma district of Karnataka, and the bleaching process used the water from a specific well, thereby enhancing the flavor of the dried product (Watt 1872). Mollison (1900) elaborately described a bleaching method in which soap nut water was used.

1.2  Cardamom Production and Productivity: A Worldview Currently, cardamom production is concentrated primarily in India and Guatemala. Cardamom was introduced to Guatemala in 1920, most likely from India or Sri Lanka, by a New York broker and was planted in the vicinity of Cobán in the department of Alta Verapaz (Lawrence 1978). After World War II, cardamom production in Guatemala increased substantially on account of a shortage in production and high prices, and Guatemala soon became the top cardamom producer in the world. Native Guatemalans do not relish the taste of cardamom, and the entire quantity produced is exported. Today, Guatemala produces about 13,000–14,000 t of cardamom annually. Table  1.1 presents a worldview of cardamom production and productivity. In India, the cardamom area has come down during the last two decades, from 1,05,000 ha in 1987–1988 to 69,820 ha in 1997–1998, a decrease of 33.5%. Still, production increased 190%, from 3200 t during 1987–1988 to 9290 t in 1999–2000. During the same period, productivity has risen from 47 to 173 kg ha−1, an increase of 268%. Cardamom cultivation is confined primarily to three South Indian states: Kerala, Karnataka, and Tamil Nadu. Kerala has 59% of the total area cultivated and contributes 70% of the total production. Karnataka has 34% of the total area cultivated and contributes 23% to total production, while Tamil Nadu has 7% of the area and contributes the same percentage to total production. Most of the cardamom-­ growing areas in Kerala are located in the districts of Idukki, Palakkad, and Wayanad. In Karnataka, the crop is grown in the districts of Coorg, Chikmagalur, and Hassan, and, to some extent, in North Kanara district. In Tamil Nadu, cardamom cultivation is located in certain places of Pulney and Kodai Hills. On the whole, in India, cardamom is a small-landholder’s crop, and there are 40,000 holdings covering an area of 80,000 ha (George and John 1998). The cardamom-­growing regions of South India lie within 8° and 30° latitude and 75° and 78° longitude. The

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1.2  Cardamom Production and Productivity: A Worldview Table 1.1  Cardamom production in the world Time span 1970/1971–1974/1975 1975/1976–1979/1980 1980–1981 1984–1985 1985/1986–1989/1990 1990/1991–1994/1995 1995/1996–1997/1998

Percentage share of total India Guatemala 65.4 21.5 53.7 34.5 42.9 48.8 31.9 60.3 26.5 67.5 28.4 65.6 29.8 64.2

Othersa 13.1 11.8 8.3 7.8 6.0 6.0 6.0

World production (mt)b 4678 6628 10,250 12,220 14,392 19,470 24,953

Source: Cardamom Statistics, 1984–1985, Cardamom Board, Government of India, Cochin, Kerala State. Spices Statistics, 1997, Spices Board, Government of India, Cochin, Kerala State. All India Final Estimate of Cardamom, 1997/1998, Government of India, Ministry of Agriculture Important note: In three decades, the percentage contribution of India to total production plummeted by 54%, while Guatemala’s increased by 199%. Other countries in the same period had a similar decline of 54%, like that of India; thus, Guatemala takes the leading position in cardamom production in the world a Estimates, actual figures unavailable b Metric tons

crop grows at elevations from 800 m to 1500 m above mean sea level (amsl), and these areas lie on both the windward and leeward sides of the Western Ghats, which act as a barrier of the monsoon trade winds, thereby determining the spatial distribution of rainfall. The rainfall pattern differs among the cardamom-growing regions located in Kerala, Karnataka, and Tamil Nadu (Nair et al. 1991). The most important factors that have contributed to the increase in cardamom productivity are the cultivation of high-yielding varieties and improved crop management. However, cardamom export from India has plummeted during the same period. In 1985–1986, cardamom export was 3272 t; in 1989–1990, it hit rock bottom at 173 t—a steep decrease to 5.3% of the 1989–1990 level. In one decade, from 1985–1986 to 1994–1995, export earnings came down from Indian rupees (Rs) 53.46 crores to just Rs 7.6 crores—that is, from US$11.9  million to US$1.8  million—a dramatic decrease of 85%.

1.2.1  Cardamom Cultivation in Other Parts of the World The cultivation of cardamom is getting to be popular in certain parts of PNG. Cardamom grows there in virgin forestlands, and its cultivation is exclusively with private estate owners. The productivity of these estates is very high, with yield levels of 2000–2500 kg ha−1 (Krishna 1997). Total production was about 313 million tons in 1985; by 1993, it had declined to about 54 million tons. Today, PNG production hovers around 68–70 million tons. In Tanzania, the crop was introduced in the beginning of the twentieth century by German immigrants and is being grown in certain parts of the country, such as Amani and East Usambaras (Lawrence 1978).

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1 Introduction

Production was as high as 760  million tons in 1973–1974 but declined to about 127 million tons in 1984–1985, a level that continues to today. Sri Lanka is another small producer of the crop, contributing about 75 million tons to world production annually. India was the leader in world cardamom production until the early 1980s, when Guatemala came into the picture. From thereon, India’s production plummeted while that of Guatemala escalated. By the turn of the last century, whereas India’s production came down by as much as 54% since the beginning of 1970s, that of Guatemala increased by as much as 199%. Guatemala is the major rival to India in cardamom production. A lot of Guatemalan cardamom is smuggled into India through the Nepalese border; this has resulted in a crash in Indian cardamom prices. As of now, nearly 90% of the global cardamom trade is controlled by Guatemala (Table 1.2). Among the many factors that adversely affected India’s cardamom production are the following: 1. Continuous drought, which lasts nearly half the year, combined with indiscriminate deforestation; together, these two factors have led to dramatic changes in the ecology of the cardamom habitat. Deforestation is the major cause of the dwindling of cardamom plantations. 2. Disease and infestation by insect pests. 3. Poor crop management. For example, cardamom nutrition in India is still rooted in “text- book knowledge.” Cardamom is a heavy feeder on potassium, and Indian agronomists and soil scientists have not kept abreast of advancements in crop nutrition. (The relevance of “The Nutrient Buffer Power Concept,” especially with regard to potassium nutrition of cardamom, will be discussed in later sections of this chapter.)

Table 1.2  Cardamom scenario in Guatemala Year 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 Total

Area (ha) 32,336 38,333 41,418 42,656 43,000 43,000 43,000 43,000 47,472 45,133 47,472 47,472 119,540 11,576.70

Production (mt) 7348.32 8845.20 10,591.56 10,432.80 11,340.00 11,340.00 12,201.84 12,474.00 12,927.60 14,969.80 15,603.84 16,329.60 16,692.48

Productivity (kg ha−1) 90.89 92.33 102.29 97.83 105.49 105.49 113.51 116.04 114.57 126.13 131.48 137.59 139.64

Export (mt) 6173.50 7978.82 11,489.69 11,303.71 11,076.91 11,113.20 13,163.47 13,240.58 14,442.62 13,213.37 13,920.98 21,255.70 14,020.78 12,491.79

References

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4. Despite the aforesaid limiting factors, cardamom production in India has increased through enhanced productivity arising from the evolution of high-­ yielding clones, somewhat better crop management, and increased awareness of the importance of phytosanitary measures, especially control of diseases and pests. Between 1988–1989 and 1989–1990, cardamom export from India was 787 and 180 million tons, respectively. Exports crossed the 500 million ton mark in 1991–1992 (544 million tons precisely) and touched the 550 million ton mark in 1999–2000. The unit price of cardamom increased from about Rs 125 (US$3 kg−1) in 1987–1988 to about Rs 395 (US$9) in 1992–1993. In 1996–1997, the unit price was about Rs 384 (US$8.9). The current unit price hovers around Rs 450 kg−1, which is equivalent to about US$10.5. The edge that Guatemala has over India is a lower cost of production. This is the reason Guatemala edges out India in world cardamom trade. India has an extensive domestic market for cardamom. Annual consumption is around 7000 million tons, and a survey indicates that it could be as high as 7300 million tons. The total value of this market is close to Rs 2200 million, which is more than US$50 million. This is, indeed, a large internal market. In addition, apart from individual and household consumption, cardamom in India has an extensive industrial consumptive base. Cardamom-­flavored biscuits, tea, and milk are some end uses for cardamom in the culinary sector, and the spice is used in medicines of herbal origin, in food mixes, and in the ubiquitous “pan masala” (the pervasive Indian “chewing gum,” which leaves a pleasant flavor in the mouth). The industrial consumption of cardamom in India currently is estimated to be about 2050–2010 million tons annually. The demand in the hotel, bakery, and fast-food sector is about 1250 million tons. In the current century, total demand of cardamom in India will escalate to about 9500 million tons annually (George and John 1998).

References George CK, John K (1998) Future of cardamom industry in India. Spice India 11(4):0–24 Krishna KVS (1997) Cardamom plantations in Papua new Guinea. Spice India 10(7):23–24 Lawrence BM (1978) Major tropical spices: Cardamom (Elettaria cardamom). Essent Oil:105–155 Mahindru SN (1982) Spices in Indian life. Sultanchand & Sons, New Delhi Mollison JW (1900) Cardamom cultivation in the Bombay Presidency. Agric. Ledger 11 (quoted by Ridley, 1912) Nair CK, Natarajan P, Jayakumar M, Naidu R (1991) Rainfall analysis of the cardamom tract. J Plant Crops 18(Suppl):184–189 Parry JW (1969) Spices, vol II. Chemical Pub. Co., New York Ridley HN (1912) Spices. McMillan & Co. Ltd., London Van Linschoten JH (1596) Voyage of John huygen Van Linschoten in India, vol II, pp  86–88. (quoted by Watt, 1872) Watt G (1872) Dictionary of economic products of India, vol 3, pp 227–236

Chapter 2

Cardamom Botany

Abstract  The chapter discusses, at length, the taxonomy of cardamom, types, varieties, etc. It further discusses growth, flowering, and fruit set. Additionally, it discusses palynology and pollination biology, including physiology of cardamom and effect of growth regulators. Keywords  Variety · Type · Genetic variability · Hybridization · Biotechnology of cardamom

Cardamom belongs to the genus Elettaria and species cardamomum (Maton). The name is derived from the root Elettari, which, in the popular South Indian language Tamil, means “granules of leaf.” The genus consists of about seven species (Mabberley 1987). Only Elettaria cardamomum (Maton) grows in India—a fact that is of economic importance. Closely related to E. cardamomum (Maton) is E. ensal (Gaertn) Abeywick. E. major (Thaiw.), a much larger and sturdier plant, is a native of Sri Lanka, where it is known as the Sri Lankan “wild” cardamom; its flavor and taste are inferior to those of the Indian variety. E. longituba (Ridl.) Holtt., a large perennial herb whose flowering panicles often grow as tall as 3 m or more, is the Malaysian variety (Holttum 1950), whereas the native Indian variety is a low-­ grown one. The flowers of E. longituba (Ridl.) Holtt. appear singly, and the fruit is large and is not used. Seven species have been identified from Borneo (Indonesia) and have been listed by Sakai and Nagamasu (2000). The related genera are Elettariopsis and Cypbostigma, both of which occur in the Malaysia– Indonesia region.

© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2020 K. P. Nair, The Geography of Cardamom (Elettaria cardamomum M.), https://doi.org/10.1007/978-3-030-54474-4_2

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2.1  Taxonomy Cardamom belongs to the monocot family Zingiberaceae (ginger family) of the natural order Scitamineae. Genus Elettaria consists of seven species, distributed over India, Sri Lanka, Malaysia, and Indonesia. Among these species, only E. cardamomum is economically important (Holttum 1950; Mabberley 1987; Willis 1967).

2.1.1  Type Species: Elettaria cardamomum (Linn.), Maton 2.1.1.1  Etymology The generic epithet Elettaria is derived from Rheed’s Elettari. Elanthari (the modern transcription of Rheed’s name) is still used for the seeds of E. cardamomum. (Thari means “granules” in the local language.) Following is the description of Elettaria provided by Holttum (1950): Stout or fairly stout rhizome, short intervals between leaf-shoots. Leaf shoots are tall with many blade-bearing leaves, while petioles are short and inflorescences arise from rhizome close to the base of a leaf-shoot. They are long, slender, prostrate, either just at the surface of the ground or just below it (not bearing roots), protected by alternate fairly large-scale leaves, in the axils of which cicinni arise, their attachment being sometimes supra-axillary. Cincinni short, bearing a close succession of tubular bracts, each of which encloses entirely the next flower and also the next bract; the flowers in two close rows on one side of the composite axis of the shoot, all pointing in the same direction, curved and opening in succession. Calyx tubular, split about one-fourth of its length down one side, shortly threetoothed; in some species joined at the base to the corolla-tube about as long as calyx; lobes not very broad, subequal, the upper one with a concave apex. Labellum as in Amomum, with yellow median band and red stripes, sometimes so curved that it stands as a hood over the top of the flower. Staminodes none, or short and narrow. Filament of anther very short, broad. Anther longer than filament, stigma small, in close contact with the distal end of the pollen sac. Fruit globose or ellipsoid, thin- walled, smooth, or with longitudinal ridges when ripe. Following is the description provided by Burtt and Smith (1983) for E. cardamomum: Leafy shoot nearly 4 m high, petioles 2.5 cm, lamina about 1 m × 15 cm, lanceo-late, acuminate, lightly pubescent or glabrous below; ligule about 1 cm long, entire. Inflorescence normally borne separately on a prostrate, erect or semierect stalk up to 40 cm long, or more in certain cases. Bracts two to three, 0.8–1.0 cm long, lanceolate, acute glabrous, rather persistent which becomes fimbriate with age. Cincinni many flowered. Bractioles about 2.5 cm long, tubular, mucronate, glabrous. Calyx about 2 cm long, 2- or obscurely 3-lobed, lobes mucronate. Corolla tube as long as calyx. Lobes 1–1.5 cm long, rounded at the apex, the dorsal tube widens. Labellum white, streaked violet, 1.5–2.1 cm at the widest part, ovate, obscurely 3-lobed, narrowed at the base. Lateral staminodes inconspicuous, subulate. Anther sessile, about 1 cm long, parallel, connective prolonged into a short, entire crest. Ovary 2–3 mm long, glabrous. Fruit is a capsule, oblong or more or less globose. The genus has only few species—the most important being E. cardamomum and E. major (E. ensal) from South India and Sri Lanka, respectively.

