Walnut Germplasm Collections at CITH A Description of Walnut Collections
M. K. Verma, A.A. Sofi, N. Ahmed and D.B. Singh
Central Institute of Temperate Horticulture (Indian Council of Agricultural Research) Old Air Field, P.O.: Rangreth - 190 007 Srinagar, J&K (India)
Citation Verma, M.K., Sofi, A.A., Ahmed, N. and D.B. Singh 2009. Walnut Germplasm Collection at CITH. Central Institute of Temperate Horticulture, Srinagar, J&K
Compiled and Edited by M.K.Verma A.A. Sofi N. Ahmed D.B. Singh
Published by Prof. N. Ahmed Director Central Institute of Temperate Horticulture (Indian Council of Agricultural Research) Old Air Field, P.O.: Rangreth - 190 007 Srinagar, J&K (India)
Printed by M/s Royal Printers, A-89/1, Naraina Industrial Area Phase-I, New Delhi 110 012 Ph.: 011-25797524
Contents
Introduction ........................................................................................................................ 1 Botany ................................................................................................................................... 1 Species and Classification of Juglans ............................................................................ 4 Production Scenario .......................................................................................................... 6 Promising Selections made by CITH ............................................................................. 8 Exotic Walnut Cultivars.................................................................................................. 18
Introduction
T
his publication is the outcome of the walnut (Juglans regia L.) breeding program funded by National Agricultural Technology Project (NATP), Horticultural Technology Mission (HTM) and Institute. The description of the germplasm collection at the Central Institute of Temperate Horticulture, Srinagar, J&K is intended to be useful to plant breeders, walnut growers, farm advisors and general public. It contains information about some of the important breeding stock collected, propagated vegetatively and planted for further evaluation. The descriptions and illustrations of the selections are based on the data of the mother tree identified for tree growth, yield and qualitative traits of nut as well as kernel characters prescribed by IBPGR descriptor. The walnut field gene bank of CITH consists of genetic lines of special interest to yield and quality of nuts for domestic as well as export market including old and new cultivars and selected parental stock. This collection is the major source of walnut genetic resources of potential value for future walnut breeding at CITH. The collection is intended to serve as a source of material which is already adapted to Indian conditions and for studying and solving future problems in walnut culture. It also serves as a resource for student research, for growers and farm advisors and is for training and demonstrations. There are some 199 indigenous and exotic cultivars and selections mainly made by Central Institute of Temperate Horticulture. However, few of them are from Shere-Kashmir University of Agriculture Science and Technology-Kashmir (SKUAST-K), Dr. Y.S. Parmar University of Horticulture and Forestry-Solan, HP. The selections and cultivars botanically belong to Juglans regia (Persian or English, Indian walnut). All of which produce edible nuts having commercial importance for domestic as well as export market as inshell and kernel use. The Juglans regia is the most horticulturally developed and widely cultivated species. Specimens of the cultivars and numbered selections discussed here are located in the Walnut Block of CITH.
Botany Juglans regia (Common walnut, Persian walnut or English walnut), is the original walnut tree of the Old World. It is native in a region stretching from the Balkans eastward to the Himalayas and southwest China. Juglans regia is a large deciduous tree attaining heights of 25–35 m, and a trunk up to 2 m diameter, commonly with a short trunk and broad crown, though taller and narrower in dense forest competition. It is a light-demanding species, requiring full sun to grow well. The bark is smooth, olive-brown when young and silvery-grey on older branches, with scattered broad fissures with a rougher texture. Like all walnuts, the pith of the twigs contains air spaces, the chambered pith brownish in colour. The leaves are
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alternately arranged, 25-40 cm long, odd-pinnate with 5–9 leaflets, paired alternately with one terminal leaflet. The largest leaflets the three at the apex, 10–18 cm long and 6–8 cm broad; the basal pair of leaflets much smaller, 5–8 cm long, the margins of the leaflets entire. The male flowers are in drooping catkins 5–10 cm long, the female flowers terminal, in clusters of two to five, ripening in the autumn into a fruit with a green, semi-fleshy husk and a brown corrugated nut. The whole fruit, including the husk, falls in autumn; the seed is large, with a relatively thin shell, and edible, with a rich flavour.
