leguminous vegetable cultivation

Leguminous Vegetable Cultivation and Seed Production

S. Shanmugasundaram

Introduction

Leguminous vegetables have been cultivated for more than 6,000 years in different parts ofthe world. Legumes for human consumption constitute about 5% of the cultivated crops. Worldproduction of selected vegetable legumes are given in table 1.

ions and the worldProduction (t x 1000)

4,699144

2,527636

11,36122

14,6371,082

96,00010,000

In countries like India where majority of the population are vegetarians, leguminousvegetables serve as the major source of protein in the diet. In developing third world countries,especially for the' poor, the major protein source in the diet are vegetable legumes. Mostleguminous vegetables are rich in phosphorus, calcium, iron, and a number of essential vitamins;crops like soybean, groundnut, and Bamabara groundnut are also rich in fats which are needed bythe body to absorb vitamin A. Although leguminous vegetables are deficient in some of the sulfur-containing aminoacids, they are well compensated when consumed with cereals. In some instancesthe leaves, tender shoots, and roots are harvested and used as vegetables. The whole seed of someof the legumes are called grain. Seeds of legumes without seed coat and cotyledons split into halfare commonly called as pulses in India. Similarly the split pigeon pea, Cicer arietinuin, L. isreferred to as dal in India and Pakistan. According to Vavilov all the main centers of origin ofcultivated plants have contributed to the cultivated legumes of today.

Legumes are rather unique compared to other vegetables in that they can obtain freeatmospheric nitrogen through their symbiotic association with the nitrogen-fixing bacteria,Rhizobiwn or Pradyrhizobium, in legume root nodules. The nitrogen fixed in the root nodules arenot only available to the plant but they also enrich the soil, in varying amounts, when the plantscomplete their life cycle.

Many leguminous vegetable plants contain toxic substances like trypsin inhibitor{ (soybean, Glycine max (L.) Merrill)], rotenone (yam bean, Pachyrhizus erosus L.), andcyanogenic glucoside (hyacinth bean, Lab lab niger L., and Lathyrus sativus L.). There are diverseways by which the toxic effects of these vegetables can be eliminated rendering them safe forhuman consumption.

Table 1. Area andVe etableGreen peas

Green beans

Dry peas

Dry beans

Soybeans

Countr / RegionWorldAsiaWorldAsiaWorldSoutheast AsiaWorldSoutheast AsiaWorldAsia

Area (ha x 1000)802

89391102

8,42827

25,9591,437

52,6007,500

roduction of selected ve getable le

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Depending upon the country some of the legumes are included in the field crops category,others are included under horticultural crops, while still others are included in the oilseeds cropgroup. However, in many of the monographs dealing with vegetable legumes published indifferent countries almost all these crops are treated as vegetable crops.

Leguminous vegetables are used as fresh pod, immature seed and mature dry seed, and majority ofthese vegetables are also canned and frozen for the market. Some of the legume seeds are sproutedand are popular in many Asian countries. any legumes are also processed.

In international trade leguminous vegetables play an important role. Dry seeds, canned andfrozen foods, and processed food products from leguminous vegetables enter the internationalmarket where they are important commodities for foreign exchange.

Botany

Legumes are dicotyledonous annuals or perennials. There are about 480 genera and morethan 12,000 species in the family Leguminosae (commonly called the pea family). As a group theycontain at least 28 different vegetable crops belonging to 18 genera. Almost all the vegetable cropsbelong to the subfamily Papilionaceae.

When the seeds germinate, in some legumes, the cotyledons remain inside the soil due tolimited elongation of the hypocotyl. Such germination is referred to as hypogeal germination.Example: peas, Pisum sativuin L. In other instances, as in the case of soybean (Glycine max L.(Merr.) and common bean (Phaseolus vulgaris L.) the cotyledons are pushed above the soil surfaceby the rapid elongation and growth of the hypocotyl. Such germination is called epigealgermination.

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table. 2A list of leguminous vegetables commonly grown in South and Southeast Asia are given in

Table 2. Leguminous vegetables gown in SCrop Botanical name

outh and Southeast Asia.l iromosome Edible part

no.Adaptation

BeansCommon, Snap, Phaseolus vulgaris L. 22 Immature pod, mature seeds Temp. and tropics

StringLima bean P. lunatus L. 22 Green seeds Warm seasonTepary bean P. acutifolius A. Gray 22 Dry beans Dry areasAdzuki bean Vigna angularis (Wind) Ohwi & 22 Immature pod, mature seeds Warm season

Mungbean, greengram

Ohashi

V. radiata (L.) Wilczek 22 Green pod, mature seeds, Warm season

Blackgram, Urd bean V. mungo (L.) Flepper 22

sprouts

Mature dry seeds Warm season, dry tropicsRice bean V. umbellate (Thunb) Ohwi and 22 Mature dry Warm season

Peas

Ohasi

Pist nn sativunl L. 14 Immature, seeds, pods, tender Cool, humid season

Peanut, Groundnut Arachis hypogaea L. 40

leaves

Mature seed, tender shoots, and Tropics and subtropics,

Swordbean Canavalia gladiata (Jacq.) D.C. 22,

leaves

Young pods and beanswarm temp.

Tropics44,46

Pigeon pea, redgram Cajanus cajan L. Millsp. 22 Young green pods, seeds, Warm season

Chickpea, Cicer arietinum L. 16mature seeds

Green pods, tender shoots, dried Cool, dryBengalgram

Clusterbean, guar Cyamopsis tetragoraoloba (L.) 14

seeds

Young tender pods Dry tropics

Soybean

Taub.

Glycine max (L.) Merr. 40 Immature green seed; mature dry Tropics to 52°N

Hyacinth bean, lablab Lab lab purpureus (L.) 22seed, sprouts

Young pods, tender bean, dried Dry seasonbean

Grass pea, Chickling Lathyrus sativus L. 14

seeds

Seeds, leaves used as herbs Cool seasonpea

Lentil Lens culin..aris Medikus 14 Mature seed Winter cropYam bean Pachyrhizus erosus Urban 22 Succulent roots Hot, wet tropics,

Potato bean P. tuberosus spreng 22 Tubersperennial

PerennialWinged bean Psophocarpus tetragonolobus 18 Almost all parts used Tropical Asia

FenugreekD.C.

Trigonella foenum-graecum L. 7 Mature seeds WinterFaba bean, broad Vicia faba L. 12 Green beans, dry seeds Temp. cool season

bean, Horse bean,Windsor bean

Cowpea, Catjang Vigna unguiculata (L.) Walp 22 Immature pods, young shoots, Trop. Africa

Yardlong bean, V. sesquipedalis (L.) Walp 22dry beans

Immature pods Warm seasonAsparagus bean

Bambara groundnut Vigna subterranea (L.) Walp 22 Immature and mature seeds Tropical AfricaHorsegram Macrotylom.a unifloruin (Lam) 20, Mature seeds Dry tropics

Verde 22Runner bean Phaseolus coccineus L. 22 Green pods TemperateMoth bean Vigna aconitifolia (Jacq.) 22 Green pods, dry whole or split Tropical

Marechal seeds

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Description of Selected Legumes

L Snap, String, or French Bean

Phaseolus vidgaris likely originated from Central America. It is commonly associated withcorn and squash culture in the tropical Latin American countries. It is an annual with epigealgermination.

CIAT in Cali, Colombia has classified the world collection of this bean into the followingfour main types by growth habit: (1) dwarf determinate, (2) dwarf indeterminate, (3) prostrateindeterminate, and (4) climbing indeterminate. Beans are also classified according to use asfollows: snap or string beans (for tender fresh pods); green shell beans (green shelled condition,normally bush and climbing varieties); and dry-shell or field beans (mature dry seeds);

a_lLus

Peas probably originated in Southwest Asia. It is a cool season crop in the subtropics andalso grown at higher altitudes in the tropics.

2, Mungbean

India or the Indo-Burmese region is the origin of mungbean. In South Asia it is one of themajor leguminous vegetable crops. In Southeast Asia it is one of the three main legumes.

4. Vegetable Soybean (Fdamame)

Soybean originated as a domesticate in the eastern half of northern China around the 11thcentury BC. It was introduced from China to the USA, Japan, Korea, and South and SoutheastAsian countries at different times.

Large yellow or green-seeded varieties with gray hilum are preferred for use as vegetablesoybeans. Based on latitudinal adaptation soybean cultivars in the USA and Canada have beenclassified into 13 maturity groups (MG). MG 000, 00, and 0 are early and adapted to extremenorth latitudes while MG IX and X are late and adapted to tropical latitudes. However, this MGsystem breaks down in the tropical and subtropical latitudes.

Controlled Hybridization Procedures

1. Mun. bean

India has done considerable research on mungbean through their "Pulse Scheme" since1943. In 1967 an All-India coordinated Pulse Improvement Program commenced with yield anddisease resistance as the primary concerns. A number of varieties have been released (table 3).

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Table ri beLan cultivars released in IndiaCtdtivar name Source/ parents Year Location Ref.2

MaturityImprove&

(days) characters"T-ileysiap.0 as selections

1948 U.P. 60 G, GM 1Type 1 MuzaffarpurShining Mung No. 1 Kuhl bung Type 1 Punjab 65 LG, S 2COI Local 1952 Tamilnadu 135 SG, DL 3CO2 PLS 365/3 1975 Tamilnadu 65 DG 4CO3 PLS 367 1976 Tamilnadu 70 SG, IRC 4BR-2 Bhagalpur Local Bihar 110-115 MG 5Arndt Bihar Local Bihar 9 0 MY, YMV 5Khargone-1 K 119-56 M.P. 65 LG, GM 5_R-288-8 Local Rajasthan 70-75 SG 5Krishna-11 Gwalior Local M.P. 65 LG, GM 5D66-26 Local 1968 Rajasthan 60-65 SG 5Musa-Baisakhi Type 44 New Delhi 60-65 DG, spring 5

1975 Maharashtra 60and summerSG 6Kopergaon Local

Developed b bridization and selectionType 44 Type 1 x Type 49 1948 U.P. 60-65 DG, summer, 7

1962 U.P. 75-80

spring

SG, mixed 8Type 51 4465-4 x Type 49

Jawahar-45 Madira x UP local 1972 M.P. 75-80cropSG, kharif 9

S-8 (Mohini) BR 2 x T2 1972 New Delhi 60-65 SG 10Kanke Multipurpose Tl x China Moong 1973 SG 11

781ML 1 Hyb. 45 x 23-67 1973 Punjab 9 0 G, tolerant to 12

KM I S 8 x PS 16 1978 Tamilnadu 65

disease

YMV, pod 5

NM 5 No. 54 x Hyb. 45 Punjab 80-85

borer

G, kharif 5PS 7 1981 New Delhi 60-65 DG, Summer 5PS 10 1981 New Delhi 60-65 DG, Summer 5

G = green seed; GM = for green manure; LG = light green seed; SG = shiny green seed; S =shiny seed; DO = dull seed; DL = dry land; IRC = irrigated conditions; MG = mottled greenseed; MY = mottled yellow; YMV = yellow mosaic virus-tolerant.