2.1 Taxonomy

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E. longituba Holttum (Syn. E. longituba) is one of the largest species of the genus grown in Malaysia. Its flowers appear singly at long intervals, and each cincinnus contains only a few flowers. It appears that the cincinnus stops flowering as soon as fruit is formed. The fruits are large, but have no commercial value (Holttum 1950). In their studies on Bornean Zingiberaceae, Sakai and Nagamasu (2000) described five species of Elettaria: E. kapitensis, E. surculosa, E. linearicrista, E. longipilosa, and E. brachycalyx.

2.1.2  Varieties Based on the nature of their panicles, three varieties of cardamom are recognized (Sastri 1952; Table 2.1). The variety Malabar is characterized by a prostrate panicle, and the variety Mysore possesses an erect panicle. The third variety, Vazhukka, is considered a natural hybrid between the two, and its panicle is semi-erect or flexuous. 2.1.2.1  Variety Malabar Plants are medium sized and attain a height of 2–3 m on maturity. The dorsal side of leaves may be pubescent or glabrous. Panicles are prostrate, and the fruits are globose (oblong shaped). This variety grows best at elevations of 600–1200 m amsl. It is less susceptible to an infestation of Thrips, a common cardamom pest. Malabar can thrive under conditions of low rainfall. Table 2.1  Varietal description Features Adaptability Tolerance to drought Plant stature Leaf Panicle Bearing nature Capsule color

Malabar Low elevation (600– 1000 m amsl) Withstands long dry spell (4–6 months) Dwarf (2–3 m) Short petiol Prostrate Early, short span of flowering Pale, golden yellow

Source: Sudarsan et al. (1991) Note: amsl, above mean sea level

Mysore High elevation (900–1200 m amsl) Needs well-distributed rainfall Tall (3–5 m) Long petiole Erect Late, long span of flowering Green

Vazhukka High elevation (900–1200 m amsl) Needs well-distributed rainfall Tall (3–5 m) Long petiole Semi-erect Late, long span of flowering Green

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2.1.2.2  Variety Mysore Plants are robust and grow up to 3–4 m in height. Leaves are lanceolate or oblong– lanceolate, glabrous on both sides. Panicles are erect and the capsules are ovoid, bold, and dark green in color. The capsules variety is better adapted to altitudes ranging from 900 to 1200 m amsl and thrives well under an assured, well-­distributed rainfall pattern. 2.1.2.3  Variety Vazhukka This is a natural hybrid between variety Malabar and variety Mysore and exhibits characteristics that are intermediate between both of these varieties. Plants are robust, like those of variety Mysore. Leaves are deep green, oblong–lanceolate or ovate; panicles are semi-erect (flexous) in nature; and capsules are bold, globose, or ovoid in shape. Two more varieties—variety Mysorensis and variety Laxiflora—have recognizable morphological characteristics. 2.1.2.4  Variety Mysorensis A robust, tall plant that possesses either glabrous or pubescent leaves. This variety has flexous panicles. The flowers are produced in short racemes. The capsules are bold and distinctly three angled. 2.1.2.5  Variety Laxiflora Comparatively less robust than, nor as tall as, variety Mysorensis. Leaves are glabrous with short petioles. This variety has flexuous, lax decumbent panicles. The flowers are produced in 4–40 short lax racemes. The capsules are variable, oblong– oblong fusiform. In India, a number of other cultivars of cardamom are also recognized. In general, they can be considered as ecotypes of var. Mysore, var. Malabar, or var. Vazhukka. Most common among them are Bijapur, Kannielam, Makaraelam, Munjarabad, Nadan, and Thara. 2.1.2.6  The Sri Lankan Wild Cardamom (E. ensal Abheywickrama) The botanical identity of both the Sri Lankan wild cardamom and the Indian varieties just described is shrouded in much confusion. Cardamom varieties have been named differently by various authors as follows:

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13

E. cardamomum var. minus E. cardamomum var. miniscula E. cardamomum var. major E. cardamomum var. majus E. cardamomum var. minor Ridley (1912), who set forth one of the earliest descriptions of cardamom, gives the following details: “There are two forms of varieties of the plant, viz., var. minus with narrower and less firm leaves and globose fruits from 0.5–0.1 in. long, grayish yellow or buff in color. This is confined to South India. Var. majus with shorter stems, broader leaves and oblong fruit, 1- to 2-in. long and rather narrower than the Malabar fruit, distinctly three sided, often arched and dark grayish brown when dry, the seeds larger and more numerous and less aromatic. This is the Ceylon cardamom and is peculiar to that country.” In his notes on cardamom cultivation in Ceylon, Owen (1901) mentions three varieties, which he calls the indigenous Ceylon, the Malabar, and the Mysore. The first two can easily be recognized by the color of the stem. The Malabar plant is green or whitish at the base of the leafy or aerial stem, while the base of the Ceylon plant has a pink tinge. Owen also mentions that the Mysore form is robust, that its panicles are borne perpendicularly from the bulbs, and that the fruits grow in clusters of five to seven. This form does well at high altitudes. E. cardamomum var. major was described earlier as E. major Sm. (Rees Cyclop., 39, 1819), but this name did not find favor with cardamom workers. Many subsequent authors used the terminology indiscriminately and even began mentioning var. Mysore as var. major. While studying the flora of Sri Lanka (Ceylon then), Abheywickrama (1959) coined the name E. ensal for the Ceylon wild cardamom (from Zingiber ensal, under which the plant was described by Gaertner (1791). But Burtt (1980) is of the opinion that the differences are not reasons enough to differentiate this variety into a new species. However, Bernhard et al. (1971) and Rajapakse (1979) provided chemical evidence substantiating the distinct nature of Sri Lankan wild cardamom (Photos 2.1 and 2.2).

2.1.3  Fruit and Seed The cardamom fruit has great commercial value. The fruit is a capsule developed from an inferior ovary. It is more or less three sided with rounded edges. The shape and size vary. In var. Malabar, the fruits are short and broadly ovoid, and dried fruits are somewhat longitudinally wrinkled. In var. Mysore, the fruits are ovoid to narrowly ellipsoid or elongate, and the surface is more or less smooth. The wild Sri Lankan cardamom is much larger, elongate, angular, and distinctly three sided. The dry pericarp is about 0.5 to 1 mm thick, with a rough, woody texture. The capsule has three locules, the septa is membranous, and the placentation is axile. There are five to eight seeds in each locule, and they adhere together to form a mass. The

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Photo 2.1  Popular cardamom variety “Vijetha” Photo 2.2  Single bunch of cardamom variety “Kodku Suvasini”

transverse section of a pericarp shows an outer and an inner epidermis consisting of small polygonal cells and a mesocarp of thin-walled, closely packed, parenchymatous cells. Vascular bundles traverse the mesocarp; each bundle consists of a few xylem vessels, phloem, and a sclerenchymatous sheath partially surrounding the vascular elements. Many resin canal cells (oil cells) are found distributed in the

2.1 Taxonomy

15

mesocarp. The xylem vessels have spiral thickening. Some of the cells contain prismatic needle-shaped calcium oxalate crystals. Externally, cardamom seed has an aril composed of a few layers of thin-walled, elongated cells. In fully mature seeds, these cells contain small oil globules. The testa consists of an epidermis composed of elongated fusiform cells, about 250–1000  μ long, that, in sectional view, are nearly square and about 18 μ wide and 25 μ high (Wallis 1967). A layer of small, flattened parenchyma cells is found below the epidermis. Below the parenchyma cells is a layer of large rectangular cells, about 18–120 μ long and 20–45 μ wide and high, that are filled with globules of volatile oil. Interior to this layer of large cells are two or three layers of small parenchymatous cells. All these layers of cells together form the outer seed coat. The layers get widened around the raphe, where the vascular strand is surrounded by large oil cells. The inner seed coat comprises two layers, with the inner layer consisting of heavily thickened polygonal cells about 15–25 μ in length and breadth and 30 μ high (Wallis 1967). These cells are so thickened that only a small lumen is found at the upper end in which there is a globule of silica that nearly fills the cavity. The inner layer of the inner seed coat consists of a narrow band of thin-walled cells (Wallis 1967). The kernel consists mostly of a perisperm and a small endosperm. The perisperm consists of thin-walled parenchymatous cells that measure about 40–100 μm, each filled with cardamom grains. One or two prismatic calcium oxalate crystals occur in each cell. The endosperm consists of thin-walled, closely packed, parenchymatous cells, 20–40 μm in length, that contain pale yellow-colored deposits. On iodine staining, the contents turn deep blue, showing the presence of starch, and these deposits turn red with Millon’s reagent, indicating the presence of proteins. The endosperm surrounds a small, almost cylindrical embryo, which is made up of thin-walled cells. Parry (1969) and Trease and Evans (1983) provide brief descriptions of the histology of cardamom seeds.

2.1.4  The Cardamom Powder When cardamom seeds are powdered, a grayish-colored powder with darker brown specks, which is gritty in texture and pleasant in smell and flavor, is obtained. The diagnostic character of cardamom powder is given by Jackson and Snowdon (1990): 1. With abundant starch grains filling the cells of the periplasm, the individual starch grains are very small and angular, and a hilum is not visible. 2. The sclerenchymatous layer of the testa is composed of a single layer of thick-­ walled cells that are dark reddish brown in a mature seed; each cell contains a module of silica. 3. Abundant fragments of the epidermis of the testa are composed of layers of yellowish-brown parenchymatous cells with moderately thickened pitted walls.

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4. The oil cells of the testa consist of a single layer of large polygonal rectangular cells with slightly thickened walls and containing globules of volatile oil. This layer is found associated with the epidermis and hypodermis. 5. The parenchyma of the testa is composed of several layers of small cells that are polygonal in surface view, with dark-brown contents and slightly thickened, heavily pitted walls. 6. The abundant parenchyma of the perisperm and endosperm are composed of closely packed, thin-walled cells. 7. The fragment of the arillus is composed of thin-walled cells, elongated and irregularly fusiform in surface view. 8. Calcium oxalate crystals, prismatic in shape, are found scattered in the cells of the perisperm and other cells. 9. Infrequently, groups of xylem vessels with spiral thickening are visible; the thickening is associated with thin-walled parenchyma. The type of cardamom can be determined by counting the number of heavily thickened sclerenchymatous cells per square millimeter of a layer and using a standard figure for each type as follows: Mysore: 3310 Alleppey Green: 3790 Malabar: 4600 The aforementioned classification was given by Wallis (1967). The Sri Lankan wild cardamom contains 3020 sclerenchymatous cells per millimeter of layer.

2.1.5  Growth, Flowering, and Fruit Set in Cardamom As time passes, tillers emerge from the axils of underground stems and vegetative buds emerge from the bases of the stems throughout the year. However, most of the vegetative buds are produced between January and March. The linear growth of tillers increases with the onset of the southwest monsoon—the principal rainfall—in India, and once the rains cease, growth slows down. The linear growth pattern of tillers is similar in all cultivars. It takes almost 10 months for a vegetative bud to develop and about a year to the emergence of panicles from newly formed tillers (Sudarshan et al. 1988). An around-the-year study of the phenology of tiller and panicle production in three varieties of cardamom was carried out by Kuruvilla et  al. (1992). Panicles emerge from the swollen bases of tillers. Generally, two to three panicles emerge from the base of a tiller. Detailed investigations of panicle production and growth and the duration of flowering have been carried out by Pattanshetty and Prasad (1976) and Parameswar (1973). Vegetative shoots acquire maturity in about 10–12 months, when they can produce reproductive buds, and the newly emerging panicles take a period of 7–8 months to complete their growth. With the onset of the monsoon, flowering in cardamom commences. The flowering pattern depends on the region’s agroclimatic characteristics and the cultivars in question. Flowers appear on the panicles after

2.1 Taxonomy

17

4 months, and flowering continues during the next 6 months. The panicles grow either erect (var. Mysore), prostrate, and parallel to the ground (var. Malabar) or in a semierect (flexous) manner (var. Vazhukka). Each inflorescence (panicle) possesses a long cane-like peduncle having nodes and internodes. Each node has a scale leaf in the axil from which flowers are borne on a modified helicoids cyme (cincinnus). Thus, the panicle is branched. Multiple branching of panicles occurs in certain cultivars. In such cases, the central peduncle branches further into secondary and tertiary branches, producing multibranched panicles. Branching can be present at the lower part of the main peduncle, at the top part alone, or throughout the peduncle. The panicles bear leafy bracts on nodes, and flowers are produced in clusters (cincinnus) in the axils of bracts. Earlier researchers on cardamom described the cluster of flowers as raceme, which is incorrect. Each cluster is a cincinnus (Holttum 1950)—that is, a modified helicoid cyme. It takes approximately 90–110 days for the first flower to emerge in a fresh panicle, irrespective of the variety of plant. The cincinni and capsules are formed during their fourth and fifth months, respectively, after the initiation of the panicle (Kuruvilla et  al. 1992). Capsule formation increases until August (Table  2.2) and thereafter declines slowly. The flowers have the typical morphology of zingiberaceous flowers. Flower opening commences from 3.30  A.M. and continues until 7.30  A.M.  Between 7.30 and 8.30  A.M., anther dehiscence takes place. Flowers invariably wither in a day. Normally, flowering is seen round the year on panicles produced during the same year, as well as on panicles produced in the previous year. Flowering is spread over a period of 6 months, from May to October, in India, when the majority of cardamom plantations still are in the southwest monsoon period. Almost 75% of the flowers are produced during June–August. The time required to reach the full-bloom stage from the flower bud initiation stage ranges from 25 to 35  days, and capsules mature in about 120  days from the full-bloom stage (Krishnamurthy et al. 1989a). Table 2.2  Development and pattern of growth of panicles Month January February March April May June July August September October November December

Malabar A 3.76 6.34 7.91 11.85 17.52 18.80 18.40 17.63 18.40 18.52 18.41 18.90

B – – – – 13.63 14.93 15.40 15.93 13.76 14.71 14.43 14.44

C – – – – – 18.56 34.30 39.23 31.23 3.81 1.52 0.33

Vazhukka A B 6.77 – 9.20 – 12.50 – 13.02 – 22.76 11.06 23.73 14.70 22.13 15.73 18.86 11.36 16.46 9.83 25.07 14.40 25.20 14.40 25.87 14.20

C – – – – – 4.20 8.16 8.13 3.96 2.60 0.67 0

Mysore A 4.83 7.23 11.0 16.60 23.50 23.66 21.30 23.66 24.36 24.96 25.11 25.44

Source: Kuruvilla et al. (1992) Note: A, panicle length (cm); B, number of cincinni; and C, number of capsules