Mature dormant tree Field gene bank at CITH
Immature nuts
Dormant male catkin
Young tree
Male catkins
Dormant current season
Female flower
Hollow pith
Source: W.P. Armstrong 2006
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Walnut Germplasm Collections at CITH
Though Juglans regia L. is self compatible, its dichogamy encourages allogamy. Thus, the genetic structure of the Persian walnut is fairly heterozygous. Cultivated varieties generally well adapted to climatic conditions of the different production areas, often lack some important agronomic characteristics. It is therefore useful to select in natural populations or create through hybridization new cultivars combining characters of improved climate adaptation (late budbreak, low chilling requirement or winter hardiness), early fruiting and high productivity of quality kernel traits (lateral fruitfulness), disease tolerance (blight and anthracnose), hyper susceptibility to cherry leaf roll virus, high fruit and kernel quality. This is possible given the very large and so far unexploited variability within the Juglans regia L. species. Hybridization programs to create new walnut varieties are relatively less developed than those of the other fruit species. The main programs are carried out at CITH (ICAR)- Srinagar, SKUAST-K, UHF-Solan, UC Davis (USA) and at the Fruit and Vine Research Station in Bordeaux (France). On the other hand, during the last decade, many prospections were carried out in natural populations in the main producer countries in particular in India, Greece, Iran, Italy, Morocco, Portugal, Romania, Spain, Turkey, and Yugoslavia. New interesting genitors or cultivars are beginning to be released from these breeding and selection works.
Walnut Germplasm Collections at CITH
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Species and Classification of Juglans The genus Juglans consists of approximately 20 species grouped taxonomically into four sections: Rhysocaryon, Cardiocaryon, and Trachycaryon, Dioscaryon. All these species are diploid with 2n = 2x = 32 chromosomes. The section of Rhysocaryon (black walnuts) is composed of 16 North and South American Juglans species. The most important are Juglans nigra L., Juglans hindsii Jeps and Juglans major Heller used as rootstocks of Persian walnut. The section of Cardiocaryon consists of species originating from Japan (Juglans sieboldiana Maxim), China (Juglans catchayensis Dode) and Mandchuria or the Korean peninsula (Juglans mandshurica Maxim) used as wood producers and sometimes as rootstocks. Juglans cinerea L. or butternut, the only species of the Trachycarion section is present in the forests of north-western Canada and USA. The section Dioscaryon consists solely of the commercially valuable Persian walnut, Juglans regia L. Juglans regia is native to the mountain ranges of Central Asia extending from Xinjiang province of western China, parts of Kazakhstan, Uzbekistan and southern Kirghizia and from mountains of Nepal, Tibet, northern India and Pakistan through Afghanistan, Turkmenistan and Iran to portions of Azerbaijan, Armenia, Georgia and eastern Turkey. In these countries, there is a great genetic variability in particular ancestral forms with lateral fruitfulness. During its migration to Western Europe, English walnut lost this character by natural selection on account of competition with other vigorous forest species such as oaks. They became big trees with terminal fruitfulness. Small remnant populations of these J. regia trees have survived the last glacial period in Southern Europe but the bulk of the wild J. regia germplasm in the Balkan Peninsula and much of Turkey was most likely introduced from eastern Turkey by commerce and settlement several thousand years ago. Four centuries BC Alexander The Great introduced in Macedonia ancestral forms with lateral fruitfulness from Iran and Central Asia. They hybridized with terminal bearing forms to give lateral bearing trees. These lateral bearers were spread in Southern Europe and Northern Africa by Romans. Recent prospections in walnut populations of the Mediterrean Basin allowed selecting interesting trees of this type. In the middle ages the lateral bearing character was introduced again in southern Turkey by merchants travelling along the Silk Road. J. regia germplasm in China is thought to have been introduced from Central Asia about 2 000 years ago and in some areas has become naturalized. Cultivated distribution now includes North and South America (Chile, Argentine), Australia, New Zealand, South Africa and Japan. So Persian walnut is grown from 30 to 50 degrees of latitude in the Northern hemisphere and from 30 to 40 degrees in the Southern hemisphere.