2 1 - S.P. Singh 1955; 2 - S.G. Singh 1965; 3 - Premsekar and Srinivasan 1961; 4 -Rathnaswamy et al. 1977; 5 - D.P. Singh 1982; 6 - Mandoli and Nigam 1966; 7 - Pathak andSingh 1961; 8 - Pathak et al. 1962; 9 - L. Singh et al. 1972; 10 - S.P. Singh 1972; 11 -

'Bhargava 1973; 12 - S. Singh et al. 1973.

In the Philippines syncrhronized maturity, seasonal adaptation, and high yield along withdisease resistance were emphasized. The Bureau of Plant Industry and the University of thePhilippines Los Banos conduct research and develop new varieties.

Indonesia, Thailand, USA, Sri Lanka, and Australia have mungbean breeding programswhich have released new improved varieties that are high yielding, carry resistance to powderymildew and cercospora leaf spot, have synchronized maturity, and large seed size. A list ofvarieties from AVRDC materials released in different countries are given in table 4.

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Table 4. AVRDC mun bean selections released as cultivars in different countriesCultivar AVRDC no. Year of Country

releaseImproved characters'

ASVEG VC 1089-A 1978 Costa Rica HYB angasa V 3476 1980 Korea HY, UM, LRTainan Sel. #3 VC 1628A 1981 Taiwan HY, UM, LRM 986 VC 156OD2 1981 India2

1982 AustraliaKing V 13882 1982 Australia HY, EM, PW, LRStation 46 VC 1000-45-B 1982 Fiji HYSeonhwa Nogdu VC 1973-A 1982 Korea HY, MMV, RPM, (CLS), UMType 77 VC 1131-B-12-2B 1982 Sri Lanka HY, MYMV, CRManyar VC 1089-A 1983 Indonesia HY, CLS, RNuri V 2773 1983 Indonesia HY, (CLS), R

1983 Malaysia3

Imara V 1380 1983 TanzaniaStation 25 VC 1007-14-1-5B 3 1984 FijiStation 27 VC 1160-1-1-2B 3 1983 FijiBPI Mg2 VC 1163 1984 Philippines HY, CLS, RPM, RXu Yin No. 1 VC 1973-A 1985 China HY, WABoliche 451 VC 1163 3 1985 EcuadorKPS No. 1 VC 1973-A 1985 ThailandKPS No. 2 VC 2778-A 1985 ThailandWalet VC 1163-A 1986 Indonesia HY, NS< CLS, 'RPM, TDO, UMGelatik VC 1160-22B-1-B 1986 Indonesia HY, NS< CLS, RPM, UMBPI Mg4 VC 2764-B 1986 Philippines HY, UM, LR, EM, (CLS), RPMDX 102a VC 2768-A 1986 Vietnam HY, SLS-R, RLDDX 113 VC 2763-A 1986 Vietnam NY, TASS, RLD

HY = high-yielding; UM uniforrn maturing; LR = lodging-resistant; EM = early maturing; PW= resistant to pod weathering; CLS/(CLS) = resistant/moderately resistant to cercospora leafspot; RLD = resistant to local diseases; SLS-R; Sandy loam soil after rice; TDO = tolerant todamping off; R = rust-resistant; MMV = resistant to mungbean mottle virus; RPM = resistant topowdery mildew; MYMV = resistant to mungbean yellow mosaic virus; CR = resistant tocharcoal rot; WA = wide adaptability; TASS = tolerant to acidic and saline soils; NS =nonshattering.Adapted selection developed from AVRDC parental stocks.Reported released but no further information.

Through intensive research efforts at AVRDC in collaboration with national programscientists the yield potential of mungbean has been improved from 0.5 t/ha to more than 2 t/ha.Photoperiod insensitivity, multiple disease resistance, large seed size, and synchronized maturityhave been incorporated in improved lines.

2„Vegetable Soybean

The most popular vegetable soybeans in Japan are predominantly developed by private seedcompanies. Among 50 new vegetable soybeans, the most popular ones are: Tzuzunoko, Ryokkoh,Kegon, Hatsutaka, Taisho Shiroge, Nakate Maori, Suzumo, Enrei, Fukuda, Raityo, Shirobato,Tamasudare, Hakutyo, Shiratsuyu, and Blue Side.

In Taiwan at present the leading varieties are Kaohsiung No. 1., Tzuzunoko, andRyokkoh. Kaohsiung No. 1 (KS #1) is a pureline selection from Taisho Shiroge from Japan doneat AVRDC. Detailed trials and final assessment for release were done by Kaohsiung District

1

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Agricultural Improvement Station (DAIS). KS #1 was released in 1987. In 1988 it occupied 51%of the total vegetable soybean area in Taiwan. In 1989, it occupied more than 80% of the area.

References

Fehr, W.R. and H.H. Hadley. 1980. Hybridization in crop plants. American Society ofAgronomy. Madison, Wisconsin, USA 765 p.

Gritton, E.T. 1986. Pea Breeding. In: P. 283-319. M.J. Bassett (ed.). Breeding Vegetable Crops.AVI Publishing Co. Westport, Connecticut, USA.

orton, F., R.E. Smith and J.M. PoehIman. 1982. The Mungbean. University of Puerto Rico,Mayaguez. 136 p.

Pandita, M.L., and P.S. Pratap. 1986. Peas and Beans. In: P. 469-496. T.K. Bose and M.G.Som (ed.). Vegetable Crops in India. Maya Prokash, Calcutta-Six.

Parthesarathy, V.A. 1986. French bean. In: P. 497-514. T.K. Bose and M.G. Som. (ed.).Vegetable Crops in India, Nayo Prokash, Calcutta-Six.

Shanmugasundaram, S. 1988. A catalog of mungbean cultivars released around the world.AVRDC, Shanhua, Tainan. 20 p.

Shanmugasundaram, S. and B.T. McLean. '1988. Mungbean: Proceedings of the SecondInternational Symposium. AVRDC, Shanhua, Tainan. 730 p.

Shanmugasundaram, S., S.C.S. Tsou, and S.H. Cheng. 1989. Vegetable soybeans in the East.In: P. 1979-1986. A.J. Pascale (ed.). World Soybean Research Conference IV.

Shanmugasundaram, S., and J.M. Poehlrnan. 1989. Genetics and breeding of Mungbean. In:A.K. Mandal (ed.). Genetics and Cytogenetics of Crop Plants.

Sibernagel, M.J. 1986. Snap bean breeding. In: P. 243-282. M.J. Bassett (ed.) BreedingVegetable Crops. AVI Publishing Co. Westport, Connecticut, USA.

Van der Maesen, L.J.G. and S. Somoatmadja. 1989. Plant Resources of South-East Asia. PudocWageningen. 105 p.

Yamaguchi, Mas 1983. World Vegetable. AVI Publishing Co. Westport, Connecticut, 414 p.

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No-Tillage Rice Stubble Soybean Cultivation (NTRSC)

Many farmers in southern Taiwan have been growing soybean after harvesting rice,without tilling the land. After producing two rice crops, the farmers are able to grow a third crop ofsoybean in the same field. They use minimum resources and earn a reasonable income. Thispractice can be easily adopted in other tropical countries where rice-based cropping systemspredominate.

The no-tillage approach for growing soybean after rice with limited resources produce ahigh-value soybean crop with low inputs within a short growing season.

Soybean cultivation practiced by farmers in southern Taiwan is presented in the following:

• The no-tillage rice stubble soybean cultivation or N-T-R-S-C can be practiced in a rice-basedcropping system wherever rice is a major crop.

• The farmers in southern Taiwan grow two rice crops from January to September and a third cropof short duration early maturing soybean from September to December just after harvesting ricewithout land tillage.

• After the rice crop is harvested and threshed, the rice straw is bundled and kept in the rows.

e The rice stubbles left after the harvest serve as markers of planting rows for soybean.

• To plant soybean, either a planter is used or a group of men and women are employed forplanting. A bag containing soybean seed is worn around the waist and each person plants about 5rows at a time. Each individtial plants about 1,000 M2 in one day.

e With the help of a small trowel, a shallow hole (3 to 4 centimeters deep) is made near each ricestubble and 3-4 seeds are dropped in each hole. The hole is not covered.

• The spacing between and within the row is the same as that for rice, either 22.5 cm by 22.5 cmor 25 cm by 25 cm.

• Just after planting, a herbicide mixture of alachior at the rate of 1.5-2 kilograms active ingredient(al.) per hectare plus paraquat 0.75 kg a.i./ha is applied to control weeds.

• The rice straw is then spread on the field. The straw should not be allowed to hang on to thestubble to prevent shading which could result in lanky and weak seedlings.

•A paddy row marker is used as a roller to press the rice straw close to the ground. The rice strawmulch conserves moisture and suppresses weed growth.

• In some low-lying areas, the straw is burnt after spreading. Burning of the straw reduces excessmoisture, destroys the weeds, kills some insect pests and their eggs and adds potash to the soil.

e Reduction of soil moisture loosens the soil making it friable, and providing optimum conditionsfor seed germination.

• The seedlings emerge easily from the straw mulch.

•A fertilizer mixture containing 20 to 30 kg N + 60 kg P205 + 80 kg K20/ha is prepared andbroadcasted on the mulched field. Or, it may be applied just after burning the straw. In the burntfield, the quantity of potash is reduced to 50-60 kg/ha.

• You can see the excellent germination in fields with rice straw mulch or on a burnt field.

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At the seedling stage, the crop is usually attacked by beanflies. The adult beanfly may be foundon the leaf. The beanfly larva or maggot tunnels through the stem and causes the most seriousdamage.

To control beanfly, spraying of insecticides such as monocrotophos or omethoate or dimethoateat the rate of 0.25-0.5 kg a.i./ha 3-4 days after emergence of seedlings is suggested. The spray isrepeated 3 to 4 times or more at weekly intervals depending on insect infestation.

Soybean is attacked by rust disease which may cause serious yield losses. Plant rust-tolerant/resistant cultivars, if available. Fungicides such as mancozeb or triadimefon at 2 kga.i./ha can be sprayed against soybean rust. Spray 2 to 3 times as needed. To reduce the cost ofspraying, the fungicide and a compatible insecticide can be mixed and sprayed. If labor isavailable, the field may be hand weeded occasionally.