B – – – – 14.93 17.13 16.13 16.76 16.63 16.15 16.07 16.07

C – – – – – 14.06 21.86 29.70 19.93 11.15 3.74 0.48

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2.1.6  Palynology and Pollination Biology The pollen grains of cardamom plants are rich in starch and, while shedding, are two celled. Moniliform refractive bodies can be seen in some pollen grains. The exine develops warty projections that are spinescent (Panchaksharappa 1966). Pollen fertility is maximum at the full-bloom stage and low at the commencement and cessation of flowering periods (Parameshwar and Venugopal 1974). Pollen grain size varies from 75 to 120 μ in different varieties, and the grains lose their viability quickly. After 2 h, only 6.5% are viable, and, after 6 h of storage, none (Krishnamurthy et  al. 1989a). During early and later stages of flowering, pollen fertility tends to decline. The grains germinate in a 10% sucrose solution, and the addition of 200 ppm boric acid enhances germination and tube growth (Parameshwar and Venugopal 1974). Kuruvilla et al. (1992) found that 15% sucrose and 150 ppm boric acid favored pollen germination and tube growth at an ideal temperature of 15–20 °C; 5–10 ppm of coconut water, GA, cycocel, and ethrel enhanced pollen germination and tube growth significantly. Cardamom plants have bisexual flowers. The pollen and stigma are so placed within the flower that, without external intervention, pollination cannot take place. Honeybees (Apis cerana, Apis indica, and Apis dorsata) visit cardamom plantations during the flowering stage to collect nectar and pollen, and they achieve over 90% pollination. The stigma remains receptive from 4 A.M. on the day of flowering, and the receptivity is maximum between 8  A.M. and 12  P.M. (Krishnamurthy et  al. 1989a; Kuruvilla and Madhusoodanan 1988). Peak pollen activity occurs around noon (Belavadi et al. 1998; Parvathi et al. 1993) and coincides with peak pollination. A detailed study of pollination in cardamom in PNG has been carried out by Stone and Willmer (1989). There, the most common foragers are Apis mellifera and, to some extent, Apis sapiens. Over time, Apis mellifera was seen to show changes in pollen-foraging activity. Foraging commences around 7 A.M. and peaks at around 10 A.M. By 12.30 P.M., pollen activity declines substantially, and by that time, the majority of stigmas get pollinated. Interesting observations on flower structure and pollination by honeybees have been made by Belavadi et al. (1997). In cardamom flowers, nectar is present in the corolla tube, which is 23 × 2.08 mm long (a 21.48- to 30.4-mm range) and through which the style passes. The honeybees (Apis cerana and Apis dorsata) drew nectar up to 11.45 × 2.65 and 11.65 × 1.85 mm, respectively, despite their short tongue lengths (14.5 and 5.5  mm, respectively). Controlled experiments using capillary tubes of similar dimensions showed that the depth of feeding by the two bee species corresponded to their tongue length when there was no style. When a style was introduced, the depth of feeding increased with increase in style thickness. The presence of a style inside the corolla tube helped bees to draw more nectar from the cardamom flowers. The mean number of flowers per bush that open per day is 34.5. The mean proportion of flowers per bush visited by each Apis mellifera and is 25%, independent of the number of flowers present on a plant and independent of the time of the day. Hence, the mean number of flowers visited is only 8.6. Pollen production

2.1 Taxonomy

19

per flower is reported to be 1.3—0.2  mg, and this quantity gets diminished to 0.6—0.2 mg after the visit of a bee, indicating that during the first foraging about 50% of the pollen is removed. Cardamom nectar contains 55–100 mmol liter−1 of glucose and is neutral in reaction. The amino acid concentration at 8  A.M. is 3 mM. Over time, nectar volume varies greatly. The initial volume at dawn is about 1.6 μl and by 11 A.M.; this increases to about 209 μl. The increase is due to the active secretion by the nectaries at the base of the corolla tube. Nectar volume drops rapidly following foraging by a bee (Stone and Willmer 1989). In one location in PNG, the number of visits per day by Apis mellifera to each flower was 31; in another location, visits per day averaged only 10.3. In the former area, fruit set was much higher. Bee-pollinated fruits were found to contain 11 seeds per capsule, on average (Chandran et al. 1983), in South India, whereas they contained 13.8 seeds per capsule, on average, in PNG. Belavadi et al. (1993, 1997, 1998), Parvathi et al. (1993), and Belavadi and Parvathi (1998) have carried out detailed studies on pollination ecology and biology of cardamom in a cardamom-cropping system in Karnataka in South India. The pollination activity there starts around 7.30 A.M. and continues until 6.30 P.M., peaking between 11 A.M. and 1 P.M. The bees appear on cardamom clumps when the temperature is around 21  °C.  Individual foragers of Avis cerana made four to seven trips to a single patch of flowers in a day, and the number of flowers visited on each successive trip progressively increased. In a day, individual foragers visited 157–514 flowers. A flower is visited as many as 120 times on a clear, sunny day; 57 times on a cloudy, rainy day; and, on average, 20 times a day. The mean number of flowers visited by a bee at a given clump is 12.32 when mean number of flowers per clump is 30. The number of honeybee colonies required for effective pollination in cardamom has also been calculated by the aforesaid workers. For 3000 plants per hectare planted 1.8 m apart, there will be approximately 60,000 flowers per day ready for effective pollination. On the basis of the pollinator activity, a minimum of three colonies per hectare are needed, assuming that a colony will have about 5000 foragers. An isolation distance of 15 m for seed production has been suggested for seed production (Belavadi et al. 1993).

2.1.7  Fruit Setting When ripe, cardamom fruit is globose or ellipsoid, thin-walled, and smooth or with longitudinal ridges. Fruit shapes indicate varietal variations. The fruit is green colored and turns golden yellow on ripening. The seeds are white when unripe, turn brown on aging, and become black on maturity; their numbers per capsule vary between 10 and 20, depending on genotypes. A thin mucilaginous membrane (aril) covers the seeds. The extent of fruit set is highest when the atmospheric humidity is very high in the cardamom region; fruit set is scanty in summer months, even when the crop is irrigated. This difference clearly indicates that the crop thrives best in a cool, overcast climate. In general, the percentage of fruit set is high among young plants, and when plants overshoot the economic life span of the spice, fruit set declines to 50% or even less.

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2.1.8  Physiology of Cardamom 2.1.8.1  Photosynthesis Among the growth parameters, total leaf area (TLA) is closely associated with photosynthesis and the production of dry matter. Hence, a precise estimation of TLA and canopy density is important in estimating productivity. Korikanthimath and Rao (1993) reported a reliable method for TLA estimation based on linear measurements of intact leaves followed by appropriate regression analysis. There were varietal differences in the TLA factor. The fraction of light that the leaves absorb has a direct bearing on crop growth and canopy development. Laboratory studies on photosynthetic efficiency in cardamom (cvs. PV-19 and PR-107) indicated that efficiency was greater at low light intensities than at higher ones. A low light compensation point favors photosynthesis. Translocation pattern showed that the rhizome was the major sink, followed by the panicle and roots. Unlabeled leaves did not receive much of the labeled photosynthates from labeled leaves (Vasanthakumar et al. 1989). Kulandaivelu and Ravindran (1982) studied the photosynthetic activity of three cardamom genotypes, measured at the rate of oxygen liberated by isolated chloroplasts. Results showed a drastic reduction in photosynthetic rates in plants exposed to warm climate. As much as a 60–80% decrease in the level of total chlorophyll was noticed in all three varieties tested. The light requirement for a cardamom nursery is approximately 50% of normal (Ranjithakumari et al. 1993), and the growth and production of tillers is best at this light intensity. 2.1.8.2  Effect of Growth Regulators on Cardamom Fruit Setting In cardamom, a high percentage of flowers is shed before they reach maturity; nearly 80% of the fruit drops (Parameshwar and Venugopal 1974). Temperature, wind, humidity, nutritional deficiencies, physical injuries, competition for resources, soil fertility, pests and diseases, and so on affect fruit set and fruit drop (Kuttappa 1969). In cardamom, growth regulators are important for proper fruit set. Table  2.3 gives the effect of NAA, GA, and 2,4–8 on fruit set and fruit weight (Krishnamurthy et al. 1989b). Significant differences are noticeable in the case of fruit set. Tissue concentration of auxins was highest 36 h after pollination at 315 mg g−1 of tissue and declined further, to 80 mg g−1, 30 days after pollination. The fall in auxin activity resulted in the formation of an abscission zone, producing shedding of immature capsules. The application of 40 ppm NAA or 4 ppm of 2,4–8 decreased the capsule drop and led to an increase in yield (Vasanthakumar and Mohanakumaran 1998). Gibberellic acid (GA) at 25, 50, 100, 150, 200, 250, and 300  ppm and 2,4–8 at 2–5  ppm and 10  ppm were sprayed on cardamom plants, and the response was monitored. The plants showed increased panicle length, especially with GA at 50  ppm, and the maximum fruit set was observed at 200  ppm spray (Pillai and

2.1 Taxonomy

21

Table 2.3  Growth regulators and fruit set Treatment Control NAA

GA

2,4-D

LSD (p = 0.05) LSD (p = 0.01)

25 ppm 50 ppm 75 ppm 25 ppm 50 ppm 75 ppm 2.5 ppm 5.0 ppm 7.5 ppm

Mean fruit set (%) 43.20 60.75 61.62 67.04 37.72 48.73 54.11 69.80 65.12 47.56 10.69 14.18

Fruit weight (g) 0.80 0.85 0.83 0.71 0.78 0.83 0.90 0.80 0.79 0.82 N.S. –

Source: Krishnamurthy et al. (1989b) Note: LSD least significant difference, N.S. not significant

Santha Kumari 1965). Indoleacetic acid (IAA) and indolebutyric acid (IBA) failed to enhance fruit set (Nair and Vijayan 1973). Siddagangaih et al. (1993) investigated the effect of chloromequat, daminozide, ethephon, and malic hydrazide (250 ppm). Daminozide (1500 ppm), chlormequat (250 ppm), and ethephon (100 ppm) significantly enhanced tiller production and other vegetative characters when applied on 7-month-old seedlings but had little effect on other morphological characters. 2.1.8.3  Effect of Moisture Stress on Cardamom Yield In South India, the states of Kerala and Karnataka experience drought for about 4–5  months a year. Large-scale yield losses are observed due to drought in the Idukki, Palakkad, and Wayanad districts of Kerala State, where cardamom is extensively grown. Identifying cardamom genotypes that are tolerant to moisture stress is an important prerequisite for enhancing cardamom productivity in India. At the Regional Cardamom Research Station in Mudigere, in Coorg district of Karnataka State, cardamom genotypes were screened to select clones that would be tolerant to drought. Clones differ in their susceptibility to drought. Krishnamurthy et  al. (1989a) investigated the chlorophyll stability index (CSI) of three prominent varieties of cardamom—Malabar, Mysore, and Vazhukka—to see whether it would be a reliable indicator of drought tolerance. For purposes of comparison, related taxa, namely, Hedychium flavescence and Amomum subulatum, were also investigated. Malabar had the highest CSI (43.14), and Mysore had the lowest (24.5); Vazhukka was intermediate (31.14). CSI is expressed as a percentage. Electrolyte leakage was highest (66.65%) in Mysore and was 69.42% in Vazhukka and 43.90% in Malabar. These results clearly indicate an inverse relationship between CSI and electrolyte

22

2  Cardamom Botany

leakage among the varieties, pointing to the important reason that Malabar outperforms both Mysore and Vazhukka varieties. Among the other physiological parameters, dry matter accumulation (DMA) and harvest index (HI) are important in helping breeders in their programs for cardamom improvement. DMA during drought spells over a 3-year period has been investigated by Krishnamurthy et al. (1989a). The authors investigated a number of cardamom clones and found significant variation among them. DMA during the drought period of March–June varied from 161 g per plant to 279.5 g per plant. At the end of the drought spell (June), DMA ranged from 195 g per plant to 391 g per plant. Those clones that had the highest DMA had the maximum leaf area index, another yield-determining physiological parameter. Korikanthimath and Mulge (1998) investigated the various vegetative and physiological parameters in 12 clones planted in the “Trench System,” a specialized pattern of planting in which the trenches measure 1.8 m × 0.6 m. These authors measured the dry matter content of roots, rhizome, panicles, capsules, tillers, and leaves and found that it varied significantly among the clones. Total dry matter varied from 2759 to 4853 g. Dry matter in capsules varied from 13.2 to 234.3 g. The harvest index varied from 0.06 (for the native variety) to 0.091 (for a “selection” clone). The partitioning of photosynthates within the plant is governed by genetic variability. This relationship is reflected in the DMA in capsules. These investigations help the breeders to target high productivity in cardamom.

2.2  Crop Improvement Crop productivity can be enhanced in cardamom by, first, the use of high-yielding genetic materials and, second, improved crop and soil management practices. The major constraints on cardamom productivity are the lack of genotypes that produce a superior yield and the onslaught of drought and devastation by insect pests and diseases. As far as the first factor is concerned, germplasms with a high-yield potential, superior capsule quality, and wide adaptability are the three criteria affecting productivity. The selection of clones that possess resistance or tolerance to major pests and diseases, as well as to drought, should be the top priority for a crop-­ breeding program.

2.2.1  Germplasm Because cardamom is a cross-pollinated crop that is propagated mostly by seeds, the plant’s natural variability is fairly high. Assembling a wide range of genetic stock, which forms the basis for further breeding or selection work, is the first step in molding new varieties for use by farmers and end users. Hence, the collection, conservation, evaluation, and exploitation of existing germplasm deserve the utmost

2.2  Crop Improvement

23

Table 2.4  Spread of cardamom germplasms in India

Center Regional Research Station of the Indian Institute of Spices Research (IISR), Appangala, Coorg district, Karnataka State, India, under the administrative control of the Indian Council of Agricultural Research, New Delhi, India Indian Cardamom Research Institute, Myladumpara, Idukki district, Kerala State, India, under the administrative control of the Ministry of Commerce, Government of India Cardamom Research Center, Pampadumpara, Idukki district, under the administrative control of the Kerala Agricultural University, Thrissur, Kerala State, India Regional Research Station, Mudigere, Chickmagalur district, Karnataka State

Germplasm under cultivation 314

Wild and related taxa 13

600

12

72

15

236

7

importance in breeding strategies. In the 1950s, in India, two surveys were conducted in cardamom-growing regions: One sought to record genetic resources and wild populations (Mayne 1951) and the other to understand the geographical distribution and environmental impact on cardamom (Abraham and Thulasidas 1958). These were the first organized attempts in India to catalog the cardamom crop. Thereafter, explorations for germplasm collection were carried out by six research organizations in the country, and the total number of accessions presently available at different research centers is 1350 (Madhusoodanan et al. 1998, 1999; Table 2.4). Earlier documentation was based on an old descriptor (Dandin et al. 1981), and a key for the identification of various types was formulated (Sudarshan et al. 1991). During 1994, a detailed descriptor for cardamom was brought out by the International Plant Genetic Resources Institute, in Rome, Italy. Among the germplasms collected, genotypes having marker characters include terminal panicle, narrow leaves, pink-­ colored tillers, compound panicles, and elongated pedicel. Asexuality, cleistogamy, and female sterility are a few of the variations that have been observed. Conservation of cardamom genetic resources under in situ conditions does not exist, although natural populations occur in protected forest areas, especially the world-famous “Silent Valley Biosphere Reserve” in Kerala State, where a sizeable population of cardamom plants exists in their natural habitat. Many organizations are now undertaking ex situ conservation of cardamom. Table 2.4 details holdings in these centers.