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Walnut Germplasm Collections at CITH
Sect. Juglans. Leaves large (20-45 cm) with 5-9 broad leaflets, hairless, margins entire. • •
Juglans regia L. (J. duclouxiana Dode, J. fallax Dode, J. orientis Dode) Persian Walnut, Carpathian, or Common Walnut Juglans sigillata Dode - Iron Walnut (doubtfully distinct from J. regia)
Sect. Rhysocaryon. Leaves large (20-50 cm) with 11-23 slender leaflets, finely pubescent, margins serrated. Wood hard. North America, South America. • • • • • • • • • • • • • • • • • •
Juglans australis Griseb. (J. boliviana Dode) - Argentine Walnut Juglans brasiliensis Dode - Brazilian Walnut Juglans californica S.Wats. - California Walnut Juglans hindsii (Jepson) R.E.Smith - Hinds’ Walnut Juglans hirsuta Manning - Nuevo Leon Walnut Juglans jamaicensis C.DC. (J. insularis Griseb.) - West Indies Walnut Juglans major (Torrey) Heller (J. arizonica Dode, J. elaeopyron Dode, J. torreyi Dode) - Arizona Walnut Juglans major var. glabrata Manning Juglans microcarpa Berlandier (J. rupestris Engelm.) - Texas Walnut or Little Walnut Juglans microcarpa var. stewartii (Johnston) Manning Juglans mollis Engelm. - Mexican Walnut Juglans neotropica Diels (J. honorei Dode) - Andean Walnut Juglans nigra L. - Black Walnut Juglans olanchana Standl. & L.O.Williams Juglans peruviana Dode - Peruvian Walnut Juglans soratensis Manning Juglans steyermarkii Manning - Guatemalan Walnut Juglans venezuelensis Manning - Venezuela Walnut
Sect. Cardiocaryon. Leaves very large (40-90 cm) with 11-19 broad leaflets, softly downy, margins serrated. Wood soft. Northeast Asia, eastern North America. •
Juglans ailantifolia Carr. (J. cordiformis Maxim., J. sieboldiana Maxim.) Japanese Walnut • Juglans cinerea L. - Butternut • Juglans mandschurica Maxim. (J. cathayensis Dode, J. formosana Hayata, J. hopeiensis Dode, J. stenocarpa Maxim.) - Chinese Walnut or Manchurian Walnut The scientific name Juglans is from the Latin jovis glans, “Jupiter’s nut”, and regia, “royal”. Its common name, Persian walnut, indicates its origins in Persia (Iran) in southwest Asia; ‘walnut’ derives from the Germanic wal- for “foreign”, recognizing that it is not a nut native to northern Europe. In Kyrgyzstan alone there are 230,700 ha of walnut-fruit forest, where J. regia is the dominant overstorey. This is the species which is widely cultivated for its delicious nuts. J. regia is also called English walnut because English merchant marines once controlled its world commerce. The Black Walnut (Juglans nigra) is a common species in its native eastern North America, and is also widely cultivated elsewhere. The nuts are edible, but have a
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smaller kernel and an extremely tough shell, and they are not widely grown for nut production. The Butternut (Juglans cinerea) is also native to eastern North America, where it is currently endangered by an introduced disease, butternut canker, caused by the fungus Sirococcus clavigignenti. Its leaves are 40-60 cm long, and the nuts oval. The Japanese Walnut (Juglans ailantifolia) is similar to Butternut, distinguished by the larger leaves up to 90 cm long, and round (not oval) nuts. Walnut Hybrids • Juglans x bixbyi Rehd. - J. ailantifolia x J. cinerea • Juglans x intermedia Carr. - J. nigra x J. regia • Juglans x notha Rehd. - J. ailantifolia x J. regia • Juglans x quadrangulata (Carr.) Rehd. - J. cinerea x J. regia • Juglans x sinensis (D. C.) Rehd. - J. mandschurica x J. regia • Juglans x paradox Burbank - J. hindsii x J. regia • Juglans x royal Burbank - J. hindsii x J. nigra
Production Scenario In India, Jammu and Kashmir leads the nation in walnut cultivation accounting major walnut production of quality nuts and earning the foreign exchange to the tune of Rs. 488 crores annually.
Major walnut producing countries in the world (Source: www.en.wikipaedia.org)
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Walnut Germplasm Collections at CITH
Area under cultivation
Production Scenario
Productivity status
Top ten apple growing, production and having highest productivity countries in world
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Promising selections made by CITH A total of 199 elite selections and cultivar of exotic and indigenous origin have been collected and established in the field gene bank of CITH. Few of the most promising election are described a below.
S. No.
1.
Salient Features
AK-2: Promising walnut genotype having extra light kernel colour suitable for export market, medium nut(13.71g/nut) & kernel (7.13g/nut) size, good kernel recovery (52%), medium shell colour round in shape, easy to removes the full kernel halves, very high nut yield (300kg/tree) from 45 year mature tree. AK-2
2.