Three to four seeds planted per hole gives a density of about 500,000 to 600,000 plants perhectare which covers the field very well and also controls weed growth. The crop matures inabout 85 to 100 days. Harvesting is generally done manually.

• The beans are threshed with a locally developed mechanical thresher. Threshed seeds are cleanedand dried in the sun and marketed.

• The yield of an 85 to 100-day soybean crop is between 1.4 and 3 tons per hectare.

Mungbean Sprout Productioq

Mungbean is an important legume crop extensively cultivated in many developing countrieswhere a variety of mungbean dishes and other products are prepared. The mungbean sprout is atraditional vegetable in China and Southeast Asia. However, mungbean sprout is not well knownin South Asia, Africa and most other mungbean-producing countries where a vast potential for itscommercial production, consumption and export exists.

Mungbean sprout production is a simple germination process which requires neithersunlight nor soil; it has no seasonal limitations. The process is completed in just four to eight days.The sprout production is extremely inexpensive, requiring only mungbean seeds, sproutingcontainers and water as inputs. It can, therefore, be practiced even by poor farmers in augmentingtheir meager resources. Mungbean sprouts serve as a good alternative vegetable and source ofincome. This is especially true during hot wet summer and rainy seasons when there is acuteshortage of fresh vegetables, or in the event of crop losses due to natural calamities like typhoon,flood or epidemics of diseases or insect pests.

The potentials of mungbean sprout as a cheap nutritious food and the method of producingmungbean sprout for domestic use as well as for earning an income are described below:

• Mungbean sprouts cooked alone or mixed with meat or other vegetables provide a fresh andnaturally nutritious dish.

Mungbean sprout production simply involves germination, which can be done indoorsthroughout the year. It does not require soil and sunlight.

• The procedure involved in sprout production includes washing, soaking, sprouting, harvestingand packing.

e Small hard-seeded mungbean often has poor germination and weak sprout growth. Large-seededmungbean is also not so economical since they result in lesser sprouts.

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• Choose good quality, premium grade mungbean seeds of medium size with smooth seed coats.Remove broken and shriveled seeds. Be sure that beans are not treated with fungicidesor insecticides.

• Store seeds under cool and dry conditions to ensure high seed germination and sprout vigor.Beans stored under WC and 85% relative humidity produce good quality sprouts. Seeds with15% moisture can be safely stored for one year at 10 0C or below.

• Before soaking, wash the seeds in fresh water, stirring vigorously three to four times to allowthe empty, broken and light seeds to float. Remove the floating seeds and debris. Repeatwashing using fresh water every time until the beans are thoroughly cleaned.

. In Taiwan, traditional earthen wares and stone jars are used for sprouting mungbean seeds.These containers have holes near the bottom to drain out excess water.

• For larger quantity of seeds, use germination tanks of convenient size, preferably lined with tiles.Wash containers thoroughly with hot water (80 0C) before use. Big plastic containers will also do

• Arrange and perform all sprouting operations in a sheltered place to protect the sprouts fromlight. Darkness ensures bright white and long mungbean sprouts. Moderate temperature (23-28 0C) and high humidity (85-90%) in the sprouting room help produce good quality crispysprouts.

. After washing, soak the beans in tap water at room temperature for eight hours. In the coolseason, use warm water (32 0C) for soaking. Put the soaked beans in containers. Do not fill thecontainers to more than 75% of their capacity to avoid overflowing when the seeds sprout.

Apply a fine water spray or mist uniformly over the seeds at three-to four-hour intervals duringthe hot season Ad six to seven hours during the cool season. Apply just enough water tokeep the sprouts continuously moist without drying.

• A overhead water pipe line fitted with taps and movable water pipe or automatic sprinkler systemconnected to a timer are very convenient for watering.

• Stage 1: Beans are swollen after eight hours of soaking.Stage 2: Seeds start germinating one day after soaking.Stage 3: Seeds germinate fully two to three days after soaking with 1 to 2 cm-long sprouts.Stage 4: Sprouts increase in length to 2 to 3-cm after three to four days soaking.Stage 5: Sprouts attain a length of about 5 cm or more in four to five days of soaking. In most

countries, standard marketable sprouts are at least 5 cm long.Stage 6: Sprouts grow further, reaching a length of 8 to 9 cm after six to eight days of soaking.

Longer sprouts are preferred by consumers in Taiwan.

• Consumer preferences determine the size of sprouts produced. Relative sprout lengths atdifferent stages provide a wide choice.

Transfer sprouts of marketable size from the sprouting containers to drums/troughs or bucketsfor washing Wash and pack sprouts during early morning to avoid spoilage by high temperatureafter sunrise. Remove all broken roots, sprout pieces and other debris while washing.

• Wash with fresh cold water three to four times to separate the seed coats still attached to thesprouts. Remove the sprouts from the drum using a basket or sieve.

. Use plastic bags to pack the sprouts for the market. A kilogram of dry seed yields around eight tonine kilograms of sprouts.

. Vendors in the local market usually sell the sprouts in open containers, but sprouts kept this wayare likely to deteriorate quickly. Well-developed market centers/ supermarkets use specialpackages laminated with cellophane to prevent drying and quick deterioration. To enhance shelflife, keep the sprouts refrigerated.

Vegetable Soybean Cultivation

Vegetable soybean is popular in Japan, Korea, China and Taiwan, and consumption isincreasing very rapidly. Although the vegetable-type varieties of soybean are preferred, the green-shelled beans as well as whole tender green pods of grain soybean can also be used as a vegetable.Grain soybean is already widely cultivated in many countries of the tropics and subtropics, so theproduction of vegetable soybean can be readily adopted. The cultivation practices for vegetablesoybean and grain soybean are similar except that vegetable soybeans are harvested when the podsare still green and full. Generally, the green seeds of vegetable soybean are larger, more tender andsweet. Green-shelled beans can be cooked to make a tasty and nutritious meal or snack.

The importance and cultivation practices of vegetable soybean are described below:

. Vegetable soybean, a rich source of vitamin A, and also good source of carbohydrate, proteinand iron, has excellent potential for enriching the human diet. It is more nutritious than vegetablegreen peas. The pods of vegetable soybean are harvested when they are still green, just beforethe seeds turn yellow.

. The seeds of vegetable soybeans are commonly larger, sweeter and more tender than grain typesoybean. Such green seeds are commonly used in most countries. Even grain soybeans at greenpod stage can be used as a vegetable.

In addition to domestic consumption, vegetable soybean also has export potential. Export marketrequirements are:Hundred seed weight (dry): � 30 g;No. of seeds per pod: � 2Pubescence on pod: grayFlavor: goodPod texture after cooking: easy to squeezeTaste: slightly sweetCooking time: short

Frozen vegetable soybeans are popular in supermarkets of Japan and Taiwan.

The best planting date for vegetable soybean differs with season and location depending upontemperature and daylength. The optimum temperature range for soybean cultivation is 20-30 0Cwith short day length (< 14 hours). However, planting should be avoided at cooler temperaturesduring winter. Loam soil with a pH of 6.0-6.5 is suitable for its cultivation, but the field shouldbe well drained.

At AVRDC, the following suggested cultural management practices are adopted for high yieldsof good quality vegetable soybean. You can make modifications to suit local conditions.

Field preparation: Land tillage makes the soil friable for good germination, increases soilporosity and aeration for healthy plant growth and kills weeds to control weed-crop competitionfor soil nutrients, moisture and light. This in turn helps plant productivity. Plow and rototill thefield.

1 1

Basal fertilizer application: Have soil samples analyzed. The fertilizer requirements aredetermined on the basis of the soil test. The higher the soil nutrient level, the lesser will be thequantity of fertilizer needed. To get a good harvest (7-10 tons green pods per hectare) andmaintain soil nutrient status for consistent productivity, a fertilizer mix containing N, P205 andK20 at the rate of 20-30, 60 and 80 kg/ha respectively is applied by broadcast as a basal doseand incorporated into the soil with final harrowing and leveling of the field.

Use of Rhizobium inoculation: Usually Rhizobium inoculation is not required in fieldswhere legumes are cultivated. But newly opened lands need Rhizobium bacteria inoculations at10 g per kilogram of seed. The use of Rhizobium bacteria culture will promote nodule formationand nitrogen fixation by the plant roots.

Seedbed preparation: The soil should not be too dry at the time of seed bed preparation.Inadequate moisture will result in poor seed germination. At AVRDC, we irrigate the field 3-4days prior to sowing to ensure sufficient moisture in the soil for good germination of seed.Prepare 20-cm raised beds spaced one meter apart from center of one bed to the center of thenext.

Seed treatment and planting: The seed is' treated with protectant fungicides such as captan orthiram at 3 g a.i./kg seed for protection against soilborne fungal diseases. Spacing between rowsis 45 cm and between plants 5-10 cm depending upon seed size and season. Two to three seedsare sown in each hill. However, spacing between rows varies with variety and season. Usuallyseeding (60 to 80 kg seed/ha) is regulated to obtain a population of 400,000 plants per hectare.Sow seeds by hand or by, a hand operated planter.

Top dressing of fertilizer: The first top dressing is done at the rate of 20 kg N + 25 kg K20per hectare along plant rows at flowering for higher pod set. A second application of 20 kg N perhectare is done at the beginning of pod filling stage to improve seed size.

Weed controlt At AVRDC, application of alachlor at 1.5 kg a.i./ha either alone or combinedwith pendimethalin at 0.75 kg a.i./ha as pre-emergence spray is practiced to control weeds.

Intertillage: Intertillage once or twice is beneficial for aeration of root system and to controlweeds which emerge after the effect of chemical weedicides fades off.

Irrigation: Maintaining proper soil moisture throughout the crop growing season is importantfor good quality pods. Usually, first irrigation is needed within a week after sowing underAVRDC soil conditions. Irrigation is done in furrows. Depending upon weather and soilmoisture conditions, the irrigation is continued at 10-15-day intervals until the pods are welldeveloped. However, irrigating the crop is essential at critical periods such as flowering and podfilling stages.

Disease control: Rust may be a serious problem, especially for seed production, causing up to100% yield loss. Tan, dark brown or reddish brown lesions occur on leaves of rust-affectedplants. None of the commercial cultivars are resistant to rust, but rust-tolerant breeding lines havebeen selected at AVRDC. Fungicides such as mancozeb or triadimefon at the rate of 2 kg a.i./haare sprayed at 10-day intervals to control rust in susceptible cultivars.