2.2.2  Genetic Variability in Cardamom The accessions of cardamom germplasm available at the Regional Research Station, Mudigere, have been classified by Krishnamurthy et al. (1989a). There are 26 distinct types, based on leaf pubescence, height and color of aerial stem, panicle type, and so on. A study to assess the variability among 210 germplasms assembled from

24

2  Cardamom Botany

all major cardamom-growing regions at the Cardamom Research Center, Appangala, was carried out by Padmini et al. (1999). The results of the study indicated that, in general, var. Vazhukka and var. Mysore are more robust than var. Malabar. The total number of tillers, as well as the number of bearing tillers per plant, leafy stem diameter, and the number of leaves are more in var. Vazhukka and var. Mysore than in var. Malabar. The mean number of panicles per plant is higher in var. Malabar than in the other two. Plant characters, such as panicle number, nodes per panicle, internode length, and capsule length, exhibited a high coefficient of variation. Among the Malabar accessions, percentage coefficient variation was highest for the number of panicles per plant. In var. Mysore, the characters having the highest variability were panicle per plant and internode length of panicle. In var. Vazhukka, the highest coefficient of variation was recorded for panicles per plant, followed by the number of bearing tillers per plant. Observations on natural variations in morphological and yield parameters under the cardamom-growing situation in Idukki district of Kerala State were recorded by George et al. (1981). Highest variability was observed with regard to panicle characters (Anon 1958, 1986a, b, c, 1987). George et al. (1981) collected 180 accessions from the wild, as well as from cardamom-growing regions of the Western Ghats of Kerala State. These researchers isolated distinct morphotypes and 12 ecotypes showing heritable adaptations. They observed that var. Mysore and var. Vazhukka attained a height of nearly 6  m and were more vigorous than var. Malabar. One clone had very narrow leaves, 3 cm wide. In two accessions, tillers had characteristic pink and pale-green colors. In general, each tiller had two panicles, and accessions having three or four panicles per tiller were present, especially among the Munzerabad clones. Another clone, known as “Alfred clone,” produced both basal and terminal panicles. Panicle length was highly variable among accessions, ranging from 30 to 200 cm, with the mean being 140 cm in var. Mysore and var. Vazhukka and 80 cm in var. Malabar. Some accessions produced multibranched panicles. The number of flowers or fruits varied from 4 to 36 per cincinnus. Variations were noticed in fruit shape as well. Plants having multibranched panicles or compound panicles occur in small proportions in the segregating populations of certain lines. Padmini et  al. (2000) investigated the variability among different types of compound panicles, which have mostly the var. Vazhukka type of inflorescence. Among the compound panicles, the proximal-branching type is more prevalent than the distal- or entire-branching type. The contribution of such branching toward yield (weight of fresh and dry capsules) varied from 12 to 41%. Branching did not influence other yield or quality characters.

2.2.3  Genetic Upgradation of Cardamom Cardamom can be propagated both sexually and asexually through vegetative cuttings. Techniques such as selection, hybridization, mutation, and polyploid breeding are used as a means of genetic upgradation of the crop. Studies on certain aspects of

2.2  Crop Improvement

25

crop improvement in cardamom have also been carried out in Sri Lanka (Melgode 1938), Tanzania (Rijekbusch and Allen 1971), Guatemala (Rubido 1967), and PNG (Stone and Willmer 1989).

2.2.4  Selection There are definite breeding pathways in cardamom selection, especially with regard to clonal selection. Gopal et al. (1990, 1992) carried out extensive correlation and path analysis, which showed that the dry weight of capsules per plant was positively correlated with other polygenic characters, such as tiller height (r = 0.88), productive tillers per plant (r = 0.78), panicles per plant (r = 0.998), capsules per panicle (r  =  0.998), fresh weight of capsules per plant (r  =  0.99), length of panicles (r = 0.87), nodes per panicle (r = 0.96), and internodal length of panicle (r = 0.63). Number of panicles per plant, fresh weight of capsules per plant, nodes per panicle, and internodal length of the panicle showed statistically significant positive direct effects on yield. Panicles per plant showed the maximum direct effect on yield, followed by fresh weight of capsules per plant. The authors concluded that panicles per plant, fresh weight of capsules per plant, nodes per panicle, and internodal length of panicle were useful characters for the improvement of cardamom yield. Patel et al. (1997, 1998) have suggested the use of traits such as panicles per bearing tiller, panicles per clump, recovery ratio, and capsules per panicle as important criteria in the selection for cardamom yield. In a study using 12 genotypes, these researchers found that yield per clump had a significant positive correlation with capsules per panicle (r = 0.967), cincinni per panicle (r = 0.645), tillers per clump (r = 0.639), panicle length (r = 0.559), panicles per clump (r = 0.537), bearing tillers per clump (r = 0.340), vegetative buds per clump (r = 0.309), and recovery ratio (r = 0.224). A negative correlation was observed between fresh yield per clump and dry capsules per kilogram (r = −0.486). Patel et al. concluded that capsules and cincinni per panicle, bearing tillers and panicles per clump, panicle length, and vegetative buds per clump are the significant attributes that are primarily responsible for high yield of cardamom, so selection for yield improvement should be based on these attributes. A systematic evaluation of germplasm accessions in India during the 1980s resulted in the identification and release of some elite clonal selections (Table 2.5). The initial collection for desirable traits was made from planters’ fields, as well as from wild habitats, on the basis of certain parameters. In order to isolate elite clones, germplasm collections were subjected to initial evaluation trials, followed by comparative yield trials and multilocation tests, in various agroecological situations. Only a few studies were conducted for the selection of seedlings having precocity in bearing, and the results indicate that this phenomenon has no positive bearing on yield (Madhusoodanan and Radhakrishnan 1996). Selection for drought tolerance has also been attempted; initial results indicate that those genotypes that are tolerant to drought are low yielders.

26

2  Cardamom Botany

Table 2.5  Elite selections of cardamom

a

Selection Mudigere-1

Plant type Malabar

Average yield (kg ha−1) 275

Mudigere-2

Malabar

476

PV-1

Malabar

260

CCS-1 (IISR “Suvasini”)

Malabar

409

ICRI-1

Malabar

656

ICRI-2

Mysore

766

ICRI-3

Malabar

599

BRI (IISR “Avinash”) TDK-4

Malabar

960

Malabar

456

PV-2

Malabar

982

IISR “Vijeta” (NKE-12)a Farmer’s Selection “Njallani Green Gold”b

Malabar

643

Vazhukka –

Oil (%) 8

Distinguishing features Compact plant suited for high-density planting. Tolerant to hairy caterpillars and white grubs. Short panicle, oval and bold pale-green capsules, leaves pubescent 8 Round capsule, suited to hilly zones of Karnataka State 6.8 Early maturing variety with slightly ribbed, light-green capsules. Short panicle, close cincinni, elongated capsules 8.7 Early maturing variety suitable for high-density planting. Long panicle, oblong, bold, parrot-green capsules 8.3 Early maturing, profusely flowering variety. Long panicle, globose, extrabold, dark-­ green capsules 9.0 Performs well in irrigated conditions. Suitable for high-altitude planting. Long panicle, oblong, bold, parrot-green capsules 6.6 Early maturing, nonpubescent leaves, oblong, bold, parrot-green capsules 6.7 Selection from hot-spot areas. Resistant to rhizome rot disease 6.4 Suitable for low-rainfall area, highly adapted to lower Pulney hills of Tamil Nadu State 10.45 Selection from OP seedling progeny of PV-1. Early maturing, bold capsules, high dry recovery, tolerant to Thrips 7.9 Suited to highly shaded mosaic disease areas, oblong capsule, virus resistant – Clonal selection by a cardamom grower in Idukki district of Kerala State High-­ yielding, bold capsules, more than 70% of cured cardamom above 7 mm in size

Yield up to 1600 kg ha−1 in farmer’s fields Yield up to 2475 kg ha−1 in farmers’ fields

b

2.2.4.1  Selection for Biotic Stress Tolerance At the Cardamom Research Center, Appangala, Karnataka State, under the administrative control of the Indian Institute of Spices Research, Calicut, Kerala State, a survey was conducted to collect disease escapes from the hot-spot areas of the devastating katte disease of cardamom. Collections of natural katte escape (NKE) lines from such surveys were field evaluated and subjected to artificial inoculation

2.2  Crop Improvement

27

through the use of insect vectors. Then, the plants that did not get infected, even after continued screening, were field evaluated again in a hot-spot area. Some of the selections were found to be good yielders with good quality, comparable to those already released for cultivation. One specific collection, RR-1, gave the highest yield and was found to be resistant to the rhizome rot caused by Phytophthora sp. The yield is comparable to that from NKE lines. Further studies were undertaken, and improvement of the NKE lines was accomplished with the diallel crossing technique (IISR 1997–1998). 2.2.4.2  Selection for Drought Tolerance For drought tolerance studies on cardamom selections, parameters such as relative water content, membrane leakage, stomatal resistance, and specific leaf weight have been used as important criteria among cultivars (IISR 1997–1998). 2.2.4.3  Hybridization The popular cardamom variety Vazhukka may have originated as a natural cross between var. Malabar and var. Mysore. Since cardamom can be propagated by both sexual and vegetative methods, hybridization is a useful tool for crop improvement. Because only one species of cardamom occurs in India, crossing in cardamom is confined to intraspecific levels. On account of its perennial, cross-pollinated, heterozygous nature, the conventional methods for evolving homozygous lines in cardamom are time-consuming. Both intergeneric and intervarietal hybridizations have been carried out by various cardamom researchers. The former method was tried with the objective of transferring disease resistance. Such attempts have not borne encouraging results, except in the case of fruit set in a cross with Alpinia nutans (Parameswar 1977). All other intergeneric crosses involving Amomum, Alpinia, Hedychium, and Aframomum were sterile (Krishnamurthy et al. 1989a; Madhusoodanan et al. 1990). Intervarietal and intercultivar hybridizations have been carried out to produce high-yielding heterotic recombinants. A diallel cross involving six related types having characters of early bearing, bold capsule, high-yield, long panicle, leaf rot resistance, and multiple branching was carried out, and 30 cross combinations were made. All the resulting hybrids were more vigorous than the parental lines (Krishnamurthy et al. 1989a). In another study, intervarietal hybridization was carried out with different varieties of cardamom. This study resulted in cross combinations of 56 F1 hybrids. Evaluation of these hybrids led to the isolation of a few high-yielding heterotic recombinants having an average yield of 470–610  kg ha−1 under moderate management (Madhusoodanan et al. 1998, 1999).

28

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2.2.4.4  Selection Among Polycross Progenies The impact of selection in a polycross progeny population was investigated by Chandrappa et al. (1998). Promising clonal selections of var. Malabar, including the prominent variety Mudigere-1, were grown in isolation, and open-pollinated varieties of these selections were evaluated. In 34% of the progenies, average yield was found to be significantly higher than the average yield of the control variety, Mudigere-1. This increase in yield varied from 1 to 149%, and promising clones were 691, 692, D11, and D19. The researchers found that improvements in cardamom yield could be achieved more effectively through a polycross breeding program. Compared with the highest yield per plant of 1663 g, expected in the progenies of Mudigere-1, one selection from polycross seeds of Mudigere-1 yielded 2360 g per plant, which is 44% higher, and another progeny from the line D 237 gave 2670 g per plant yield, a 60% higher yield. The researchers also found, on the basis of the polycross progeny test, 38% of the clones were poor in combining ability and could be rejected. They further suggested that lines with better combining ability, such as Mudigere-1, C1-691, C1-692, D-11, D-18, D-19, D-186, D-535, and D-730, had 46–149% higher yields compared with the mean yields of the polycross progeny, and the checks could be used to establish a restricted polycross nursery to isolate higher-yielding selections. The authors had investigated a population of more than 3000 plants. 2.2.4.5  Polyploidy Polyploids (2n = 4x = 96) were successfully induced in cardamom by treating the sprouting seeds with 0.5% aqueous solution of colchicines. The polyploid lines exhibited gigantism. Still, an increased layer of epidermal cells, a thicker cuticle, and a higher wax coating on the leaves found in the induced polyploid lines are characters generally associated with drought tolerance in nature. The meiotic behavior of induced polyploids was almost normal, and they had reasonably good fertility. In all yield characters, the tetraploids were reported to be inferior to the diploids (Anon 1986a). 2.2.4.6  Mutation Breeding Attempts to induce desirable mutants by using physical mutagens, namely, X-rays and γ-rays (Co60 source), and chemical mutagens (ethyl methane sulfonate and maleic hydrazide) have been carried out. Of the large number of selfed and open-­ pollinated progenies of M1 plants that did not get infected after repeated cycles of inoculations with katte virus vector, 12 plants were selected as tolerant to the disease (Bavappa 1986). There are reports on sterility (Pillai and Santha Kumari 1965) and the absence of macromutation in M1 generation and its progeny (Anon. 1987). No desirable mutant could so far be developed in cardamom.