BP-4: Promising walnut genotype having extra light kernel colour suitable for export market, bigger nut (19.31g/nut) & kernel (9.46g/ nut) size, good kernel recovery (48.99%), light shell colour ovate in shape, moderate to removes the full kernel halves, high nut yield (125kg/tree) from 55 year mature tree.
BP-4
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Walnut Germplasm Collections at CITH
S. No.
3.
4.
Salient Features
DKMW-1: Promising walnut genotype identified from Danew Kandimarg, Kulgam district of Kashmir valley. Having satisfactory kernel colour, bigger nut (20.21g/ nut) & kernel (9.71g/nut) size, good kernel recovery (48.99%), medium shell colour round in shape, easy to removes the full kernel halves, very high nut yield (300kg/tree) from 70year mature tree.
DKMW-1
FNB-1: Promising walnut genotype having satisfactory kernel colour, bigger nut (22.89g/nut) & kernel (11.54g/nut) size, good kernel recovery (50.41%), medium shell colour ovate in shape, moderate to removes the full kernel halves, very high nut yield (260kg/tree) from 55 year mature tree.
FNB-1
5.
KC-1: Promising walnut genotype having light kernel colour, medium nut (16.57g/nut) & kernel (7.19g/ nut) size, medium kernel recovery (43.39%), light shell colour elliptic in shape, easy to removes the full kernel halves, medium nut yield (120kg/tree) from 45 year mature tree.
KC-1
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S. No.
6.
Salient Features
LG-5 (IC-561050): Promising walnut genotype having light kernel colour, biggest nut (27.16g/ nut) & kernel (12.76g/nut) size among all the cultivars in the world, good kernel recovery (46.98%), light shell colour long trapezoid in shape, easy to removes the full kernel halves, medium nut yield (60kg/tree) from 30 year mature tree. LG-5 (IC-561050)
7.
LG-7(IC-561051): Promising walnut genotype having satisfactory kernel colour, bigger nut (21.75g/nut) & kernel (11.26g/nut) size, high kernel recovery (51.77%), light shell colour short trapezoid in shape, moderate to removes the full kernel halves, high nut yield (180kg/tree) from 40 year mature tree.
LG-7(IC-561051)
8.
LG-9 (IC-561049): Promising walnut genotype having satisfactory kernel colour, medium nut (13.40g/nut) & kernel (6.24g/ nut) size, medium kernel recovery (46.56%), medium shell colour round shape, moderate to removes the full kernel halves, medium nut yield (60kg/tree) from 60 year mature tree. LG-9 (IC-561049)
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Walnut Germplasm Collections at CITH
S. No.
9.
Salient Features
LG-11(IC-561053): Promising walnut genotype having light kernel colour, bigger nut (18.64g/ nut) & kernel (10.69g/nut) size, very high kernel recovery (54.34%), medium shell colour long trapezoid shape, difficult to removes the full kernel halves, high nut yield (80kg/tree) from 30 year mature tree.
LG-11(IC-561053)
10.
LG-18 : Promising walnut genotype having light kernel colour, medium nut (16.46g/nut) & kernel (7.32g/ nut) size, medium kernel recovery (44.47%), medium shell colour long trapezoid shape, difficult to removes the full kernel halves, high nut yield (90kg/tree) from 40 year mature tree.
LG-18
11.
LG-20 : Promising walnut genotype having light kernel colour, medium nut (16.70g/nut) & kernel (7.71g/ nut) size, medium kernel recovery (46.16%), medium shell colour ovate shape, easy to removes the full kernel halves, high nut yield (78kg/tree) from 28 year mature tree.
LG-20
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S. No.
12.
Salient Features
NBB-1: Promising walnut genotype having light kernel colour, bigger nut (19.76g/nut) & kernel (8.28g/nut) size, medium kernel recovery (41.90%), medium shell colour ovate shape, easy to removes the full kernel halves, very high nut yield (200kg/tree) from 58 year mature tree. NBB-1
13.
NBB-2: Promising walnut genotype having medium kernel colour, medium nut (16.86g/nut) & kernel (7.14g/nut) size, medium kernel recovery (42.34%), medium shell colour round shape, moderate to removes the full kernel halves, medium nut yield (80kg/tree) from 40 year mature tree.
NBB-2
14.
SBS-1: Promising walnut genotype having extra light kernel colour, medium nut (14.75g/nut) & kernel (7.45g/nut) size, high kernel recovery (50.50%), light shell colour ovate shape, easy to removes the full kernel halves, high nut yield (80kg/tree) from 35 year mature tree.