Downy mildew disease commonly occurs during spring and autumn seasons but it does notgenerally cause yield reduction. The symptoms are pale green to light yellow spots on the surfaceof the leaf. These spots later enlarge into pale to bright yellow lesions. The underside of the leafshows white powdery spores. To control downy mildew, plant resistant cultivars. Forsusceptible cultivars spray fungicides such as mancozeb at the rate of 2 kg a.i./ha dependingupon severity of disease attack.

? 2

Bacterial pustule can cause yield losses of up to 40% in vegetable soybean. Early symptoms ofthis disease are small pale green lesions which become watersoaked with bacterial ooze that driesto become white crust on upper/lower leaf surfaces. The best way to control bacterial pustuledisease is by planting resistant varieties.

Insect pest control: Beanfly is a serious pest of soybean. Beanfly larvae feed inside the plantstem and their damage cannot be recognized easily. Beanfly damage is more severe in relativelycool season (e.g. during autumn at AVRDC) compared to long dry weather conditions (e.g.spring at AVRDC) due to lower insect population. Soybean must be protected against beanfly.For the autumn crop at AVRDC, monocrotophos, omethoate or dimethoate is sprayed at the rateof 0.5 kg a.i./ha at 3, 7, 14, 21, 28 and 35 days after emergence (DAE). The first three spraysare very important and should not be delayed. Spraying is stopped at 35 DAE. In spring, usuallythere is no serious damage by beanfly.

Pod borers may attack soybean but usually they do not cause significant yield loss underAVRDC conditions if we use insecticides for beanfly control.

Stink bug commonly occur on vegetable soybeans late in spring and summer season crops. Theydo not cause any economic damage under AVRDC conditions. However, if you notice highpopulation (i.e. 3 to 4 insects per meter rove) uniformly over the entire field in early pod fillingstage, spray insecticides such as fenvalerate at 100 g a.i./ha or deltamethrin at 30-50 g a.i./ha atweekly intervals till the insect infestation is controlled.

Defoliators feed on leaves. Minor damage does not require insecticide application. However,when the attack is severe, they can also be controlled by the insecticides used for stink bugcontrol.

Stop spraying chemicals at least 10 days prior to harvest. Overuse of insecticides or fungicides ishazardous for human and animal health.

Harvesting: Harvesting is done when 80% of the pods have reached physiological maturitystage. It may take 65 to 75 days after germination for vegetable soybeans to be ready for harvestdepending upon variety, temperature and weather conditions. The pods are still green. InTaiwan, harvesting usually begins at midnight when dew and cool temperature help to preservethe green color and freshness of the vegetable soybeans. When harvested in daytime, the plantsare kept under the shade. The pods are stripped from the plants by hand. Harvesting machineswhich can save labor, cost and time are also available.

Grading is important for export of good quality vegetable soybeans. The diseased and insect-damaged pods and pods with spots and blemishes are sorted out. The good marketable yieldsare:0 pods - 7-10 t/ha, or

green beans - 4-7 t/ha, orwhole plant - 18-25 t/ha

I 3

Seed Production Technology of Garden Peas

S.

Garden peas are one of the four

Shanrnugasundaram

most important seed legumes. It occupies an importantplace among the winter vegetables in India. In the North Indian hills, it is the most important off-season vegetable grown both as a summer and autumn crop. It is cultivated in states likeBihar, TYL9' , Aauonn.MoburobLru,Delhi, West Bengal, Punjab, uodHinoaoboJPradesh. The mostimportant garden pea growing state iu}3.P.which accounts for more than 60 % of production.

In self-pollinated crops like garden pea, hybrid vigor is commonly found when differentpurelines are crossed. Since self-polliooUioo is the general rule, inbreeding is necessary to obtainpozeIiueoin this group of plants.

Whether or not it is economically feasible to use hybrid vigor depends upon the cost ofproducing the hybrid seed in relation to the value of the increased yields. Since most self-pollinatedcrops produce urclativeln small amount of pollen, which is not transferred by the wind or byinsects to any significant degree, hand pollination is most likely necessary to bring about u1rans{erof pollen between plants. If many seeds are produced by each hand pollination then the increasedyield justifies hybridization for greenhouse and early market use. With a crop like garden peas, it isvery unlikely that hybrids will ever be used because of difficulty of hand pollination and the smallnumber of seeds produced per pollination.

The production of quality seeds not only involves the selection of the best and true to typeplants in varieties of different vegetables but also the adoption of specific techniques suited to eachkind. For the production of good quality seeds such information as whether a particular crop isself-pollinated or cross-polliootcd is absolutely oeceaary,as the technique to be used will dependon it.

Seed Production

Seeds of garden peas of almost all varieties can be quite efficiently produced in the NorthIndian plains. Therefore, there seems to be no real advantage in producing pea seed in the hills forsupplying to the vegetable growers in the plains.

The agronomic practices to be followed for crops raised for seed production are the same asfor those raised for commercial green pod purposes. Some of the important aspects of cultivationare:

Soil and Climatic Requirements:

Peas can be in a variety of soils, from light sandy loam to clay though the bestresults are achieved on well drained loose, friable loamy soils, and not in acidic soils. The mostfavorablepH range is between 6.0 uod7.5.

Peas prefer cool weather; they do not grow well during the intense heat of summer. Theblossoms and pod are more susceptible to frost than the leaves uods1e000.Tbe seeds can germinateat nroinicunzo temperature of 50C; the optimum temperature for germination is about 220C. Athigher temperatures, germination is rapid but loss of stand may result from various decayingorganiazom.

}

Early varieties can be sown from mid-October to the first week of November while mid-season varieties can be sown from the last week of October to mid-November. Late varieties can besown up to the end of November.

Seed Rate:

Use 70 to 75 kg/ha for late varieties and 100 kg/ha for early varieties. For the variety Arkelthe seed rate can be increased up to 125 kg/ha.

Inoculation:

Inoculation of pea seeds with pea nodule bacterium culture is recommended when peas areplanted for the first time and also when the crop is to be grown on poor soil. Emulsify the culturematerial in a small quantity of 10 % sugar or gur solution, sufficient to moisten the seed. Heap theseed on a clean floor and moisten and mix thoroughly with the solution. Then spread moistenedseed in a thin layer in the shade to dry and sow in the field in the evening or on a cloudy day.

Spacing:

Use 30 cm for row-to-row spacing for early and 45 cm for mid-season and late varieties.Within-row continuous sowing is done and later on the plants can be spaced at adistanoe of 2 toljozo.l1labor is cheap and adequate then sowing with odibbler with spikes at 3"x7" distance ispreferred.

Fertilizer Use:

A high dose of nitrogenous fertilizer may have a deleterious effect on nodule formation andnitrogen fixation. A small dose of nitrogenous fertilizer (about 25 N/ha ) is necessary to stimulateearly growth ,of legumes. Phosphates increase yield and improve the quality of peas, whereaspotassium appears to increase the yield and nitrogen fixation ability of the legumes. Apply about20 t FYM/ha, 125 kg CAN/ha or 60-65 kg urea/ha, 420 kg Superphosphate/ha, and 100 kg to100 kg Murate of Potash /ha during field preparation.

Irrigation:

For proper germination presoaking is advisable. If the soil moisture is less at the time ofsowing, a light irrigation may be necessary after planting to ensure proper germination. Thereafter,during the dry period, light irrigation may be given at an interval of 10-15 days. One or twoirrigations at the time of flowering and fruit-setting are essential. Light irrigation during frostyweather is also essential to protect the developing flowers and pods from frost damage. Irrigationwith sprinkler is very much recommended.

Isolation:

Since garden pea is a self-pollinated crop, not much contamination is expected in producingpure seeds of a variety. Consequently the only isolation necessary is to have a planting space farenough to prevent mechanical mixtures at planting or harvesting time. However, when producingthe foundation seed, two different varieties should be kept about 20 m.

Roguing:

The term "rogue" as used today applies to any off-type plant. Rogues may originate as aresult of mechanical mixture, volunteer mixture from earlier plantings, natural crossing ormorphological changes caused by mutations.

2

For roguing inspect the pea field at least three, times: (I ) before flowering stage; (2) during

flowering and fruiting; (3 ) during the mature fruit stage.

A high standard of pureness to type allows 1 off-type plant in 200 plants. To avoid

volunteer mixtures do not sow seed on land that has been planted to a different strain within the

preceeding two years.

Harvesting and Curing:

they becomeHarvest the crop from the time the peas become hard in the pod up to the timecompletely mature. It takes about 30 days for the peas to sufficiently mature for germination after

they reach their green stage. Put the vines in small bunches to cure for at least 10 days between

harvesting and thrashing to allow the sweat to pass.

Thrashing:

Thrash the peas as soon as the plants dry. Thrashing can be done with an ordinary grain

thrasher.

Seed Yield:

The seed yield per hectare varies from 1.4 to 2 t. Seed yield as high as 2.5 t are also not

rare.

\`

3

Seed Production Technology of Beans

There are 18 types of beans found throughout the world. Of these, French bean (Phaselousvulgaris L.) lablab beans (Labial) purpureus), cowpea (Vigna sinensis Savi) and cluster bean(Cno ir &y /n /uboI.. Taub. ) are very common and popularly consumed as greenvegetable in India. Except for cluster bean, the seed of the other three beans is also consumed aspulse.

All these crops are self-pollinated and exhibit very little heterosis. Also because of the lessnumber of seeds available in the pods economical commercial hybrid seed production is not

possible. Hybrids can be made by hand emasculation and pollination only 1odevxlope a variety andfor other improvements in the crop. The crops need 50-10 m isolation distance to producefoundation and certified seeds of two cultivars.

French bean

French bean is grown throughout the world as a green vegetable as well as for dry seedconsumption as pulse. It is a self-pollinated crop with only 2-8% outcrossing.

Climate French bean is uvvaoo-aeugoo crop in the hills but it does not thrive well underextremely high temperature. It cannot withstand drought as well as very heavy rainfall and frost.

Even though, muoyculLivars are photo-insensitive, certain cultivars develop floral buds onlyduring short days but would abscise during long days. Suitable soil temperature for good and rapidgermination is 00C. Soil temperature ranging from 18 to 270C induce Rhizoctonia solani

infection in young seedlings. High temperature exceeding 240C for two successive days can causeureduction of 2% in the podsqt for each degree of temperature above 240C to 360F (Davis 1945 ) .SburnmaeLul. (1983) found that 14-190C temperature and 60-70% humidity in autumn season and20-250C and 50-70% humidity in spring season ared suitable for better growth and yield.