2.2  Crop Improvement

29

2.2.4.7  Biotechnology 1. Micropropagation (a) The technique of micropropagation, which eliminates systemic pathogens such as viruses, offers the best hope for rapid vegetative propagation of elite clones or varieties (Table 2.6). Replanting of senile, seedling-raised plantations with selected high-yielding clones multiplied through micropropagation can give a five- to sixfold increase in the current average productivity of cardamom. Micropropagation can be used for the following applications (Bajaj et al. 1988): (i) Increase in the propagation rate of plants (ii) Availability of plants throughout the seasons round the year (iii) Protection against pests and diseases under controlled conditions (iv) Production of uniform clones (v) Production of uniform secondary metabolites In cardamom, different tissue culture approaches have made use of techniques such as (1) callusing, (2) adventitious bud formation, and (3) enhanced axillary branching. The first report of a cardamom tissue culture was published by Rao et al. (1982), who achieved regeneration of plants from callus cultures. Nadgauda et al. (1983) achieved a multiplication ratio of 1:3 when sprouted buds were cultured in MS medium supplemented with BA (0.5 mg liter−1), kinetin (0.5 mg liter−1), IAA (2 mg Table 2.6  Tissue cullture in cardamom Explant Vegetative bud

Media composition MS + 1 mg liter−1 BA, 0.5 mg liter−1 NAA MS + 0.5 mg liter−1 BA, 0.5 mg litercapsules, high dry recovery, tolerant to Thrips1 kinetin, 2 mg liter−1 biotin, 0.2 mg liter−1 calcium pantothenate, 5% coconut milk Rhizome of MS + 1 mg liter−1 2,4–8 0.1 mg TC plants liter−1 NAA, 7 mg liter−1 BA, 0.5 mg liter−1 kinetin Immature MS + 0.5 mg liter−1 NAA 0.5 mg panicles liter−1 kinetin, 1 mg liter−1 BA, 0.1 mg liter−1 calcium pantothenate, 0.1 mg liter−1 folic acid, 10% coconut milk Callus derived MS + 10% coconut milk 2–5 mg liter−1 BA, MS + 1 mg liter−1 2,4-D, from vegetative 0.1 mg liter−1 NAA, 1 mg liter−1 BA, buds 0.5 mg liter−1 kinetin

In vitro response Multiple shoots, in vitro rooting Multiple shoots, in vitro rooting

References Nirmal Babu et al. (1997) Nadgauda et al. (1983)

Callus

Lukose et al. (1993)

Conversion of floral primordium into vegetative buds

Kumar et al. (1985)

Regeneration of plantlets organogenesis and regeneration of plantlets

Rao et al. (1982) and Lukose et al. (1993)

30

2  Cardamom Botany

liter−1), calcium pantothenate (0.1 mg liter−1), biotin (0.1 mg liter−1), and coconut water (5%). The plantlets were successfully rooted and grown in the field. Kumar et  al. (1985) reported direct shoot formation from inflorescence primordium cultured with MS medium containing NAA, kinetin, and BAP. These researchers could get the plantlets rooted. Reghunath and Bajaj (1992) gave a detailed account of micropropagation methods in cardamom. Lukose et  al. (1993) used MS medium containing 20% coconut water, 0.5  mg liter−1 NAA, 0.2  mg liter−1 IBA, 1.0  mg liter−1 6-benzyladenine, and 0.2  mg liter−1 kinetin. The plantlets are rooted in White’s basal medium containing 0.5 mg liter−1 NAA and are hardened in a soil– vermiculture mixture. Other reports include those of Priyadarshan and Zachariah (1986), Vatsya et  al. (1987), Priyadarshan et  al. (1988), Reghunath (1989), Reghunath and Gopalakrishnan (1991), Nirmal Babu et  al. (1997), and Pradip Kumar et al. (1997). Indian biotech companies, such as A.V. Thomas and Co., Ltd., and Indo-American Hybrid Seeds, based mainly in South India, are involved in the commercial multiplication of cardamom. 2. Propagation by Callus Culture Cardamom micropropagation has been discussed in detail by Reghunath and Bajaj (1992), who investigated various explants, such as shoot primordium, inflorescence primordium, immature inflorescence segments, and immature capsules, and tested serial treatments with 95% alcohol, 2–4% sodium hypochlorite, and 0.05–0.2% mercuric chloride for decontamination of explants. Both MS and SH (Schenk–Hildebrandt) media at half and full strengths were tested, along with auxins such as NAA, IAA, and 2,4-D alone and in combination. The cultures on 0.6% agar were incubated at a light intensity of 1000 lux and a 16-h photoperiod. Maximum callus formation was seen in MS medium supplemented with 4 mg liter−1 NAA and 1 mg liter−1 BAP. On subculturing in an auxin-free medium having 3 mg liter−1 BAP and 0.5  mg liter−1 kinetin, this callus started callogenesis, with each culture producing six to nine meristemoids. Subsequently, culturing in the same medium produced shoots within 28  days. Coconut water (15%) enhanced callogenesis. 3. Propagation Through Enhanced Axillary Branching Method Seventeen media formulations using shoot primordial as explants were tested by Priyadarshan et al. (1992), who obtained the best results with MS medium fortified with IAA, BAP, kinetin, calcium pantothenate, biotin, and coconut water. Reghunath and Bajaj (1992) have outlined the method of culturing, which uses shoot and inflorescence primordial explants; the media tested were MS and SH. The SH medium was found to be better than the full- or half-MS medium, since it gave 31% more shoot dry weight. A liquid medium culture under agitation using a gyratory shaker produced 111.5% more axillary branches than explants cultured in semisolid medium. The cultures were maintained at 23 ± 2 °C, a light intensity of 3000 lux, and a 16-h photoperiod. The number of axillary branches was maximum in the medium containing 4 mg liter−1 of BAP and 0.5 mg liter−1 of NAA. Axillary branch

2.2  Crop Improvement

31

production was enhanced by coconut water. Var. Mysore and var. Vazhukka produced more axillary branches than those produced by var. Malabar. The following culture materials were proposed by Nirmal Babu et al. (1997) for micropropagation: Explants: Rhizome bits with vegetative buds Surface sterilization: Washing in running water, followed by washing in detergent solution, followed by washing in 0.1% HgCl2 Incubation: 22 ± 2 °C, 14-h photoperiod, 3000 lux Medium: (a) MS + 1 mg liter−1 NAA for rooting (b) MS + 1 mg liter−1 BAP, 0.5 mg liter−1 NAA, for multiplication and rooting in one step In vitro rooting and hardening The excised axillary shoots can be rooted in a semisolid medium of half-strength MS salt and 0.5% activated charcoal for 1 week, followed by subculturing in onehalf MS medium containing 1.5 mg liter−1 IBA under a light intensity of 3500 lux (Reghunath and Bajaj 1992). Rooted shoots were transferred to MS one-half liquid medium containing only mineral salts and were then shifted to a greenhouse for hardening. For planting, vermiculite-fine sand (1:1) mixture was found to be the best, giving 92% establishment (Reghunath and Bajaj 1992). 2.2.4.8  Callus Culturing and Somaclonal Variations Callus regeneration protocols are important for generating somaclonal variations for future crop improvement. An efficient system for callus regeneration is essential for the production of a large number of somaclones, and such a system has been reported by Rao et al. (1982). The system was standardized at IISR (Ravindran et al. 1997). High variability was noticed in the case of morphological characters in somaclones in the culture vessel itself (Ravindran et al. 1997). The most striking morphological variant is a needle-leaf one having small needle-shaped leaves that multiply and root profusely in the same modified MS medium. But its rate of establishment in the nursery and field is reported to be low (Nirmal Babu, personal communication). Nirmal Babu and his colleagues have standardized a cell culture system for large-scale production of callus through somatic embryogenesis to enhance genetic variability. These somaclones are being tested for resistance to viruses and for other characters (Nirmal Babu, unpublished). A graphic depiction of the tissue culture cycle in cardamom (after Ravindran et al. 1997) is shown in Fig. 2.1.

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Explant

Stage 1–4 weeks

Mature plant Culture establishment

Hardening

Stage 4–5 weeks

Simultaneous shoot and root proliferation 6 weeks

Rooting

Stage 2–5 weeks Axillary branching Stage 3–8 weeks

Fig. 2.1  Tissue culture cycle in cardamom (Ravindran et al. 1997)

2.2.4.9  Field-Testing of Tissue-Cultured Plants The earliest report on field-testing of tissue-cultured (TC) plants was that of Lukose et al. (1993), although Nadgauda et al. (1983) had considered the field establishment of TC plants of cardamom. Lukose et al. carried out two statistically laid out trials to evaluate TC plants together with suckers and seedlings. The first trial was conducted with Clone-37 and the second with the cultivar Mudigere-1. Variations observed among TC plants, suckers, and seedlings were nonsignificant for most of the vegetative characters, as shown by analyzing pooled data of 4 years. Yielding tillers, panicles per plant, green capsule yield, and cumulative yield were significantly greater in TC plants in both trials. The earlier differences observed in growth characters disappeared during later years. Sudarshan et  al. (1997) reported the results of a large-scale evaluation carried out by the Indian Cardamom Research Institute. In one case, eight high-yielding micropropagated clones and their open-­ pollinated progenies were evaluated for performance at 56 locations in an area of 37.5  ha. Unfortunately, suckers were not included in the trial. Variability was observed in the clonal population for vegetative characters. The overall variability in TC plants was 4.5%, as against 3%, in open-pollinated seedling progenies for a given set of characters. Also, complete sterility was reported in certain clones. Microcapsules were significantly more in TC plants, accounting for a major share of variation in these plants, which was 8.4%. However, despite variations, TC plants had a 34% higher yield than open-pollinated seedlings. Among the reasons for variations were adventitious bud formation during micropropagation via axillary buds, genetic instability of adventitious meristem, and tissue culture-induced disorganization of meristems (Sudarshan et al. 1997). Chandrappa et al. (1997) tested eight TC

2.2  Crop Improvement

33

cardamom selections against their suckers and against two local checks 92:1997a, b. Of the clones, TC 5, TC 6, and TC 7 were found promising, and they differed among themselves inasmuch as yield, and other yield attributes were concerned. TC 5 was the best, recording superior values for most observations.

2.2.5  In Vitro Conservation In vitro conservation is an alternative method for medium-term conservation. An in vitro gene bank will be a safe alternative in protecting the genetic resources from epidemic diseases. Geetha et al. (1995) and Nirmal Babu et al. (1994, 1997) reported the conservation of cardamom germplasm in an in vitro gene bank by slow growth. The two sets of researchers carried out various trials to achieve an ideal culture condition under which growth is slowed down to the minimum without affecting the physiology or genetic makeup of the plant. The slow growth is achieved by the incorporation of agents for increasing the osmotic potential of the medium, such as mannitol. Half-­ strength MS without growth regulators and with 10 mg liter−1 each of sucrose and mannitol was found to be the best medium for in vitro storage of cardamom under slow growth. By using this medium in screw-capped vials, the subculture interval could be extended up to 1 year or more when incubated at 22 ± 2 °C at 2500 lux for a photoperiod of 10 h. Low-temperature storage at 5 and 10 °C was found to be lethal for cardamom, with the cultures lasting no more than 3  weeks (Geetha et al. 1995). Additional research in biotechnology deals with the following issues: (a) Isolation and culture of protoplast: Protoplasts could be isolated from mesophyll tissues collected from in  vitro-grown plantlets, achieving a yield of 35 × 105 g−1 of leaf tissue on incubation in an enzyme solution containing 0.5% macerozyme R 10, 2% Onozuka cellulase R 10, and 9% mannitol for 18–20 h at 25 °C in darkness (Geetha et al. 2000; IISR 1996). The yield of protoplasts from cell suspension culture was 1.5  ×  105  g−1 tissue when incubated in 1% macerozyme R 10 and 2% Onozuka cellulase R 10 for 24 h at 25 °C with gentle shaking at 53 rpm in darkness. The viability of the protoplast was 75% (mesophyll) and 40% (cell suspension). On culturing, the protoplasts developed into microcalli (Geetha et al. 2000). (b) Cryoconservation: Cryoconservation of cardamom seed was first attempted by Chaudhary and Chandel (1995), who tried to conserve seeds at ultralow temperatures either (1) by suspending the seeds in cryovials in the vapor phase of liquid nitrogen (−150 °C) by slow freezing or (2) by direct immersion in liquid nitrogen (−196 °C) by fast freezing. The frozen seeds were found to possess 7.7–14.3% moisture content, which meant that they could be successfully cryopreserved. The seeds also showed more than 80% germination when tested after 1 year of storage in the vapor phase of liquid nitrogen at 150 °C.

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(c) Synthetic seeds: The first report of synthetic seed production by encapsulation of shoot tips, encapsulated shoot tips of cardamom variety Malabar, isolated from multiple shoots and encapsulated in 3% w/w sodium alginate, with different gel matrices, and subsequently cultured in MS medium. Sajina et al. (1997) reported the standardization of synthetic seed production in many species, including cardamom. Synthetic seeds have many advantages over those germinated by the normal micropropagation methods. Synthetic production is an ideal system for conservation and exchange.

2.2.6  Conclusions Despite the fact that cardamom is a native of South India and has been used for many centuries, there still exist many gaps in our true understanding of this plant. Cardamom botany has been researched only superficially. The plant’s developmental morphology and physiology have been neglected, and its production physiology merits a thorough investigation. Information on the origin of even a single species of cardamom and on interrelationships among the various species is practically nonexistent. Questions, such as how far Indian species are related to Sri Lankan or Malaysian species, are not at all answered. All of these issues merit further studies. In the area of crop improvement, emphasis must be placed on developing lines that are resistant to drought, a major constraint on yield. Heterosis has not been exploited, and to do so, genetically homozygous lines need to be evolved. Attempts to develop a protocol for another culture and the production of haploids and dihaploids in cardamom are underway at IISR, Calicut. One of the most pressing areas for research is breeding for disease resistance, especially against the devastating viral diseases. Biotechnology can contribute much in this area. Yet another area of considerable importance is the molecular characterization of cardamom germplasm. Concerted efforts are required in this area. The alleviation of production constraints through conventional breeding or through molecular approaches will go a long way toward enhancing and sustaining productivity.