SBS-1
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Walnut Germplasm Collections at CITH
S. No.
15.
Salient Features
SKP-1: Promising walnut genotype having light kernel colour, medium nut (15.53g/nut) & kernel (6.85g/ nut) size, medium kernel recovery (44.10%), medium shell colour round shape, medium to removes the full kernel halves, high nut yield (160kg/tree) from 55 year mature tree. SKP-1
16.
SKP-2: Promising walnut genotype having medium kernel colour, medium nut (15.29g/nut) & kernel (6.39g/nut) size, mediu m kernel recovery (41.10%), medium shell colour narrow elliptic shape, easy to removes the full kernel halves, high nut yield (130kg/tree) from 40 year mature tree.
SKP-2
17.
SBS-2: Promising walnut genotype having extra light kernel colour, medium nut (13.69g/nut) & kernel (6.16g/nut) size, medium kernel recovery (44.99%), light shell colour broad elliptic shape, very easy to removes the full kernel halves, high nut yield (110kg/tree) from 90 year mature tree.
SBS-2
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S. No.
18.
19.
Salient Features
SKP-5: Promising walnut genotype having medium kernel colour, medium nut (15.22g/nut) & kernel (7.80g/nut) size, high kernel recovery (51.24%), medium shell colour narrow elliptic shape, difficult to removes the full kernel halves, very high nut yield (230kg/ tree) from 50 year mature tree.
SKP-5
SBS-3: Promising walnut genotype having extra light kernel colour, medium nut (16.10g/nut) & kernel (7.14g/nut) size, medium kernel recovery (44.34%), light shell colour ovate shape, easy to removes the full kernel halves, high nut yield (120kg/tree) from 50 year mature tree.
SBS-3
20.
SKP-3: Promising walnut genotype having extra light kernel colour, medium nut (13.55g/nut) & kernel (6.21g/nut) size, medium kernel recovery (45.83%), medium shell colour broad elliptic shape, moderate to removes the full kernel halves, very high nut yield (200kg/ tree) from 50 year mature tree.
SKP-3
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Walnut Germplasm Collections at CITH
S. No.
21.
Salient Features
SBS-5: Promising walnut genotype having light kernel colour, medium nut (14.21g/nut) & kernel (6.12g/ nut) size, medium kernel recovery (43.06%), light shell colour round shape, moderate to removes the full kernel halves, very high nut yield (160kg/tree) from 38 year mature tree.
SBS-5
22.
SBS-10: Promising walnut genotype having extra light kernel colour, medium nut (11.98g/nut) & kernel (5.77g/nut) size, high kernel recovery (48.16%), light shell colour oblong shape, very easy to removes the full kernel halves, very high nut yield (180kg/tree) from 40 year mature tree.
SBS-10
23.
SBS-11: Promising walnut genotype having medium kernel colour, medium nut (13.11g/nut) & kernel (5.46g/nut) size, medium kernel recovery (41.64%), medium shell colour round shape, medium to removes the full kernel halves, very high nut yield (250kg/tree) from 60 year mature tree.
SBS-11
Walnut Germplasm Collections at CITH
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S. No.
24.
Salient Features
SBS-12: Promising walnut genotype having medium kernel colour, medium nut (16.16g/nut) & kernel (8.14g/nut) size, high kernel recovery (50.37%), light shell colour ovate shape, easy to removes the full kernel halves, very high nut yield (190kg/tree) from 45 year mature tree.
SBS-12
25.
SPB-1: Promising walnut genotype having light kernel colour, medium nut (15.11g/nut) & kernel (6.68g/ nut) size, medium kernel recovery (44.20%), medium shell colour round shape, easy to removes the full kernel halves, high nut yield (80kg/tree) from 35 year mature tree. SPB-1
26.
BBW-8: Promising walnut genotype having light kernel colour, medium nut (14.78g/nut) & kernel (8.63g/ nut) size, very high kernel recovery (58.38%), light shell colour round shape, very easy to removes the full kernel halves, high nut yield (70kg/ tree) from 35 year mature tree. BBW-8
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Walnut Germplasm Collections at CITH
S. No.
27.
Salient Features
LFA-4: Promising walnut genotype having light kernel colour, medium nut (10.01g/nut) & kernel (4.83g/ nut) size, high kernel recovery (48.25%), medium shell colour broad elliptic shape, easy to removes the full kernel halves, high nut yield (10kg/tree) from 10 year mature tree.
LFA-4
28.