Techniques for seed production French bean can be grown successfully in sandy loamsoils. Alkaline and acidic soils should be avoided. To raise a good crop use 15-20 t FYM, 20 kgnitrogen, 60 kg phosphorous, and 60 kg potash. Except for nitrogen, other fertilizers should bemixed in the soil at the time of last plowing.

Before sowing make sure that the soil contains sufficient moisture to attain better andquicker germination. Watering just after sowing or before germination results in germinationfailure. Seeds take 6 to 7 days at I50C soil temperature to germinate, germination is delayed attemperature below 150C.

Sow seeds of dwarf types at a distance of 45-60 cm in rows; plant-to-plant distance shouldbe kept at 15-20 cm. Pole types require 90-I00 cm distance between rows and 30-40 cm betweenplants. Nearly 50-55 kg seed for pole type and 75-100 kg seed for bush type are required to sowone hectare of land.

Apply light irrigation and perform weeding and spraying of insecticide as and whenrequired. Harvest ripe pods by hand. Dry the pods in the sun and thresh by beating with a stick. Ifplants are uprooted then curing must be done at least for 1 week so that pod color turns yellowish.Remove rotten and broken seeds at seed grading. After proper drying, keep the seed in store.

Cowpea (Vigna oimuasio L.)

Cowpea is grown throughout India for its long pods as green vegetable, seed as pulse, andfoliage as fodder. When grown for dry seeds, it is known as black eye pea, kaffier pea, China pea,or southern bean. The cultivars grown for their immature pods are variusly known as asparagus

4

bean, snake bean, and yard-long bean. Cowpea belongs the family Leguminoseae, subfamilyFabaceae.

Soil and Climate Cowpeuoan be grown in almost all types of soils. It is a warm-seasoncrop and thrives best between 21 and 350C. It can be grown successfully in spring summer andrainy season in the North Indian plains. It cannot withstand heavy rainfall and water-logging.Different cultivars respond differently to temperature and daylength and thus these are distinctcultivars for spring summer and rainy season.

Seed Production Techniques

Season and Sowing Cowpea can be grown in spring summer and rainy season. Inlocations where the climate is mild, it can be grown almost throughout the year, but otherwisephoto-insensitive cultivars are grown. In India it is usually sown in February/March in theNorthern plains and in December/January in the South for spring summer crop; for rainy seasoncrop, sowing is done in June/July all over the Indian plains.

Sowing is done in well prepared fields by broadcasting seeds or in line sowing. Usually15-20 kg of seed is required for sowing on 1 hectare depending on cultivar and season. Sowing inlines facilitate better interculture operations and after care. Line sowing can be done by a drilloperated by a tractor, bullocks or manual labor. Spacing between rows should be 45-60 cm andbetween plants 10-15 cm. In case of seed crop, land in which one cultivar of cowpea was grownthe previous year should not be used for growing another cultivars the following year to avoidcontaminations.

Interculture Being a leguminous crop cowpea does not require heavy fertilization. Inoculateseed with Rhizobium culture before sowing. Application of 10-20 kg N, 50-70 kg phosphorous,and 50-70 kg potash has been recommended by Chauhan (1972) .

Cowpea is a shallow-rooted crop and requires less moisture and light irrigation for propergrowth, as it is sensitive to waterlogging. Irrigation prior to flowering helps in pod setting; anotherirrigation should be given after the pods have set. At least one hoeing/weeding after 4 weeks helpscontrol weeds and in root nodulation. Spraying Maleic hydrazide (MH) at 50-200 ppm just beforeflowering was reported to increase the yield of pod (Choudhury and Ramphal 1960 ) .

Maintain an isolation distance of 50 nuDor foundation seed and 25 nu for the production ofcertified seed between two cultivars (Anon. 1971). Ripe and dry pods are harvested by handpicking or by cutting the plants in case of last flush. To avoid shattering of the seeds, harvest whenhalf to two-thirds of the pod has matured. Some cultivars shatter more than others. This problem isnot encountered in ouldvacuwith flashy inflated pods. Threshing is done by beating widha stick orby a thresher. Extreme care should be taken during threshing to prevent injuryl to1heueod.Tbeseeds maintain viability for two years under normal storage conditions.

Labial) Beans

Lablab beans are self-pollinated and partially cross-pollinated by insects. Different cultivarsshould be grown 50 roapart in case of foundation seed ud25roapart in case of certified seed.Lablab beans are indeterminate in response ionho1operiod and there are some short-day and long-d types. Lablab bean is a relatively cool season crop adapted to tropical and subtropical regions.Drought-resistant strains are available and grown as a dry land crop in regions with minimumrainfall. Fruiting starts at the onset of winter and continues throughout the year. Lablab beans aregrown both for green pods as well as dry seeds. Heterosis may not be of much use in this crop butcross-combinations showing heterosis vigor can be used to develop high-yielding purelines.

Seed Production Techniques i~ahlabbeans are annuals of bushy or vining type. When thevines are supported they may grow as high as 6-10 m. They are usaully grown as oso{e crop with

5

staking of the vines. In some places they are grown as a mixed crop with ragi, bajra or sorghum. Itis planted with a distance of about 1 m between crops. The ear heads of the intercrops areharvested first leaving the stalks as support to the vines. The vines grow on them perfectly. If it isgrown as a sole crop it can be sown with a distance of 2.5 x 1.5 m. Three to four seeds are sownper hill and one or two plants allowed to grow on each hill. Dwarf types can be grown at a distanceof 1.0 x 0.75 m line to line and plant to plant. About 20-30 kg seed are required to sow 1 ha ofbush type and 10-12 kg for climbing types.

Lablab beans can be grown in a wide range of soils of average fertility. About 20 kg N,40 kg phosphorus, and 5-6 t FYM are required to grow a good crop in 1 ha of land.Intercultivation can be done to control the weeds until vines spread between rows. Since lablabbeans cannot stand waterlogging, frequent irrigations should be avoided.

Ripe mature pods can be handpicked from the standing crop. Threshing can be done bybeating the pods with a stick, moving a stone roller over the pods, or under letting bullocks tramplethem. Seed should be thoroughly cleaned and dried before bagging. Average seed yield is 6-8 qt/ha.

Cluster Bean

The tender pods are used as a vegetable and in the southern part of India they aredehydrated and stored for use. Cluster bean is a self-pollinated crop, yet some outcrossing, i.e. 2%has been reported. Thus, lesser heterosis is available. Due to less seeds in each pod, economicalcommercial hybrid seed production in cluster bean is not possible.

Seed Production Techniques The crop should be sown in well-drained sandy loam soil.Cluster bean can also tolerate saline and moderately alkaline soils with pH ranging 7.5 to 8.0. Itprefers warm climates and can also be grown in subtropical areas during summer. It prefers long-day conditions for growth and short day for induction of flowering.

Main a row-to-row distance of 45-60 cm and plant-to-plant spacing of 10-15 cm. Seed ratefor line sowing is 15 kg/ha. To improve seed yield, 10-12 kg N, 50-70 kg P, and 50-70 kg K/haare recommended. One or two irrigations are needed in case rains are delayed.

Pull out the plants from the field after proper maturity of the pods. Keep the plants in theleap for curing and proper drying for at least one week. Threshing should be done as in the otherbeans. Store the seeds after proper grading and drying. The average seed yield per hectare is10 qtl.

Pests of Beans

Aphids (Aphis sp.)Jassid (Amrasca kerni)Galerucide beetle (Madurasia obscurella)Pod borer (Adisura sp. Heliothis arinigera)Bean weevil (Callosobruchus sp.)Lygacid bug (Chauliops fallax)Hairy caterpillar (Ascotis imparata)Stem fly (Ophiomyia phaseoli)Root weevil (Stiona lineal:0Bean lady bird beetle (Epilachna varivestis)

a.b.c.d.e.

f.g.h.

J -

6

Disease of Beans

Anthracnose (Colletotrichum lindemuthianum) FungalBean rust (Uromyces appendiculatus) FungalLeaf spot (Cercospora mien/a) FungalPowdery mildew (Etysiphe polygoni) FungalDry root rot and ashy grey blight and wilt and Charcoal rot (Fusarium solani f. sp. phaseoli)FungalBacterial blight (Xanthomonas phaseoli) BacterialBCMV (Bean common mosaic virus )Viral

owed:

a. Anthracnose (Colletotrichum lindeinuthianuin) Fungalb. Dieback (Colletotrichum capsici Syd. Fungal)c. Ashy stem blight (Macmphomhia phaseolina) Fungald. Powdery mildew (Erysiphe polygoni DC) Fungale. Bacterial blight (Xanthomonas vignicola Bunk) Fungale. Mosaic virus virus

Cluster bean:

a. Wilt (Fusariuin sp.)b. Bacterial blight (Xanthomonas cyamopsidis)c. Powdery mildew (Leveillula taurica)d. Anthracnose (Colletotrichunm sp.)

Lab-Lab beans:

a. Leaf spot (Cercospora dolichii Ell.) Fungalb. Powdery mildew (Leveillula taurica) Fungalc. Yellow mosaic virus

a.b.

d.

g.

7

Proceedings of a symposiumon sustainable agriculture

The Role of Green Manure cropsin Rice Farming Systems

25 - 29 May 1987

1988 .The International Rice Research Institute

in collaboration withThe Commission on the Application of Science

to Agriculture, Forestry, and Aquaculture

The International Rice Research Institute (IRRI) was established in 1960 by theFord and Rockefeller Foundations with the help and approval of the Governmentof the Philippines. Today IRRI is one of the 13 nonprofit international researchand training centers supported by the Consultative Group on InternationalAgricultural Research (CGIAR). The CGIAR is sponsored by the Food andAgriculture Organization (FAO) of the United Nations, the International Bank forReconstruction and Development (World Bank), and the United Nations Develop-ment Programme (UNDP). The CGIAR consists of 50 donor countries, inter-national and regional organizations, and private foundations.

I RRI receives support, through the CGIAR, from a number of donorsincluding the Asian Development Bank, the European Economic Community, theFord Foundation, the International Development Research Centre, the Inter-national Fund for Agricultural Development, the OPEC Special Fund, theRockefeller Foundation, the United Nations Development Programme, theWorld Bank, and the international aid agencies of the following governments:Australia, Belgium, Canada, China, Denmark, Finland, France, Federal Republicof Germany, India, Italy, `Japan, Mexico, The Netherlands, New Zealand,Norway, the Philippines, Saudi Arabia, Spain, Sweden, Switzerland, UnitedKingdom, and United States.

The responsibility for this publication rests with the International RiceResearch Institute.