References Abheywickrama BA (1959) A provisional checklist of the flowering plants of Ceylon. Ceylon J Sci (Biol Sec) 2:119–240 Abraham P, Thulasidas G (1958) South Indian cardamom and their agricultural value. Indian Council of Agricultural Research Bulletin, vol 79. ICAR, New Delhi, pp 1–27 Anon (1958) South Indian cardamoms: their evolution and natural relationships Tech Bull 57. ICAR, New Delhi. Anon (1986a) Annual report 1986. ICRI, Myladumpara, pp 51–53 Anon (1986b) Annual report. ICRI, Spices Board, India Anon (1986c) Cardamom cultivation. Cardamom Board, Cochin, p 11

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Anon (1987) Annual report. ICRI, Spices Board, India Bajaj YPS, Furmanova M, Olszowska O (1988) Biotechnology of the micro-propagation of medicinal and aromatic plants, vol I. Springer, Berlin, pp 60–103 Bavappa, K.V.A., 1986. Research at CPCRI. Tech Bull, CPCRI, Kasaragod. p. 34 Belavadi VV, Parvathi C (1998) Estimation of honey bee colonies required for effective pollination in cardamom. In: Proceedings of the national symposium on diversity of social insects and other anthropods and the functioning ecosystems. III Congress of IUSSI, Mudigere, p 30 Belavadi VV, Chandrappa HM, Shadakshari YG, Parvathi C (1993) Isolation distance for seed gardens of cardamom (Elettaria cardamomum Maton). In: Veeresh GK, Umashanker R, Ganeshan KN (eds) Pollination in tropics, pp 241–243 Belavadi VV, Venkateshalu VV, Vivek HR (1997) Significance of style in cardamom corolla tubes for honeybee pollination. Curr Sci 73:287–290 Belavadi VV, Parvathi C, Raju B (1998) Optimal foraging by honey bees on cardamom. In Proceedings of XIII plantation crops symposium, December 16–18, Coimbatore, India (abstract) Bernhard RA, Wijesekera ROB, Chichester CO (1971) Terpenoids of cardamom oil and their comparative distribution among varieties. Phytochemistry 10:177–184 Burtt BL (1980) Cardamom and other Zingiberaceae in Hortus Malabaricus. In: Manilal KS (ed) Botany and history of Hortus Malabaricus. Oxford/IBH, New Delhi, pp 139–148 Burtt BL, Smith RM (1983) Dassanayake, M.D. A revised hand book to the flora of Ceylon, vol IV. Amerind Pub, New Delhi Chandran K, Raja P, Joseph D, Suryanarayana MC (1983) Studies on the role of honeybees in the pollination of cardamom. In: Proceedings of 2nd international conference on apiculture tropical climates, pp 497–504 Chandrappa HM, Shadakshari YG, Sudharsan MR, Raju B (1997) Preliminary yield trial of tissue cultured cardamom selections. In: Edison S, Ramana KV, Sasikumar B, Nirmal Babu K, Eapen SJ (eds) Biotechnology of spices, medicinal and aromatic plants. Indian Society of Spices, Calicut, pp 102–105 Chandrappa HM, Shadakshari YG, Dushyandhakumar BM, Edison S, Shivashankar KT (1998) Breeding studies in cardamom (Elettaria cardamomum Maton). In: Mathew NM, Jacob CK (eds) Developments in plantation crops research. Allied Pub., New Delhi, pp 20–27 Chaudhary R, Chandel KPS (1995) Studies on germination and cryopreservation of cardamom (Elettaria cardamomum Maton.) seeds. Seed Sci Biotechnol 23:235–240 Dandin SB, Madhusoodanan KJ, George KV (1981) Cardamom descriptor. In: Proceedings of 1Vth symposium plantation crops (Placrosym–1V), CPCRI, Kasaragod, India, pp 401–406 Gaertner (1791) Quoted from Abheywickrama (1959) Geetha SP, Manjula C, Sajina A (1995) In vitro conservation of genetic resources of spices. In: Proceedings of the Kerala Science Congress, Palakkad, pp 12–16 Geetha SP, Nirmal Babu K, Rema J, Ravindran PN, Peter KV (2000) Isolation of protoplasts from cardamom (Elettaria cardamomum Maton.) and ginger (Zingiber officinale Rosc.). J Spices Aroma Crops 9:23–30 George KV, Dandin SB, Madhusoodanan KJ, Koshy J (1981) Natural variations in the yield parameters of cardamom (Elettaria cardamocmum). In: Visveshwara S (ed) Proceedings of PLACROSYM 1981. ISPS, Kasaragod, pp 216–231 Gopal R, Chandraswamy DW, Nayar NK (1990) Correlation and path analysis in cardamom. Indian J Agric Sci 60:240–242 Gopal R, Chandraswamy DW, Nayar NK (1992) Genetic basis of yield and yield components in cardamom. J Plant Crop 20(Suppl):230–232 Holttum RE (1950) The zingiberaceae of the Malay Peninsula. Garden’s Bull Singapore 13:236–239 IISR (1996) Annual report for 1995–1996. Indian Institute of Spices Research, Calicut, pp 66–67 IISR (NRCS) (1997–1998) Annual report (1997–1998). Indian Institute of Spices Research, Calicut, India

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Jackson BP, Snowdon DW (1990) Atlas of microscopy of medicinal plants. Culinary herbs and spices. Belhaven Press Korikanthimath VS, Mulge R (1998) Assessment of elite cardamom lines for dry matter distribution and harvest index. J Med Aroma Plant 20:28–31 Korikanthimath VS, Rao GS (1993) Leaf area determination in cardamom (Elettaria cardamomum). J Plant Crop 11:151–153 Krishnamurthy K, Khan MM, Avadhani KK, Venkatesh J, Siddaramaiah AL, Chakravarthy AK, Gurumurthy SR (1989a) Three decades of cardamom research at regional research station, Mudigere (1958–1988). Technical Bulletin No. 2. Regional Research Station, Mudigere, Karnataka, India, p 94 Krishnamurthy K, Khan MM, Avadhani KK, Venkatesh J, Siddaramaiah AL, Chakravarthy AK, Gurumurthy BR (1989b) The decades of cardamom research at R. R. S. Mudigere. Technical Bulletin. University of Agricultural Sciences, Bangalore, India Kulandaivelu G, Ravindran KC (1982) Physiological changes in cardamom genotypes exposed to warm climate. J Plant Crop 20(Suppl):294–296 Kumar KB, Kumar PP, Balachandran SM, Iyer RD (1985) Development of clonal plantlets in cardamom (Elettaria cardamomum). J Plant Crop 13:31–34 Kuruvilla KM, Madhusoodanan KJ (1988) Effective pollination for better fruit set in cardamom. Spice India 1(6):19–21 Kuruvilla KM, Sudharshan MR, Madhusoodanan KJ, Priyadarshan PM, Radhakrishnan VV, Naidu R (1992) Phenology of tiller and panicle in cardamom (Elettaria cardamomum Maton.). J Plant Crop 20(Suppl):162–165 Kuttappa KM (1969) Capsule shedding in cardamom. Cardamom News 3(5):2–3 Lukose R, Saji KV, Venugopal MN, Korikanthimath VS (1993) Comparative field performance of micropropagated plants of cardamom. (Elettaria cardamomum). Indian J Agric Sci 63:417–418 Mabberley DJ (1987) The plant book. Cambridge University Press, Cambridge Madhusoodanan KJ, Radhakrishnan VV (1996) Cardamom breeding in Kerala. Breeding of crop plants in Kerala. University of Kerala, Trivandrum, pp 73–81 Madhusoodanan KJ, Sudharshan MR, Priyadarshan PM, Radhakrishnan VV (1990) Small cardamom: botany and crop improvement. In: Cardamom production technology. ICRI, Spices Board, India, pp 7–13 Madhusoodanan KJ, Kuruvilla KM, Potty SN (1998) Cardamom hybrids for higher yield and better quality capsule. Spice India 11(3):6–7 Madhusoodanan KJ, Radhakrishnan VV, Kuruvilla KM (1999) Genetic resources and diversity in cardamom. In: Sasikumar B, Krishnamoorthy B, Rema J, Ravindran PN, Peter KV (eds) Biodiversity, conservation, and utilization of spices, medicinal and aromatic plants. IISR, Calicut, pp 68–72 Mayne WW (1951) Report on cardamom cultivation in South India. ICAR Tech Bull 50. ICAR Publication, New Delhi, p 62 Melgode E (1938) Cardamom I Ceylon-Part 1. Trop Agric 91:325–328 Nadgauda R, Mascarenhas AF, Madhusoodanan KJ (1983) Clonal multiplication of cardamom (E. cardamomum Maton.) by tissue culture. J Plant Crop 11:60–64 Nair KC, Vijayan PK (1973) A study on the influences of plant hormones on the reproductive behaviour of cardamom. Agric Res J Kerala 11:85 Nirmal Babu K, Geetha SP, Manjula C, Ravindran PN, Peter KV (1994) Medium term conservation of cardamom germplasm: an in vitro approach. In: Proceedings of II Asia-Pacific conference on agricultural biotechnology, Madras, India, p 51. (abstract) Nirmal Babu K, Ravindran PN, Peter KV (1997) Protocols for micropropagation of spices and aromatic crops. Indian Institute of Spices Research, Calicut Owen TC (1901) Notes on cardamom cultivation Padmini K, Venugopal MN, Korikanthimath VS (1999) Biodiversity and conservation of cardamom (Elettaria cardamomum Maton.). In: Sasikumar B, Krishnamoorthy B, Rema J, Ravindran PN,

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Peter KV (eds) Biodiversity, conservation and utilization of spices, medicinal and aromatic plants. IISR, Calicut, pp 73–78 Padmini K, Venugopal MN, Korikanthimath VS, Anke Gowda SJ (2000) Studies on compound panicle type in cardamom (Elettaria cardamomum Maton.). In: Rajkumar R (ed) Recent advances in plantation crops research. Allied Pub., New Delhi, pp 97–99 Panchaksharappa MG (1966) Embryological studies in some members of Zingiberaceae II. Eleattaria cardamomum, Hitchenia, Caulna and Zingiber macrostachyum. Phytomorphology 16:412–417 Parameshwar NS, Venugopal R (1974) Capsule setting studies in Elettaria cardamomum. Maton Curr Res 3(5):57–58 Parameswar NS (1973) Floral biology of cardamom (Elettaria cardamomum Maton.). Mysore J Agric Sci 7:205–213 Parameswar NS (1977) Intergeneric hybridization between cardamom and related genera. Curr Sci 6:10 Parry JW (1969) Spices, vol II. Chemical Pub. Co., New York Parvathi C, Shadakshari YG, Belavadi VV, Chandrappa HM (1993) Foraging behaviour of honeybees on cardamom (Elettaria cardamomum Maton.). In: Veeresh GK, Umashanker R, Ganesan KN (eds) Pollination in tropics. IUSSI, Bangalore, pp 99–103 Patel DV, Kuruvilla KM, Madhusoodanan KJ, Potty SN (1997) Regression analysis in small cardamom. In: Proceedings of symposium on tropical crop research and development, Trichur, India. (in press) Patel DV, Kuruvilla KM, Madhusoodanan KJ (1998) Correlation studies in small cardamom (Elettaria cardamomum Maton.). In: Mathew NM, Jacob CK (eds) Developments in plantation crops research. Allied Pub., New Delhi, pp 16–19 Pattanshetty HV, Prasad ABN (1976) Blossom biology, pollination and fruit set in cardamom. In: Chadha KL (ed) Proceedings of international symposium on subtropical and tropical horticulture, vol 1. Today and Tomorrow’s Publishers, New Delhi Pillai PK, Santha Kumari S (1965) Studies on the effect of growth regulators on fruit setting in cardamom. Agric Res J Kerala 3:5–15 Pradip Kumar K, Mary Mathew K, Rao YS, Madhusoodanan KJ, Potty SN (1997) Rapid propagation of cardamom through in vitro techniques. In: Proceedings of 9th Kerala Science Congress Trivandrum, Kerala, India, p 185 Priyadarshan PM, Zachariah PK (1986) Studies on in vitro culture on cardamom (Elettaria cardamom Maton, Zingiberaceae): progress and limitations. In: Proceedings of international congress plant tissue and cell culture, Minnesota, USA, p 107. (abstract) Priyadarshan PM, Kuruvilla KM, Madhusoodanan KJ (1988) Tissue culture technology: impacts and limitations. Spice India 1(6):31–35 Priyadarshan PM, Kuruvilla KM, Madhusodanan KJ, Naidu R (1992) Effect of various media protocols and genotype specificity on micropropagation of cardamom (Elettaria cardamomum Maton.). In: Subba Rao NS, Rajagopalan C, Ramakrishna SV (eds) New trends in biotechnology. Oxford and IBH Publications, New Delhi, pp 109–117 Rajapakse LS (1979) G.L.C Study of the essential oil of wild cardamom oil of Sri Lanka. J Sci Food Agric 30:521–527 Ranjithakumari BD, Kuriachan PM, Madhusoodanan KJ, Naidu R (1993) Studies on light requirements of cardamom nursery. J Plant Crop 21(Suppl):360–362 Rao NSK, Narayana Swamy S, Chacko EK, Doreswamy ME (1982) Regeneration of plantlets from callus of Elettaria cardamomum Maton. Proc Indian Acad Sci 91(B):37–41 Ravindran PN, Rema J, Nirmal Babu K, Peter KV (1997) Tissue culture and in vitro conservation of spices: an overview. In: Edison S, Ramana KV, Sasikumar B, Nirmal Babu K, Eapen SJ (eds) Biotechnology of spices, medicinal and aromatic plants. Indian Society for Spices, Calicut, pp 1–12 Reghunath BR (1989) In vitro studies on the propagation of cardamom (Elettaria cardamomum Maton). Ph.D. thesis, Kerala Agric. University, Trichur, India

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Reghunath BR, Bajaj YPS (1992) Micropropagation of cardamom. In: Bajaj YPS (ed) Biotechnology in agriculture and forestry: high-tech and micropropagation III. Springer, Berlin, pp 175–198 Reghunath BR, Gopalakrishnan PK (1991) Successful exploitation of in vitro culture techniques for rapid clonal multiplication and crop improvement in cardamom. In: Proc Kerala Sci Cong Kozhikode, pp 70–71. Ridley HN (1912) Spices. McMillan & Co. Ltd., London Rijekbusch PAH, Allen DJ (1971) Cardamom in Tanzania. Acta Hortic 21:144–150 Rubido JF (1967) Prospects of cardamom growing Gautemala. Revista Cafeteria Gautemala 71:10–13 Sajina A, Minoo D, Geetha SP, Samsudheen K, Rema J, Nirmal Babu K et al (1997) Production of synthetic seeds in a few spices crops. In: Edison S, Ramana KV, Sasikumar B, Nirmal Babu K, Eapen SJ (eds) Biotechnology of spices, medicinal and aromatic plants. Indian Society of Spices, Calicut, pp 65–69 Sakai S, Nagamasu H (2000) Systematic studies of Bornean Zingiberaceae. II.  Elettaria of Sarawak. Edinb J Bot 57:227–243 Sastri BN (1952) The wealth of India: raw materials, (D-E), 150–160 Siddagangaih, Krishnakumar V, Naidu R (1993) Effect of chloremquat, daminozide, ethephon and maleic hydrazide on certain vegetative characters of cardamom (Elettaria cardamomum Maton.) seedlings. Spices Aroma Crops 2:53–59 Stone GN, Willmer PG (1989) Pollination of cardamom in Papua New Guinea. J Agric Res 28(4):228 Sudarshan MR, Kuruvilla KM, Madhusoodanan KJ (1988) Productivity phenomenon in cardamom and its importance in plantation management. Spice India 1(6):14–21 Sudarshan MR, Kuruvilla KM, Madhusoodanan KJ (1991) AS key to the identification of types in cardamom. J Plant Crop 18:52–55 Sudarshan MR, Bhatt SS, Narayanaswamy M (1997) Variability in the tissue cultured cardamom plants. In: Edison S, Ramana KV, Sasikumar B, Nirmal Babu K, Eapen SJ (eds) Biotechnology of spices, medicinal and aromatic plants. Indian Society for Spices, Calicut, pp 98–101 Trease GE, Evans WC (1983) Pharmacognosy, 12th edn. Baillere Tindall, London Vasanthakumar K, Mohanakumaran N (1998) Synthesis and translocation of photosynthates in cardamom. J Plant Crop 17:96–100 Vasanthakumar K, Mohanakumaran N, Narayanan CS (1989) Quality evaluation of three selected cardamom genotypes at different seed maturity stages. Spice India 2:25 Vatsya B, Duiesh K, Kundapurkar AR, Bhaskaran S (1987) Large scale plant formation of cardamom (Elettaria cardamomum) by shoot tip cultures. Plant Physiol Biochem 14:14–19 Wallis TE (1967) Textbook of pharmacognosy, 4th edn. J&A Churchill, London Willis JC (1967) A dictionary of the flowering plants and ferns, 7th edn. Cambridge University Press