TVB-1: Promising walnut genotype having light kernel colour, medium nut (13.28g/nut) & kernel (6.75g/ nut) size, high kernel recovery (50.83%), medium shell colour long trapezoid shape, easy to removes the full kernel halves, medium nut yield (45kg/tree) from 25year mature tree.
TVB-1
29.
LFA-1: Promising walnut genotype having light kernel colour, medium nut (8.60g/nut) & kernel (4.50g/ nut) size, very high kernel recovery (52.39%), medium shell colour ovate shape, easy to removes the full kernel halves, high nut yield (10kg/tree) from 10year mature tree. LFA-1
Walnut Germplasm Collections at CITH
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S. No.
30.
Salient Features
YKB-4: Promising walnut genotype having light kernel colour, medium nut (13.73g/nut) & kernel (7.51g/nut) size, very high kernel recovery (54.70%), medium shell colour elliptic shape, easy to removes the full kernel halves, very high nut yield (140kg/tree) from 50 year mature tree.
YKB-4
31.
YKB-3: Promising walnut genotype having light kernel colour, medium nut (9.76g/nut) & kernel (6.12g/nut) size, very high kernel recovery (62.72%), medium shell colour round shape, easy to removes the full kernel halves, very high nut yield (150kg/tree) from 80year mature tree.
YKB-3
Exotic Walnut Cultivars A quite number of commercial cultivar of walnut are commonly grown in the countries like USA, France, Spain etc having good qualitative traits. Out of which only few number of exotic cultivar like Opex Culchery, Tutle, Nugget, and Chenovo has been introduced and planted in the field gene bank of CITH to see their comparative performance. The salient features of the promising exotic walnut cultivars as under. ASHLEY - from the breeding program of the Pomology Department University of California at Davis, 90% of lateral buds produce female (‘pistillate’) flowers, and
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Walnut Germplasm Collections at CITH
therefore, potentially, nuts. Ashley matures it’s nuts relatively early because it comes into leaf early. For this reason, it is not suitable for areas with heavy spring frosts. Like many early leafing Californian selections, it is extremely sensitive to being infected with walnut blight (Xanthomonas juglandii) if it is rainy in spring and therefore not so suitable for humid areas. The kernel weight averages 5.3 grams, and the recovery averages 50%. CHANDLER - also from the University of California at Davis, this is one of the most important commercial nuts. Chandler crops heavily, as it bears on laterals (80% of lateral buds are female) as well as terminals. Chandler is self fertile. The harvest is in the middle of the walnut season. The tree is a standard large walnut tree, growing to around 12 metres/40 feet, moderate vigor, and somewhat upright growing (rather than spreading). 700 hours winter chilling needed, and Chandler is late leafing, leafing out about 3 weeks after the early leafing varieties such as Payne, Serr, Ashley, Sunland, Chico and Vina It is not as susceptible to walnut blight as most other Californian varieties. The nuts are large (kernel weight 6.3 grams, crackout 49%), smooth, well sealed, and almost all kernels have a light colored skin. Pollenized by Cisco and Franquette. CHICO - many desirable features for the home gardener- upright, small, 90% lateral bud potentially nut bearing (makes it possible to prune without losing the crop), and it is one of the heaviest bearing varieties available. The nuts mature early in the season. Like many early leafing Californian selections, it is extremely sensitive to being infected with walnut blight if it is rainy in spring, and therefore not so suitable for humid areas. Chico comes into leaf early, so is also not suitable for areas with heavy spring frosts. The nuts are small (kernels average 5 grams, and the crackout is 47%), but the quality of the kernels is good. Pollenized by Payne, Serr, Vina and Sunland. CISCO - highly desirable from the point of view it is both a small tree and upright, not spreading. The nuts are large, but, at least from the commercial standpoint, kernel quality is not optimal. Of the californian walnut blight suceptible group, Chico is affected, but less badly affected. Cisco also pollenizes another relatively small cultivar, ‘Howard’ as well as ‘Chandler’. DANIELS - The tree bears heavily, the nut is thin shelled, medium sized, and cracks out at about 40% kernel. EUREKA - a very large and spreading tree, and a 100% terminal bearer, so not really suited to the home garden situation. FRANQUETTE - a late leafing old French variety, so it is good for areas with late spring frosts. Unfortunately, it is also late flowering which means it misses the pollen shed by other varieties, so nut set and yields are often poor. It may be worth trying ‘Mayrick’, also late flowering, as a pollenizer, or ‘Rex’. Most Californian varieties are susceptible to walnut blight, and are therefore poorly suited to wet and humid areas, but Franquette seems to have some degree of blight resistance. On the downside, from the home garden viewpoint, the tree is vigorous and spreading, slow to come into bearing, and Franquette is also a 100% terminal bearer. The nuts are large, and