Copyright © International Rice Research Institute 1988All rights reserved. Except for quotations of short passages for the purpose of

criticism and review, no part of this publication may be reproduced, stored inretrieval systems, or transmitted in any form or by any means, electronic,mechanical, photocopying, recording, or otherwise, without prior permission ofI RRI. This permission will not be unreasonably withheld for use for non-commercial purposes. IRRI does not require payment for the noncommercial useof its published works, and hopes that this copyright declaration will not diminishthe bona fide use of its research findings in agricultural research and development.

The designations employed and the presentation of the material in thispublication do not imply the expression of any opinion whatsoever on the part ofI RRI concerning the legal status of any country, territory, city, or area, or of itsauthorities, or the delimitation of its frontiers or boundaries.

ISBN 97-104-189-8

Contents

ForewordSymposium recommendations

KNOWLEDGE AND TECHNOLOGY

Economic feasibility of green manure in rice-based croppingsystems 11

M.W. Rosegrant and Roumasset

Woody species as green manure crops in rice-based croppingsystems 29

J.L. Brewbaker and N. Glover

Green manure in rice the Japan experience 45M. Ishikawa

Green manure cultivation and use for rice in China 63Chen Lizhi

Green rn'anure crops in irrigated and rainfed lowland rice-basedcropping systems in South Asia 71

I.P. Abrol and S.P. Palaniappan

Potential of sesbania as a green manure in saline rice soils inThailand 83

S. Arunin, C. Dissataporn, Y. Anuluxtipan, and D. Nana

Stem-nodulating legumes as green manure for rice in West AfricaG. Rinaudo, D. Alazard, and A. Moudiongui

Farm-level management systems for green manure crops in Asian riceenvironments 111

D.P. Garrity and J.C. Flinn

EFFECTS ON SOIL FERTILITY

Microbiological aspects of green manure in lowland rice soils 131N.S. SubbaRao

Effect of green manure on soil organic matter content and nitrogenavailability 151

D.R. BouldinNitrogen fixation by leguminous green manure and practices for itsenhancement in tropical lowland rice 165

J.K. Ladha, I. Watanabe, and S. Saono

Role of green manure in low-input farming in the humid tropicsJ. van der Heide

185

Transformation of green manure nitrogen in lowland rice soilsS. Nagarajah

193

Green manure management in rice-based cropping systemsO.P. Meelu and R.A. Morris

209

Measurement of nitrogen fixation in crop and shrub legumesM.B. Peoples, D.F. Herridge, and F.J. Bergersen

223

ACIAR-sponsored legume research 239E.S. Wallis and D.E. Byth

Effect of green manure on rice soil fertility in the United States 257M.P. Westcott and D.S. Mikkelsen

Effect of green manure on physicochemical properties of irrigated ricesoils 275

Wen Qixiao and Yu Tianren

INTEGRATED USE OF LEGUMES

Annual legumes for food and as green manure in a rice-based croppingsystem 289

K.R. Kulkarni and R.K. Pandey

Use of perennial legumes in Asian farming systems 301P.K.RrNair

Integrated use of green manure in ricefields in South China 319Liu Chungchu

Use of green manure in rice farming systems in West and NorthwestCameroon 333

A.C. Roy, S.B.C. Wanki, and J.A. Takow

GERMPLASM COLLECTION AND SEEDPRODUCTION

Collection and evaluation of tropical legume germplasm 343R. Schultze-Kraft

Seed production and management of mungbean and soybean 359S. Shanmugasundaram

Participants 376

Seed pro u t on and mana e entof .ungb an n soybean

S. Shanmugasundaram

The seed requirement to plant the world mungbean area is estimated to bearound 68,000 t; for soybean, it is ,156,000t. Current seed supplies cannotmeet that demand. The need to produce sufficient quality seeds inmungbean and soybean is emphasized and preharvest and postharvest seedproduction problems discussed. Future directions for seed production areexamined in the context of innovative concepts and procedures in plantbreeding.

In early agriculture, people grew crops primarily for food.. Each season, they savedsome grain as seed for the next crop. Today, farmers in many countries still followthat age-old practice. In choosing seeds for the next planting, farmers select only thebest (Chin 1969).

Mungbean Vigna radiata (L.) Wilczek and soybean Glycine max (L.) Merr.form important constituents of human food and animal feed. It is estimated thatworldwide mungbean production amounts to about 1.4 million t harvested fromabout 3.4 million ha (Shanmugasundaram and Poehlman 1988). Seed rate forplanting varies with seed size, percentage of germination, and desired plantpopulation density (Morton et al 1982). However, 68,000 t of seeds are required tosatisfy the need of 3.4 million ha of mungbean production. Assuming an averageseed rate of 20 kg/ha, about 113,333 ha of land is needed to produce 600 kg goodquality seed/ha.

In 1985, 52.6 million ha were planted to soybean (Table 1), about 49% of thearea in North and Central America, 27% in South America, and 20% in Asia. Withan average seed rate of 60 kg/ ha, it is estimated that 3,156,000 t of seeds are needed.About 2,104,000 ha of land is required to produce an average 1.5 t good qualityseed/ ha.

The objective in seed production is to maximize the production of seed withsuitable germination capacity (Bowring et al 1978). In the United States in 1983,certified soybean seed was produced on 387,445 ha, 36% of the total soybean area.The soybean seed requirement in Thailand was 7,000 t in 1983, but the governmentproduced only 980 t (Potan 1987). In Indonesia, only 30% of the total area is plantedwith seeds of improved cultivars (Djauhari et al 1984).

362 GREEN MANURE IN RICE FARMING

tropics and subtropics has received attention (Dassou and Kueneman 1984,Kueneman 1983, Opefia et al 1987, Shanmugasundaram 1976, Shanmugasundaramand Poehlman 1988).

Successful quality seed production will depend on incorporation of geneticallycontrolled quality traits with desirable agronomic ones. I-lard seeded ness is knownto improve seed resistance to detrimental environmental influences (Potts et al1978). Other characters with similar influences are seed coat thickness (Caviness andSimpson 1974), pod thickness or composition (Hartwig and Edwards 1970), andresistance to seedborne diseases (Wilcox et al 1975).

In the past decade, a number of new mungbean and soybean varieties werereleased to farmers. But seed quality characters have yet to be incorporated into newvarieties.

Seed categories

Genetic improvement must be associated with good seed certification. Farmersshould have access to good, relatively affordable seed (Walker 1980). But seedproduction, inspection, certification, processing, distribution, and marketing varywidely among countries.

The steps to produce the various categories of seeds described here apply tomungbean and soybean. Seed multiplication rates vary with the crop.

The plant breeder carefully selects for various traits (with adaptability and highyield considered essential) and identifies a line as suitable for release. The identifiedline is unique in a number of qualitative and quantitative traits. However, certaindistinct traits are uniform and stable. These distinguishing characters are consistentand relatively easy to use for a specified region of adaptation.

For example, when a new soybean variety is released in the USA, characterssuch as seed coat color, hilum color, flower color, pubescence color, stemtermination, leaf type, USA maturity group classification, pertinent diseaseresistance or susceptibility, and protein and oil content are described. Foundationseed is produced from the basic breeder seed. Registered and certified seeds areproduced by selected farmers. Methods of seed production by the plant breeder,maintainer, seed merchant, and progressive farmer depend on the crop species andon the breeding system (Bowring et al 1978).

The plant breeder's responsibility is to maintain the pedigree seed (Fehr 1978)or the prebasic seed (Bowring et al 1978). Basic seed is produced from pedigree seed.A plant breeder supervises production of these two seed categories of seed, makingsure that the variety is pure and free from variations that are not described as part ofthe variety. Pedigree and basic seed also should be free from weed seeds andextraneous materials.

A variant is defined as plants or seeds described as part of the variety, butdifferent from the norm for the variety (Otto 1985). In soybean, natural mutationcan cause changes in plant or seed characteristics. Brown and black seed coatmutants are common in yellow seeded soybean; these offtypes should be removedduring purification (Fehr 1978).

SEED PRODUCTION AND MANAGEMENT OF MUNGBEAN AND SOYBEAN 363

Mungbean and soybean are self-pollinated, annual species reproduced bynormal fertilization. In mungbean, natural outcrossing varies from 0.0 to 13%(Shanmugasundaram and Poehlman 1988). A high level of outcrossing can causeconsiderable variation in the seed produced. In India, when rnungbean seed wasproduced, a 1.5-m border was left unharvested between adjacent varieties (Kernick1961). Considering the large extent of outcrossing in some genotypes, the isolationrequirement has been increased to 3 m.

Usually, a plant breeder maintains a variety by planting single plant progenyand checking characteristics against the variety's official description. If the rows areuniform, they are bulked. In soybean, 30-50 kg of pedigree seed normally is reserved.In rnungbean, .10-15 kg of pedigree seed is reserved. In temperate and tropicalcountries, seed production rates vary because of the length of growing seasons andthe yield potential of varieties. Pedigree seed is planted on 0.5-1.5 ha to produce 1-3 tsoybean and 0.3-1 t rnungbean basic seed.

Basic seed is used to produce the subsequent categories of seeds (Shanrnuga-sundaram 1982). At each stage, care is exercised to remove variants. In countrieswith official seed certification programs, designated agencies supervise and regulateseed certification.

In India, a parastatal national seed corporation coordinates the production ofcertified seed through a series. of state seed farms that are profit-responsible. Theywere set up and funded by World Bank (Walker 1980). The All-India CoordinatedResearch Project on Soybean, in its annual meeting, allocates to each breeder thequantity of seed to be produced. For example, in 1985-86 breeders produced about92 t of basic seed of 20 new soybean varieties (P. S. Bhatnagar, pers. comm.).

Factors to consider in seed production

Seed production is a specialized activity. Preharvest and postharvest factors must beconsidered (Nangju et al 1978): field environment, cultural practices, geneticinfluence, and harvest time (Tekrony et al 1978) and biotic and abiotic factors(Roberts 1972b, Sinclair and Jackobs 1982).

Basic constraints in seed production can be varietal (genetic characteristics),environmental, biological, and socioeconomic, alone or in combination. Vagaries ofclimate and soils must not be used as excuses for deficiencies in plant genetics,selection procedures, isolation distances, good crop management, and qualitycontrol (Walker 1980).

Constraints such as photoperiod, temperature, soil properties, and rainfallcannot be controlled by the seed producer (Shanmugasundaram and Tsou 1987).Land preparation, organic or inorganic fertilizer applications, pest and diseasecontrol, and weed control and management are factors that can be regulated. Asufficient knowledge pool is available (for a review see Morton et al 1982, Nangju etal 1978, Scott and Aldrich 1970, Shanmugasundaram 1982, Shanmugasundaramand Tsou 1987, Sinclair and Jackobs 1982, Tekrony et al 1978). Although obtaininga high yield is a consideration, the most important criterion is producing good


quality seed. Since the price of seed is generally higher than the price of grain, extramanagement inputs are justified.