Chapter 3

Cardamom Chemistry

Abstract  The chapter discusses, at length, the chemistry of cardamom, with special reference to the principal components of cardamom volatile oil, biosynthesis of flavor compounds, cardamom oleoresins, and extract. It also discusses biosynthesis of flavor compounds and evaluation of flavor quality. Keywords  Chemistry · Volatile oil · Biosynthesis · Extract · Cardamom oil

There are three forms in which cardamom is used for flavoring: whole, decorticated seeds, and fully ground into powder. Cardamom is distilled for essential oils and solvent extracted for oleoresin. In international trade, whole cardamom is generally the item of commerce. Trade in decorticated form is small, while that in powdered form is practically negligible. The aroma and flavor of cardamom are obtained from the essential oils. As early as 1908, there were reports that cardamom contained terpinene, sabinene, limonene, 1,8-cineole, α-terpineol, α-terpinyl acetate, terpinen-­4yl formate, and acetate and terpinen-4-ol (Guenther 1975). The characteristic odor and flavor of cardamom are determined by the relative composition of the ingredients of the volatile oil (Tables 3.1 and 3.2). The dried fruit of cardamom contains steam-volatile oil, fixed fatty oil, pigments, proteins, cellulose, pentosans, sugars, starch, silica, calcium oxalate, and minerals. The major constituent of the seed is starch, up to 50%, while the crude fiber constitutes up to 31% of the fruit husk. The constituents of the spice differ among varieties and with variations in environmental conditions of growth, harvesting, drying procedures, and subsequent duration, as well as conditions of storage. The main factor that determines the quality of cardamom is the content and composition of volatile oil, which determine the fruit’s flavor and aroma. Fruit color does not affect intrinsic organoleptic characteristics. However, a faded fruit color generally indicates a product stored for a longer period and, possibly, deterioration in the organoleptic characteristics through evaporation of the volatile oil (Purseglove et al. 1981). Cardamom oil is produced commercially by steam distillation of powdered fruits. The yield and the organoleptic properties of the essential oil so obtained are dependent on many factors. Fruits from recent harvests yield more oil than oil obtained from fruits stored for a long period. To obtain full recovery of essential oil, © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2020 K. P. Nair, The Geography of Cardamom (Elettaria cardamomum M.), https://doi.org/10.1007/978-3-030-54474-4_3

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Table 3.1 The principal components of cardamom volatile oil

Component Total oil (%) α-Pinene 1.5 β-Pinene 0.2 Sabinene 2.8 Myrcene 1.6 α-Phellandrene 0.2 Limonene 11.6 1,8-Cineole 36.3 Terpinene 0.7 Cymene 0.1 Terpinolene 0.5 Linalool 3.0 Linalyl acetate 2.5 Terpinen-4-ol 0.9 α-Terpineol 2.6 α-Terpinyl acetate 31.3 Citronellol 0.3 Nerol 0.5 Geraniol 0.5 Methyl eugenol 0.2 Trans-nerolidol 2.7

Table 3.2  Specification of volatile oil Definition, source

Physical and chemical constraints Descriptive characteristics

Containers and storage

Volatile oil distilled from seeds of Elettaria cardamomum (Linn.) Maton. Family: Zingiberaceae; cardamom grown in South India, Sri Lanka, Guatemala, Indonesia, Thailand, and South China Appearance: Colorless to very pale-yellow liquid. Odor and taste: aromatic, penetrating, somewhat camphoraceous odor, persistently pungent, strongly aromatic taste. Specific gravity: 0.917–0.947 at 25 °C; optical rotation: +22° to +44°; refractive index: 1.463–1.466 at 20 °C Solubility: 70% alcohol in five volumes, occasional opalescence Benzyl alcohol: in all proportions Diethyl phthalate: in all proportions Fixed oil: in all proportions Glycerin: insoluble Mineral oil: soluble with opalescence Propylene glycol: insoluble Stability: unstable in the presence of strong alkali and strong acids; relatively stable to weak organic acids; affected by light Glass, aluminum, or suitably lined containers, filled full or tightly closed and stored in a cool place, protected from light

at least 4-h extraction is essential. Industrial production of cardamom oleoresin is carried out on a relatively smaller scale. Solvent extraction yields about 10% oleoresin, and the content depends on the solvent and raw material used. Cardamom oleoresin contains about 52–58% volatile oil (Purseglove et al. 1981). Oleroresin is used to flavor the fruit and is normally dispersed in salt, flour, rusk, or dextrose before use.

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The principal components of cardamom oil are given in Table 3.1. The volatile oil is extracted from the seeds, and the husks hardly give 0.2% oil. Even though the public perception about good-quality cardamom is that it comes from the greenish seed capsule, the appearance of the capsule has but little to do with the recovery of volatile oil (Sarath Kumara et  al. 1985). The husk provides good protection and prevents the seeds from losing oil. Loss of oil from dehusked seeds is rapid: Seeds start losing oil the moment husk is removed, and the loss increases with storage time. Bleached cardamom tends to lose oil faster, as the husk becomes very brittle due to bleaching. Oil from freshly separated seeds and oil from whole capsules (seeds and husk) are almost identical (Govindarajan et al. 1982). Steam distillation is being adopted for oil extraction by most commercial units in India and elsewhere. Cryogrinding using liquid nitrogen is ideal for preventing the loss of volatile oil during grinding. Supercritical extraction using liquid carbon dioxide is known to extract more oil, and the flavor is closer to that of natural cardamom. In oil extraction, the early fractions are rich in low-boiling terpenes and 1,8-cineole, and the later fractions are rich in esters. Volatile oil content is highest 20–25 days before full maturity. The ratio of the two main components, 1,8-cineole and α-terpinyl acetate, determines the critical flavor of the oil. The volatile oil from var. Malabar represented by “Coorg Greens” is more “camphory” (smells close to the way camphor smells) in aroma because of the relatively higher content of 1,8-cineole. This oil is reported to be ideal for soft drinks. Early fractions during distillation are dominant in low-boiling monoterpenes and 1,8-cineole. Techniques are available to remove these fractions by fractional distillation so that the remaining oil will have more of α-terpinyl acetate, which contributes to the mildly herbaceous, sweet spicy flavor of the fruit, a flavor that is predominant in var. Mysore or the commercial grade, popularly known as the “Alleppey Green” (Govindarajan et al. 1982). Eighteen export grades of Indian cardamom, as certified by Agmark (a prominent certification agency in India), were evaluated for their physical and chemical properties (Mathai 1985). Grades with bigger and heavier capsules— “Alleppey Green Extra Bold” (AGEB) and “Coorg Green Extra Bold” (CGEB)— were inferior in their flavor constitution, compared with the medium capsule grade (“Alleppey Green Small,” AGS). Chemical bleaching of the capsules reduced the amount of essential oil in them. Vasanthakumar et al. (1989) reported that cardamom at the black-seed stage, or “karimkai” (the Malayalam word meaning “black seed”), is ideal for consumption and essential oil extraction. Gopalakrishnan et al. (1989) reported that thrips-infested cardamom capsules contained a relatively higher percentage of 1,8-cineole. Nirmala Menon et  al. (1999) extracted bound aroma compounds from fresh green cardamom; the free volatiles were isolated with ether/pentane (1:1) mixture and the bound compounds with methanol. The major compounds in the aglycone fraction were identified as 3-methyl-pentan-2-ol, linalool, and cis- and trans-isomers of nerolidol and farnesol. Noleau and Toulemonde (1987) reported the presence of 122 compounds in cardamom oil cultivated in Costa Rica. The identification of 122 compounds was the first-ever discovery for these authors.

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3.1  Biosynthesis of Flavor Compounds 3.1.1  Sites of Synthesis The accumulation or secretion of monoterpenes and sesquiterpenes is always associated with the presence of well-defined secretory structures such as oil cells, glandular trichomes, oil or resin ducts, or glandular epidermis. A common feature of these secretory structures is an extra cytoplasmic cavity in which the relatively toxic terpinoid cells and resins appear to be sequestered. This anatomic feature distinguishes the essential oil plants from others in which terpenes are produced as trace constituents that either volatilize inconspicuously or are rapidly metabolized. Several pieces of evidence indicate that the secretory structures are also primary sites of mono- and sesquiterpene biosynthesis (Francis and O’Connell 1969).

3.1.2  Biological Function The monoterpenes and sesquiterpenes traditionally have been regarded as functionless metabolic waste products. Yet, certain studies have shown that these compounds can play varied and important roles in mediating the interactions of plants with their environment. The monoterpenes 1,8-cineole and camphor have been shown to inhibit the germination and growth of competitors and thus act as allelopathic agents.

3.1.3  Early Biosynthetic Steps and Acyclic Precursors All plants employ the general, well-known isoprenoid pathway in the synthesis of certain essential substances. The monoterpenes and sesquiterpenes are regarded as diverging at the C10 and C15 stages, respectively, in biosynthetic pathways. The isoprenoid pathway begins with the condensation of 3-acetyl-CoA in two steps to form hydroxymethylglutaryl-CoA, which is reduced to mevalonic acid, the precursor of all isoprenoids. A series of phosphorylations and decarboxylation with elimination of the C-3 oxygen function (as phosphate) yields isopentenyl pyrophosphate (IPP) (McCaskill and Croteau 1995). The IPP is isomerized to dimethylallyl pyrophosphate (DMAPP), in turn leading to the synthesis of geranyl pyrophosphate (GPP) and farnesyl pyrophosphate (FPP). A number of monoterpene cyclases have been investigated in detail, especially the one responsible for the synthesis of α-terpinene, γ-terpinene, and 1,8-cineole. Other cyclizations of interest are the cyclization of geranyl pyrophosphate to limonene and the cyclization of geranyl pyrophosphate to sabinene, the precursor of C3 oxygenated thujene-type monoterpenes. The biosynthesis of thujene monoterpenes

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(such as 3-thujene) involves the photooxidation of sabinene and also involves α-terpineol and terpinen-4-ol as intermediates (Croteau and Sood 1985). The pathways of cyclization of geranyl phosphate and farnesyl pyrophosphate to the corresponding monoterpenes and sesquiterpenes are not similar. The limited information available suggests that monoterpene and sesquiterpene cyclases are incapable of synthesizing larger and smaller analogs. Pinene biosynthesis has been extensively studied. Three monoterpene synthases (cyclases) catalyze the conversion of GPP. Pinene cyclase I converts FPP into bicyclic (+)-α-pinene, (+)- β-pinene, and monocyclic and acyclic olefins (Bramley, 1997). The biosynthesis of monoterpenes, limonene, and carvone proceeds from geranyl diphosphate, which is cyclized to (+)-limonene by monoterpene synthase. The (+)-limonene is then either stored in the essential oil ducts without further metabolism or converted by limonene-6-­ hydroxylase to (+)-trans carveol. The latter is oxidized by a dehydrogenase to (+)-carveone (Brouwmeester et  al. 1998). Turner et  al. (1999) demonstrated the localization of limonene synthase. Studies in peppermint (Gershenzon et al. 2000) suggested that monoterpene biosynthesis is regulated by genes, enzymes, and cell differentiation. The biosynthesis of 1,8-cineole is suggested from linalyl pyrophosphate (Clark et al. 2000). Also known as eucalyptol, 1,8-cineole is a biosynthetic dead-end in many systems, thereby allowing the accumulation of large quantities of this compound in many plants. Other than its presence in cardamom oil, 1,8-cineole is also found in essential oils of artemisia, basil, betel leaves, black pepper, carrot leaf, cinnamon bark, eucalyptus, and many other essential oil-yielding plants. Most of the processes of terpenoid biosynthesis are associated with cell organelles. Calcium and magnesium play important roles in the biosynthesis of sesquiterpenes (Preisig and Moreau 1994). McCaskill and Croteau (1995) indicate that the cytoplasmic mevalonic acid pathway is blocked at HMG-CoA reductase and that the IPP utilized for both monoterpene and sesquiterpene biosynthesis is synthesized exclusively in the plastids.

3.2  Industrial Production Industrially, cardamom oil is extracted by steam distillation. The distillation unit consists of a material-holding cage, a condenser and receiver for steam distillation, and adoptive conditions for obtaining oil of acceptable quality. Usually, lower-grade capsules harvested after full maturity are used for steam distillation. Such capsules are first dehusked by shearing in a disk mill with wide distances between disks, and the seeds are separated by vibrating sieves. The dehusked seeds are further crushed to a coarse powder (Govindarajan et al. 1982). The essential oil-containing cells in cardamom seeds are located in a single layer below the epidermis, and fine milling will result in a loss of volatile oil. Cryogrinding using liquid nitrogen is ideal for preventing this loss. Research on steam distillation revealed that nearly 100% of the volatile oil was recovered in about 1 h time. The composition of the fractions

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collected at 15 min shows that most are hydrocarbons and 1,8-cineole distilled over, while 25–35% of the important aroma-contributing esters were also recovered during this period. Further distillation for 2 h was required to recover remaining esters. Hence, a distillation duration of 2–3 h was essential to completely extract the volatile oils. The value of cardamom as a food and beverage additive depends much on the aroma components, which can be recovered as volatile oil. The volatile oil has a spicy odor similar to that of eucalyptus oil. Oil yield ranges from 3 to 8% and varies with the variety of cardamom, maturity at harvest, commercial grade, freshness of the sample, whether the sample is green or bleached, and distillation efficiency.