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attractive. Kernel weight averages 5.2 grams, and crackout is about 46%, altho’ it may be lower in some conditions. Franquette reputedly also has very high quality timber. HARTLEY - a medium to large tree, It leafs out mid to late season and requires a fertile soil for optimal growth. Requires a late blooming pollenizer, such as ‘Amigo’ or ‘Franquette’. Almost all nuts are from terminal buds. In cooler and shorter growing season areas it may not have a long enough growing season for good production. Production is overall usually fairly good. Of the Californian walnut blight susceptible group, Hartley is affected, but less badly affected than the others. Hartley has a well sealed, large nut with a light colored kernel. Kernel weight is 5.9 grams, and recovery 45%. HOWARD - a relatively new Californian cultivar, this tree is upright and small to medium sized, only moderately vigorous, which makes it particularly well suited to home gardens. In addition, it bears on laterals (approximately 80% of lateral buds are female). Howard leafs out midseason, and is not as susceptible to walnut blight as most other Californian varieties. Howards yield is regarded as very good. The large smooth nuts have a 50% recovery, are well sealed, and the kernel (weight 6.0 grams) is light colored. Pollenized by Franquette, Cisco, and possibly Tehama. DUBLIN’S GLORY- released in 1997. Selected from Carpathanian stock for its winter cold tolerance, but flowers early in spring, so it is not suitable for areas subject to late frosts. About 42% recovery. Nuts mature early, drop clean of the husk, and pretty much all drop about the same time. MEYRICK (W/H/1199-4) - released in 1997. Selected for areas subject to late frosts. Late leafing and late flowering, early to go dormant. The tree is not as vigorous as Californian cultivars. A large (29 x 40mm), elongated rather than round, thin shelled nut, with very good kernel quality (plump, pale, even halves that are easy to extract, mild taste). It also has the virtual of being blight resistant. Recovery is around 47-53%, and the kernel weight is about 6 grams. PAYNE - a medium sized tree that can be pruned, as it is a lateral bearer (about 80% of flowers are from lateral buds). It is quite an old variety, and noted for it’s good productivity, although the nuts are only medium to small. Payne is relatively early to mature it’s nuts because it is an early leafer. Payne is not suitable for areas with heavy spring frosts for this reason. It is also unsuited to humid areas because it is very susceptible to walnut blight (Xanthomonas juglandii) The seal between the two halves of the nut is good. Kernel weight averages 5.2 grams, and recovery is 48%. PEDRO - a particularly desirable walnut for the home gardener because it is a relatively ‘small’ tree at about 9 metres/30 feet, it is self fertile, it only needs 400 hours of winter chill (not suited to areas with late frost), and the nut is both well sealed and particularly liked when tested in consumer taste panels. On the ‘down’ side, its productivity is regarded as only ‘fair’. Kernel weight is 6.5 grams, and recovery is 48%. REX - (C 152) released in 1997. Selected for areas subject to late frosts. Late leafing and late flowering. Vigorous and very productive, the nuts are small, round and light
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Walnut Germplasm Collections at CITH
colored. The kernel is pale, smooth, sweet, mild, and pleasant. Recovery is about 45%. It is high in 18:3 polyunsaturated fatty acids, but low in vitamin E relative to other cultivars. SAUBER 1 - Anthracnose resistant, heavy and reliable producer, large nut, 35% recovery. SERR - A Californian cultivar released in the late 60’s, Serr is very vigorous and large, and needs to be lightly pruned every year. Serr bears large, well filled, thin but strong shelled nuts on laterals as well as tips (nut bearing is evenly distributed between terminal and lateral buds). Its usual crop load is rated as ‘fair’. It is an early leafing variety, so it is unsuitable for areas with late spring frosts. Unlike most early leafing Californian cultivars it has some resistance to bacterial blight infection. On very fertile, well drained soils it tends to be an excessively strong grower and difficult to control. Serr comes into bearing quickly once planted out. Variable 50- 58% recovery, average kernel weight 6 gms, larger nuts the kernel weighs 7.6 grams. Pollenized by Chico, and Tehama. SPARROW- A partially self fertile tree producing heavy crops of medium sized, nice flavoured, well filled