Preharvest factorsSeed longevity and field weathering. At the Asian Vegetable Research andDevelopment Center ( AVRDC ) , soybean can be planted in the February, July, andScptonuberseasons. TbcFebruary crop encounters rain at harvest (Fig.|).The Julyrainy season crop may be exposed to typhoons. Field weathering of seed is acommon problem in both seasons. Therefore, the seed quality of February and Julyseason crops generally is not dependable. The September season CrOp produces thebest quality seed (Sb0000ugasuoduranuaod Tsou 1987 ) . The seed quality of rainyseason crops, in general, is poor in Indonesia, Thailand, Philippines, Sri Lanka, andNigeria(Arulnaudhy 1987, Nau

'

uut al 1978, Potan 1987, Sumarno 1987).One of the best ways to prolong seed longevity and combat field weathering of

soybean is through genetics. At the International Institute of Tropical Agriculture/llT/\\ and at AVRDC, obtaining good seed quality is a key breeding objective.

Varietal differences in seed deterioration in storage w observed ' o soybeana*c wasvo in

(Wien and Kucocnouo1981). Freshly harvested seeds of /\[}S 2, a pure line from anIndonesian introduction; [`&/ from India; and /\[}S 29 from AVRDC maintainedabout 80% germination for about 6 .mo at ambient room temperature in Bangladesh.Locally grown variety Bragg and /\[}S 66 from AVRDC can be stored for only 2-3mo (Fig. 2). Small-seeded varieties from Indonesia and black seed coat varietiesdeteriorate more slowly than large-seeded varieties. However, reports on the role oflarge and small seeds in seed longevity, germination, emergence, and yields have

Temperature (OC) Precipitation (mm)40 1 1700

500

400

300

200

100

0

600

30

20

10

0J F M A M J J A S 0 N D

MonthI. Maximum and minimum temperature and rainfall pattern at AVR DC in 1984 and time of planting andharvest.

\\and


been contradictory (Edwards and Hartwig 1971, Fontes and Ohlrogge 1972, Greenet al 1965, Johnson and Luedders 1974, Ndunguru and Summerfield 1975). Somechanges associated with seed deterioration are reduced protein synthesis, reducedability to utilize labeled glucose, reduced respiration, and increased respirationquotient (A. Knapp, pers. comm.). Although small seeds are associated with betterseed longevity, the reasons are not yet understood.

Seed vigor is an elusive and complex concept.Vigorous seeds are "likely to .. .perform particularly well in the field, better than others which may be equallysatisfactory in the laboratory test" (Heydecker 1972). Loss of seed vigor due toweathering precedes loss of seed viability. Assessing seed vigor is problematic forseedmen (Kuenernan 1982). The concept of seed vigor and its importance to seedproduction were described by Heydecker (1972) and Perry (1978). A modifiedaccelerated aging and hot water stress test were used to screen for seed longevity andvigor.

In the accelerated aging stress test, seeds are kept at 42 °C and 100% relativehumidity (RH) for 48 h, followed by a laboratory germination test (Byrd andDelouche 1971). To distinguish cultivars with good and pOOr seed storability, Wienand Kueneman (1981) used a modified accelerated aging stress technique. After podsdried, they threshed the seeds and subjected them to 75% RH at 40 °C for 6 wk,followed by a laboratory germination test.

Germination (%)

100 -

80

60

0 AGS 2AGS 29

V AGS 66V AGS 1290 Pb-l(check)

Bragg (check)

20

1 Jan 1 Mar 1 Apr 1 May 15 May 1 Jun 15 Jun 1 Jul

Date of germination test

2. Germination percentage of 6 soybean varieties evaluated at different intervals after storage at ambienttemperature. Bangladesh, 1985.

40


Hot water pregermination stress includes soaking seeds for 70 s in 75 'C waterand rinsing in tap water prior to determining germination or emergence (Kueneman

( g82).Kueocooan(] q83 ) evaluated the F I seeds of reciprocal crosses between soybean

genotypes with good and poor seed longevity using the accelerated aging method.He found significant reciprocal differences, and suggested the possible influence ofthe maternal plant genome on seed longevity. The pooled F 2 variances were largerthan pooled parental variances, which indicated the influence of the genotypes.Differences between reciprocals of the F 2 seed, although relatively small comparedto those between F, reciprocals, were significant, indicating that cytoplasmic geneaction for seed longevity may also be involved, but its effects are probably small.Because of the influence of the maternal plant, expression of segregation is delayedone geoeratioo(Koeoeouau 1983). `

Dassou and Kueneman (1984 ) subjected physiologically mature pods to a

weathering technique in an incubator a{30 °C and 90-95% relative humidity ( RH )

for 10 d. They identified several genotypes resistant to both seed weathering and

deterioration in storage (Table 3 ) . Paschal and Ellis ( 1978 ) reported that genotypesPI 205912, P1 205907, [»[ 341249, PI 279088, and {/1 219653 could be used forbreeding soybean with resistance to field weathering and to seed deterioration instorage.

An early-maturing variety can be used to avoid weathering damage. In Taiwan,for example, spring soybean is planted in February-March and harvested in roid-May.Hovvovez ` early maturity is not a dependable alternative. In some years, rainsmay come early and spoil the crop.

Manipulating the cropping pattern also can be used to avoid field weathering in

the rainy season. In Pakistan, soybean for seed is planted July-August and harvestedOctober-November (Beg 1987). In East Java, Indonesia, lowland and upland

soybeans are planted year-round. Seed for the lowland rainy season and dry season

Table 3. Genotypes resistant to seed weathering and to deterioration in storage.

Hard After incubator After ambientseeda weathering storagebGenotype Origin

1 00'noed Seedwt (g) color

I NDO 153 Indonesia

IPA DO 131 IndonesiaI P4 DO 243P Indonesia1 WOD226 Indonesia104 DO 255 Indonesia

INDO 173A IndonesiaFort Lamy USALee A USABiloxi 3 ChinaAVRDC 8457 Taiwan

9.7 Black 36.0 54.2 8710.2 Black 24.6 35.4 92

8.9 Black 17.2 42.9 909.3 Black 27.2 46.2 80

10.1 Black 30.6 32.6 91

1 0.8 Black 52.6 32.9 81

10.5 Black 46.6 56.2 809.0 Black 62.0 58.5 88

10.5 Black 37.2 50.4 716.1 Black 64.0 58.7 77

Source: O0000uond Kueneman 1984.bm

Nonimbibino seed after 1 h soaking in water. Stored forO mo at 25 0 C and 50 to 95% relativehumidity.


crops comes from the second upland dry season crop. Seed for the second dry seasoncrop comes from the first dry season crop. Only the grain of the rainy season crop isused (Fig. 3). Similar seed production strategies are used in other countries (Potan1987,Sncnarno 1987).

Water management. Water management is closely associated with fieldweathering in both soybean and rnungbcaooeed production ( Huck and Davis 1976,Morton et al 1982). Soybean that undergoes alternate wetting and drying in the fieldhas poor seed quality caused by rapid differential absorption of water by localizedtissues in the seed coat (Moore 1971, 1972). Plasmolysis and deplummoo\ysia at

different stages of seed development can result in external and internal seed injuries(Min / 1957). Damage caused by on-and-off excess moisture also has been observed in` z*

i

rouogbeao(it C. Imrie, pers. comm. ) . Overhead sprinkler irrigation and rain at

harvest can cause wetting and drying of pods. Therefore, from the R 5 growth stage

on, either flood or furrow irrigation is suggested to obtain good quality seeds.

During the dry season, when good quality seeds can be produced, adequate soil

moisture at flowering (IR | and R 2) and seed filling (R 5 and R6) ( Fehr and Caviness

1977 ) is essential.Location. Some locations are more suitable for good quality seed production

than others. Low relative humidity and cooler temperatures are the two key factors

to consider in selecting a location for soybean seed production (Harrington 1963 ) .

Moogbeunis a hot weather crop, but humidity and rainfall should be low for goodquality seed production (Morton et al 1982 ) . Locations with a cool, dry season are

excellent for soybean seed production. In Pakistan, the cooler foothills of Hazara,Swat, and Parachinar are excellent sites for soybean seed production. Seed

3. Flow of soybean seed between locations in different seasons in East Java, Indonesia (source: personaldiscussions with farmers, extension staff, and researchers ) . The arrows show seed flow.

Dry season 1 Dry season 2

Local variety

Localvariety

VMS

368 GREEN MANURE RICE FARMING

produced in those areas is distributed to other areas (Beg 1987). In Indonesia,soybean seed is produced during the dry season in Sumatra and transported to Javafor planting. Distance, mode of transportation, type of packing material, andhandling are important considerations in seed quality.

Pest management. Because seed is a high value crop, seed quality is animportant consideration. In seed production, weed, insect, and disease control usingrecommended management practices is mandatory. Weeds can compete with a cropand restrict the use of nutrients, reducing crop quality. Weeds can also harbor insectvectors that may transmit various virus diseases and can serve as hosts for variousfungal and bacterial diseases. Many leguminous weeds are hosts for soybean rustPhakopsora pachyrhizi and can serve as a reservoir of initial inoculum to createepidemics on soybean. If the field is weedy, the seeds can be contaminated with weedseeds during harvest (Nangju et al 1978).

The stink bug Nezara viridu/a in soybean and various pod borers in rnungbe"anand soybean can reduce seed quality (Morton et al 1982, Todd 1982). The beanflyA/felanagronomyza sp. and others can reduce seedling vigor and impair seed quality.It is imperative to monitor insect pest incidence and adopt appropriate, timelycontrol measures.

Christensen (1972) tested thousands of soybean and seed samples over 20 yr todetermine storage fungi invasion-of seeds prior to harvest. He concluded that there isno significant invasion of seeds by storage fungi.

Fungal pathogens that can cause a reduction in seed quality in soybean are podand stem blight and seed decay Phomopsis spp. = Diaporthe phaseolorum var.sojae; anthracnose Coiletotrichunl dematium var. truncata; and purple seed stain('ercospora kikuchii (Sinclair 1982). In the absence of genetic resistance, chemicalcontrol of these diseases is important.

Among the soybean viruses, soybean mosaic virus (SMV), tobacco ringspotvirus (TRSV), and tobacco streak virus (TSV) may be important (Sinclair andShurtleff 1975). In mungbean, yellow mosaic virus (YMV) is the most importantvirus disease. Vector control and planting resistant varieties are the only means ofcontrolling virus diseases.