3.2.1  History Composition: Nigam et al. (1965) reported the detailed analysis of cardamom for the first time. The constituents were identified with the help of gas chromatography and infrared spectroscopy, using authentic reference compounds and published data. Ikeda et al. (1962) reported that 23.3% of the oil was hydrocarbons with limonene as a major component. Ikeda’s group also reported the presence of methyl heptenone, linalool, linalyl acetate, β-terpineol, geraniol, nerol, neryl acetate, and nerolidol. Compounds present in commercial samples were identified and compared with those of the wild Sri Lankan cardamom oil (Richard et  al. 1971). Govindarajan et  al. (1982) elaborated the range of concentration of major flavor constituents, their flavor description, and their effect on flavor use. Thin-layer chromatography, column chromatography, and, subsequently, gas chromatography were employed to separate oil constituents. Fractional distillation, infrared spectroscopy, mass spectrum, and nuclear magnetic resonance were adopted to identify the specific compounds. The major constituents identified were α-pinene, α-thujene, β-pinene, myrcene, α-terpinene, γ-terpinene, and penta-cymene. These were identified in the monoterpene hydrocarbon fraction of cardamom oil. Different commercial cardamom samples were compared for their chemical constituents in 1966 and 1967 (1978). Sayed et al. (1979) evaluated the oil percentage in different varieties of cardamom. Varieties Mysore and Vazhukka contained the maximum (8%). The percentage by weight of cardamom seeds in the capsules ranged from 68 to 75%. Percentage of cardamom seeds is positively correlated with volatile oil (r = 0.436) on a dry-seed basis, whereas percentage of husk is negatively correlated with volatile oil (r = −0.436). Detailed investigations on the volatile oil revealed large differences in the 1,8-cineole content, as high as 41% in the oil of variety Malabar and as low as 26.5% in the oil of variety Mysore. Although the α-terpinyl contents were comparable, the linalool and linyl acetate were markedly higher in variety Mysore. The combination of lower 1,8-cineole with its harsh camphory note and higher linalyl acetate with its sweet, fruity floral odor results in the relatively pleasant mellow flavor in the variety Mysore, represented by the largest selling Indian cardamom

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grade, namely, Alleppey Green. Zachariah and Lukose (1992) and Zachariah et al. (1998) identified cardamom lines with relatively low cineole and high α-terpinyl acetate. An interesting observation is that lines Alleppey Green 221 and 223 gave a consistently higher oil yield (7.8%) and high α-terpinyl acetate content (55%). The performance of Alleppey Green 221 was consistent for about five seasons (Zachariah et al. 1998). Previous gas chromatograms showed up to 31–33% peaks, and up to 23 compounds were identified, whereas the improved procedure gave higher resolution with more than 150 peaks. Not all peaks have been identified. All results, however, confirm the earlier observations that 1,8-cineole and α-terpinyl acetate are the major components in cardamom oil. Many investigators used techniques that were a combination of fractional distillation, column and gas chromatography, mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance to identify the constituents in cardamom oil. Nirmala Menon et al. (1999) have investigated the volatiles of freshly harvested cardamom seeds by adsorption on Amberlite XAD-2 from which the free volatiles were isolated by elution with a pentane–ether mixture and glycosidically bound volatiles with methanol. Gas chromatographic–mass spectrometric analysis of the two fractions led to the identification of about 100 compounds. Among the free volatiles, the important ones are 1,8-cineole and α-terpinyl acetate. The less important ones are geraniol, α-terpineol, p-menth-8-­ en-2-ol, γ-terpinene, β-pinene, carvone oxide, and so on, while a large number of compounds were present in trace amounts. Among the aglycones, the important ones are 3-methylpentan-2-ol, α-terpineol, isosafrole, β-nerolidol, trans, trans-­ farnesol, trans, cis-farnesol, cis, trans-farnesol, T-muurolol, cubenol, 10-epi-­ cubenol, cis-linalool-oxide, and tetrahydrolinalool. Sixty-eight compounds were identified in the volatile fraction and 61 in the glycosidically bound fraction.

3.2.2  Evaluation of Flavor Quality The flavor quality of a specific food item results from the interaction of the chemical constituents contained in the food item with the taste perception of the person enjoying the item in question. As the second most important spice in the world, next only to black pepper, cardamom has as its most important component the volatile oil with its characteristic aroma, described as sweet, aromatic, spicy, camphory, and so on. Cardamom oil is rich in oxygenated compounds, all of which are potential aroma compounds. Capillary column chromatography and gas chromatography have identified 150 compounds in cardamom oil. While most of these compounds, which are alcohols, esters, and aldehydes, are commonly found in many spice oils, the dominance of the ether 1,8-cineole and the esters α-terpinyl and linalyl acetate in the composition renders the volatile oil contained in cardamom a unique one. The bitterness compound present in cardamom is α-terpinyl, present to the extent of about 0.8–2.7%. Govindarajan et  al. (1982) described the esters: 1,8-cineole ratio (Table  3.3). In rare samples, slightly oxidized “terpinic” compounds, which are

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Table 3.3  Ratios of esters and alcohol to 1,8-cineole in cardamom volatile oils Ratio Alfa-terpinyl Source acetate Alleppey Green (var. Mysore) 1.30 Alleppey Green (var. Mysore) 1.10 Kerala, Ceylon (var. Mysore) 0.83 Ceylon, commercial 1.21–1.77 Ceylon, from extract 1.67–2.40 Ceylon, green expressed (var. 1.69 Mysore) Ceylon, green from extract 2.40 Ceylon, green expressed (var. 2.17 Mysore) Coorg green (var. Malabar) 0.73

Alfa-terpinyl linalyl acetate 1.59 1.19 0.91 – – 1.80

Esters + linalool-­ terpineol 1.77 1.43 1.03 – – 1.91

2.64 2.40

2.83 2.68

0.77

0.80

Source: Govindarajan et al. (1982)

defective constituents, were observed at high dilution levels, but were overshadowed by total cardamom aroma at higher concentrations. Markedly camphory samples (lacking sweet, aromatic components) and samples that are high in defectives or oxidized terpinic, or that are resinous, oily, earthy, or bitter in flavor, are rated poor and unacceptable. The authors (Raghavan et al.) and (Govindarajan et al.) suggested that quality grading of cardamom is possible by observing three major attributes: balance of profile, intensity or tenacity, and absence of defects. The desirable and defective notes of cardamom oil are described in Table 3.4. The general profile of the popular Alleppey Green is described in Table 3.5. Analysis of a Japanese cardamom oil sample indicated the presence of some new compounds, including 1,4-cineole, cis-p-menth-2-en-1-ol, and trans-p-menth-2en-­1-ol, all of them in extremely low amounts of 0.1–0.2%. Cardamom oil from Sri Lanka gave a high range of values for α-pinene plus sabinene (4.5–8.7%) and for linalool (3.6–6%) and a wider range for the principal components: 1,8-cineole (27–36.1%) and α-terpinyl acetate (38.5–47.9%) (Govindarajan et al. 1982). Some compounds, such as α-thujene, sabinene, p-cymene, 2-undecanone, 2-tri-decanone, heptacosane, and cis- and trans-p-menth-2-en-1-ols, were rarely detected in cardamom samples. Components such as camphor, borneol, and citrals might modify the overall flavor quality of the spice, which is determined mainly by a combination of terpinyl and linyl acetate and cineole. Locations where the crop is grown alter the concentration of linalool, limonene, α-terpineol, and so on. The quality of flavor of a food depends on the interaction of the chemical constituents of the food with human taste buds, and the perception of taste by individuals depends on different attributes. A causal connection between physical and chemical characteristics of food and their sensory perception and judgment by human assessors has to be ascertained in order to establish a meaningful judgment of quality. According to many investigators, the ratio of 1,8-cineole to α-terpinyl acetate is a fairly good index of the purity and authenticity of cardamom volatile oil (Purseglove et al. 1981). The

3.2  Industrial Production Table 3.4  Flavor profile of cardamom oil and extracts

47 Desirable notes Fresh cooling Camphoraceous Green Sweet Spicy Floral Woody/Balsamic Herbal Citrus Minty Husky Astringent, weakly

Defective notes Unbalanced Sharp/Harsh Heavy Earthy Oily (vegetable) oxidized Resinous Oxidized terpinic Bitter

Source: Govindarajan et al. (1982) Note: The descriptions in capital letters are the perceived dominant characteristics; the defectives are arranged in the order of increasing impact on flavor

Table 3.5  Volatile oil profile of cardamom Origin Commercially distilled from Alleppey Green varieties Odor Initial impact Penetrating, slightly irritating Cineolic, cooling Camphoraceous, disinfectantlike, warm, spicy Sweet, very aromatic, pleasing Fruity, lemony, citruslike Persistence The oil rapidly “airs off” on being smelled, with its strip losing its freshness; becomes herby, woody, with a marked musty “back-note” Dry out No residual odor after 24 h Source: Heath (1978)

ratio is around 0.7–1.4. The Cardamom Research Center at Appangala, Coorg district in the state of Karnataka, India, under the administrative control of the Indian Institute of Spices Research, Calicut, Kerala State, India, in turn under the overall administrative control of the Indian Council of Agricultural Research at New Delhi, India, could collect many accessions with a flavor ratio of more than 1 from cardamom-­growing areas. Both 1,8-cineole and α-terpinyl acetate, together with terpene alcohols (linalool, terpinen-4-ol, and α-terpineol), are important for the evaluation of aroma quality. The oils from variety Malabar exhibit the lowest flavor ratio, whereas those from variety Mysore have a high flavor ratio. Cardamom samples from Sri Lanka and Guatemala have higher ratios than those from other countries, indicating their superiority in flavor, similar to that of variety Mysore. The occurrence of components such as borneol and citral modifies the flavor quality. Pillai et al. (1984) conducted a comparative study of the 1,8-cineole and α-terpinyl acetate contents of cardamom oils derived from diverse sources (Table 3.6). Their investigation indicated that Guatemalan cardamom oil is marginally superior to Indian cardamom oil because of the former’s higher content of α-terpinyl acetate content. The high concentration of 1,8-cineole makes the oil from PNG poor. The

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Table 3.6  Percentage of 1,8-cineole and terpinyl acetate in volatile oils of cardamom grown in different regions Origin Guatemala I Guatemala II Guatemalayan Malabar type Guatemalayan I Guatemalayan II Synthite (commercial grade) Mysore-type (Ceylon) Malabar-type (Ceylon) Mysore I Mysore II Mysore Malabar I Malabar II Ceylon type Alleppey I Alleppey Green Coorg Green Mangalore I Mangalore II Papua New Guinea (PNG) Cardamom oil (Indian origin)

Percentage of oil 1,8-cineole 36.40 38.00 23.40 39.08 35.36 46.91 44.00 31.00 49.50 41.70 41.00 28.00 43.50 36.00 38.80 26.50 41.00 56.10 51.20 63.03 36.30

Alfa-terpinyl acetate 31.80 38.40 50.70 40.26 41.03 36.79 37.00 52.50 30.60 45.90 30.00 45.50 45.10 30.00 33.30 34.50 30.00 23.20 35.60 29.09 31.30

Source: Pillai et al. (1984)

same investigators found a fair degree of concordance in the infrared spectra of oils, irrespective of their origin. These spectra provide a fingerprint of the oil as it projects the functional groups and partial structures that are present. The spectra also help in tracking the aging process of the oil. Extraction methods such as cryogenic grinding (Gopalakrishnan et al. 1991) and supercritical extraction also influence the flavor profile. Such techniques can extract the trace compounds that are otherwise lost in other methods of extraction.

3.2.3  Cardamom Oleoresins and Extract In a food, the total solvent extract or oleoresin is known to reflect the flavor quality more closely than the distilled volatile oil does. In the case of cardamom, oil more or less represents both flavor and taste. The stability of oleoresin depends on the changes that occur to the fat and terpenic compounds, which are usually susceptible to oxidative changes. Existing investigations point to the fact that there exists a clear

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difference in the flavor profile among cardamom varieties, which in turn is influenced by agroclimatic conditions, postharvest processing, and cultural practices.

3.2.4  Variability in Composition Analysis of germplasm collections conserved at the Indian Institute of Spices Regional Research Station at Appangala, Coorg district, Karnataka State, India, under the administrative control of the Indian Council of Agricultural Research in New Delhi, indicated a distinct variability in oil content and concentration of the two important components of the oil: α-terpinyl acetate and 1,8-cineole. Selective breeding of the high-quality accessions that have a low 1,8-cineole content and high α-terpinyl acetate content, such as Appangala 221 (AG 221), will go a long way toward enhancing the total flavor quality of Indian cardamom varieties.

3.2.5  Pharmaceutical Properties of Cardamom Oil Cardamom oil possesses both antibacterial and antifungal properties. The chemical composition, physicochemical properties, and antimicrobial activity of dried cardamom fruits used to assess the potential usefulness of cardamom oil as a preservative have been investigated by Badei et al. (1991a, b). The antimicrobial effect of the cardamom oil was tested against nine bacterial strains, one fungus, and one yeast, which together showed that the oil was as effective as 28.9% phenol. The minimal inhibitory concentration of the oil was 0.7 mg ml−1, and it was concluded that cardamom oil could be used at a minimal inhibitory concentration range of 0.5–0.9 mg ml−1 without any adverse effect whatsoever on flavor quality. Cardamom oil is effective as an antioxidant for cottonseed oil, as assessed by stability, peroxide number, refractive index, specific gravity, and rancid odor. The effect is enhanced by increasing the cardamom oil content in cottonseed from 100 to 5000  ppm. Organoleptic evaluation showed that the addition of up to 1000 ppm cardamom oil did not adversely affect the specific odor of cottonseed oil (Photo 3.1).

3.2.6  Fixed Oil of Cardamom Seeds In addition to containing volatile oil, cardamom seeds contain fixed fatty oil. The composition of fatty oil has been investigated and found to contain mainly oleic and palmitic acids (Table 3.7). Gopalakrishnan et al. (1990) carried out investigations based on nuclear magnetic resonance and mass spectroscopy and reported that the nonsaponifiable lipid fraction of cardamom consisted mainly of waxes and sterols.

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Photo 3.1  Dried cardamom Table 3.7  The fixed fatty oil composition of cardamom seed

Fixed fatty acid Oleic Palmitic Linoleic Linolenic Caproic Stearic Hexadecanoic Caprylic Capric Myristic Arachidic Hexadecanoic Pentadecanoic Lauric

Total fixed oil (%) 42.5–44.2 28.4–38.0 2.2–15.3 5.8 5.3 3.2 1.9 5.3