nuts. STAN - (BLE 300) released in 1997. Selected for areas subject to late frosts. Late leafing and late flowering. Not as vigorous as the Californian varieties, although’ ultimately a large tree, slower to start producing, and a variable cropper - at least under Canterbury (NZ) conditions . The elongated nuts are small to medium sized, with a smooth nice colored shell, and the kernel quality is particularly good, being light colored and mild tasting - although’ it can’t be described as plump. Recovery is about 46%. SUNLAND - An early leafing Californian cultivar carrying good crops of large nuts. Like many early leafing Californian selections, it is extremely sensitive to being infected with walnut blight if it is rainy in spring, and therefore not so suitable for humid areas. A good lateral bearer, 80% of lateral buds bear female flowers. Sunland has particularly big nuts, with kernels weighing 9.9 grams. Recovery is very good, at 58%. The nuts mature late. TEHAMA - A late leafing Californian cultivar that, although’ a lateral bearer (80% of lateral buds are female), and particularly easy to crack, has the disadvantage that the tree grows very big and its productivity is rather poor. It is perhaps best suited to ‘country living’ situations, rather than suburbia. Even although it is late season leafing Tehama is extremely sensitive to being infected with walnut blight if it is rainy in spring. It is therefore not so suitable for humid areas. Kernel weight is 6.7 grams, and recovery is 50%. THOMAS MYERS (Hayes) - large thin shelled nuts, late leafing out, anthracnose resistant, , 38% recovery. TULARE - (Serr x Tehama) a newly developed Californian walnut, upright and moderately vigorous, Tulare has the advantage of being self fertile. It blooms late, an advantage in frosty areas, but is still matures its nuts mid season. It has around 70%
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lateral buds. First indications suggest it may come into bearing early and bear relatively heavily when young. The nuts are large, rather round, and well sealed. The recovery is around 53%. (Patented, limited distribution) VINA - A Californian cultivar, slow to establish, Vina bears high quality, medium sized, well sealed nuts on laterals as well as tips, and is therefore a heavy cropper, as well as being a regular cropper. The tree itself is small to medium sized, and pruneable. It and is well adapted to areas with high summer temperatures. Like many early leafing Californian selections, it is extremely sensitive to being infected with walnut blight if it is rainy in spring. Best pollenizer is Chico, or Chandler, Howard, or Tehama. In Canterbury (NZ) conditions the nut has been pointed and thin. Consequently the sometimes rather dark kernel is long and flat. Kernel weight averages 5.6 grams, and recovery is about 48%. W/AH/1335 - A New Zealand cultivar selected for blight resistance and good recovery (50%). WIGG - A large nut, somewhat similar to Wilson’s Wonder. The recovery is %37, and the kernels are large, at about 8 grams. WILSONS WONDER - the nuts are very large, but the percentage recovery is not high (30-40%). Nevertheless, altho the large nuts are not exceptionally well filled, the kernels are still large - around 6-8 grams. The nuts don’t always seal well, and the kernels can be affected by blight in wet and humid areas. Black walnut ( Juglans nigra): It is a species that grows in the East of North America and whose hard nuts have constituted a good food source for the indigenous tribes. It is characterized by its big leaves that can reach till 60 cm long. Its wood is the hardest, reason why it is much used in buildings, besides in the production of furniture or ships. Japanese walnut (Juglans ailanthifolia) : With less height than the previous one, it simply attains 18 meters high, although its leaves are longer, being able to extend till 80 cm long . Native to Japan, it highlights for its nuts that are very flavorful and end up in prolonged tip in one of the ends. Its bark has been used in the dyeing industry. White walnut, butternut ( Juglans cinerea): Coming from the East of North America, it stands out for its nuts covered with hair and for its leaves covered with starry hairiness at the back. Its bark has also been used in the dyeing industry.
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Walnut Germplasm Collections at CITH
WALNUT COLOR CHART (For classifying walnut kernels in connection with the United States Standards for Grades of Shelled Walnuts and the United States Standards for Grades of Walnuts in the Shell)
DARKEST COLOR PERMITTED IN “EXTRA LIGHT” CLASSIFICATION
DARKEST COLOR PERMITED IN “LIGHT” CLASSIFICATION
DARKEST COLOR PERMITED IN “LIGHT AMBER” CLASSIFICATION
DARKEST COLOR PERMITED IN “AMBER” CLASSIFICATION Source: USDA, California, USA
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Walnut Germplasm Collections at CITH