Postharvest factors

A seed begins its existence well before it is harvested. Preharvest conditions cancause varying amounts of seed deterioration even before harvest (Roberts 1972a).

Harvesting and drying

Within a season, the time of harvest can affect seed viability (Roberts 1972a).Harvesting should be done promptly on maturity. Harvesting seed with excessivemoisture or too low moisture content can also damage quality. If the crop has to beharvested before full maturity, but after physiological maturity, it should be driedslowly under moderate temperature. Slow drying prevents shriveling due to rapidloss of moisture. After physiological maturity, seeds of both soybean and mungbeanmay begin to sprout during the rainy season while the plants are still in the field.


Under those circumstances, it is better to harvest at the onset of rain and dry theplants in a well-ventilated area. They can be air-dried slowly to enable threshinglater.

Threshing and cleaningHigh cylinder speeds of combines or threshers will result in multiple fractures anddeep-seated bruises, especially in large-seeded soybean or mungbean and in seedswith lower moisture content (Moore 1957, 1972; Roberts 1972a). A 700 rpm cylinderspeed is better than 1155 rpm. Soybean seeds impacted at 12-16% seed moisturegerminated satisfactorily; those impacted at 8-10% and 18-20% moisture germinatedpoorly (Bunch 1960).

In developing countries, soybean and mungbean usually are threshed by hand,either by beating pods inside a bag with sticks or by trampling with animals or smalltractors. Such harsh treatment can result in mutilated seeds. Studies at IITA showedthat combine threshing is inferior to hand threshing and beating pods inside a bag(Nangju et al 1978). Possibly the cylinder speed was not set properly or the seedmoisture content at threshing was too low.

After threshing, the seeds should be cleaned to remove plant debris, weed seeds,dirt, and other extraneous materials that favor seed deterioration. The seeds shouldbe examined for purity and variants should be removed. Seeds with mottling due toSMV should be removed.

Testing for viability and longevityA number of factors can influence seed quality and viability during production.Poor seed with low viability will be even poorer after storage. Therefore, seed lotsneed to be examined before storage. A good-looking seed may not necessarily begood quality. Seed viability is usually measured when the seed is planted, but it isalso measured for industrial purposes (MacKay 1978). Incubator germination, fieldemergence, tetrazolium, seedling growth rates, and seed leachates are some of thetests used to evaluate seed viability (Kueneman 1982, MacKay 1978).

Genotypic differences in seed longevity have been reported (Kueneman 1983,Paschal and Ellis 1978). Within a variety, a number of preharvest and postharvestfactors can influence seed longevity. These tests of seed longevity have beenproposed: seed storage (normal aging of seeds), accelerated aging stress, cold stress,hot water pregermination stress, osmotic stress, thermo stress during germination,and methanol stress (Kueneman 1982). Accelerated aging, pregerrnination, thermo,and methanol stress are recommended for use in breeding for seed longevity.

Seed storageFactors to consider in storing seeds until planting are initial seed moisture content,genotype, temperature, RH, the container in which the seed is packed, and themethod of packing. At AVRDC, seeds are sun- or air-dried to 8% moisture contentfor medium-term storage at 2-5 °C and 40-45% RH. Under these conditions,soybean seed can be stored for 20 yr (AVRDC 1985, Cromarty et al 1982). With8.1-9.4% seed moisture content, soybean seed can be stored at 10 ° C for 10 yr; at 13%


Table 4, Equilibrium moisture content of soybean at 25 0 C at 30-95% relativehumidity (RH) (Roberts and Roberts 1972).

Equilibrium moisture content at given RH

1 0% 30% 45% 60% 75% 95%

4.3 6,5 7.4 9.3 1 3.1 18.8

moisture content, it can be stored for 3 yr. At 20-30 °C, seed with 13-18% moisturecontent will remain viable for less than a year (Toole and Toole 1946). Undertropical conditions, high initial quality soybean seeds at 9-9.5% moisture content canbe safely stored 9 mo at 20-25 °C and 50-60% RH (Gregg 1982). Most AVRDCbreeding materials with good initial seed quality and 9-10% moisture content arestored at 20-24 °C and 55-60% RH. The majority of the entries stored under theseconditions retained more than 80% viability for at least 2 yr. Similar storageconditions are suitable for mungbean.

If storage conditions have a higher RH, there is no need to dry the seed to lessthan equilibrium moisture content. At 45% RH or lower, seed should be dried to7.4% moisture content or lower. At 60% RH, drying the seed to 9% moisture willsuffice. Soybean seed moisture content at 25 °C with different relative humiditylevels are given in Table 4.

The usual rule of thumb for storage conditions for the short term is percent RHand degrees Fahrenheit totaling 100 or less (James 1961).

The viability of soybean is determined using an age index concept.

Age index (AI) = months in storage X Io'""( X 100.06451

Where MC = moisture content (%), T = temperature (°C), and months in storage =Log AI-0.143M C-0.0645T.

Fungi activity during storage below 75% RH is very low; below 62% RH, allstorage fungi are completely inactive (Roberts 1972a). Below 60% RH, storageinsects are inactive. Because rnungbean weevil is a serious storage pest, it is

.important to maintain RH below 60% and seed moisture content below 8% (Roberts1972a).

The minimum germination required for seed certification varies amongcountries. For soybean, it is 80% in the US, but many seedmen demand 90%(Tekrony et al 1978). In India, it is 70%. For mungbean, minimum germination inIndia is 75% (Agrawal 1980).

Under ambient conditions, mungbean appears to be storable longer thansoybean (Table 5). Traditional mungbean varieties appear to have a high proportionof hard seeds, but hard seededness decrease with age in storage. Mungbean seedloses hard seededness with a year (Pathwardhan 1927).

During domestication, the hard seededness character was selected out. Itappears probable that this trait in mungbean can be used in breeding for good seedquality (B. C. Irnrie, pers. comm.). Soon after harvest, hard-seeded rnungbeangermination is low, but it improves with storage (Rajasekara Mudaliar and


Table 5. Germination of quality seed tested after different durations in storage at ambient con-ditions in Delhi, India (Agra al 1980).

CropGermination (%)

0 3 mo 6 mo 12 mo 18 mo 24 mo 36 mo 37 mo

Mungbean cultivar P. S.-16 . 99 99 99 99 98 98Soybean cultivar Bragg 94 93 81 43 14 0 0 0

Table 6. Germination of soybean seed stored in different containers at amieientroom temperature and cold room for different durations in Sri Lanka( Aruinandhy 1987).

Storage period( mo.)

Storage conditionGermination (%)

Gunny bag Polyethylene bag

0 Ambient 90 90Cold 90 90

3 Ambient 80 81Cold 88 80

6 Ambient- 2 70Cold 79 81

Sundararaj 1954). Even after 1 1 yr of storage, hard-seeded mungbean had 70%germination (Sonavene 1928). In soybean, a certain proportion of hard seeds in avariety seems to improve seed longevity and germination (Potts et al 1978).

Because farmers in the tropics do not have sophisticated cold storage facilities,practical storage methods need to be developed. Harrington (1963) suggested usingsteel bins with steel lids, or steel drums with an aluminum foil layer and a gasket seal,sealed tin cans, hermetically sealed glass jars, sealed aluminized polyester pouches,or sealed high-density polyethylene bags. Metal drums with gasket seals arecommon in Taiwan. Sealed polyethylene bags kept in a shaded area can safely storeseed for 6-9 mo (Table 6). Vaporproof packages for storage protect seed from drasticfluctuations in RH. For a detailed review on this topic, see Delouche et al (1973),Delouche (1975), and Nangju et al (1978).

Although storage facilities, low RH, and temperature are known to ward offmungbean weevil, such facilities are unavailable in developing countries in thetropics. Asian villagers traditionally have used peanut oil to protect pulse grainsagainst storage insects. Results at AVRDC suggest that peanut oil or soybean oil at2-3 ml/ kg of seed can effectively suppress weevil reproduction in stored mungbeanfor 3 mo (AVRDC 1976).

In India, treatment with neem oil, activated clay, and red earth is common.Asian farmers also mix seeds with ash to prevent moisture buildup.

If the integrity of the seed is violated before or after harvest, then the seed isvulnerable to damage by biotic factors. Almond moth Ephestia mute/1a can develop


on soybean in storage. An intact seed coat is an effective barrier to infestations.Soybean saponin extracts have been .

found to inhibit development of mungbeari

weevil and soybean almond moth. The saponins or their glucosides seem to producetypical antibiotic symptoms (Sirisingh and Kogan 1982).

Future of seed production

Rapid advances in innovative breeding concepts and procedures will surely modifyconcepts of crop varieties in the future ( Jensen 1 965). In soybean, there are blends,mixtures of two or more pure lines, multiline varieties, and short breeding cycle

varieties ( less uniform ) ; there is a potential for hybrids and genetically engineered

varieties. Some of these will not conform to the variety norm of purity, homogeneity,and distinctness. Seed production and certification of these new products will be a

challenge (Jensen 1965, Lafever 1985). The products will have greater variability forplant type. The working philosophy of the future will emphasize performance overuniformity. In such cases, seed certification probably should monitor seed qualityrather than distinctness.

Diagnostic tests for germination should include rapid vigor tests, disease tests,

seed treatment tests, and variety identification tests (Voris 1985). A simple,

inexpensive, and practical way to efficiently produce, harvest, thresh, clean, andstore good quality seed for small farmers is needed. The mechanisms involved inprotecting against insects using home remedies such as peanut oil need furtherexploration. Research also should focus on the reasons for good seed quality withsmall seeds and black seeds, with or without hard seededness. The role of theenvironment at different stages of seed development and its relevance to seeddeterioration deserve further study. Because farmers are interested in storing seed

at most for 6-9 coo, research with that objective should be distinguished fromcommercial concerns for longer term storage.

There is growing awareness, even in developing countries, of the need to obtainquality seed for planting. Farmers consider it an important single investment that is aprerequisite-if all other management inputs are to pay off. But both government andprivate industry are unable to meet the demand or provide good quality seed. Theprice of certified seed is almost double the price of regular seed (in Thailand, regular

seed costs US$1.40/kg; certified seed costs $3.0/kp)(Potao 1987). However, the

government offers subsidies or other means of obtaining quality seed. Governmentsalso should encourage the private seed industry to meet local demand withoutunduly exploiting the farmers.

.SEED PRODUCTION AND MANAGEMENT OF MUNGBEAN AND SOYBEAN 373

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NotesAddress: S. Shanmugasundaram, Asian Vegetable Research and Development Center, P.O. Box 42,Shanhua, Taionn74igg , Taiwan, China.

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