Leguminous Vegetable Cultivation


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Leguminous Vegetable Cultivation

  1. 1. Leguminous Vegetable Cultivation and Seed Production S. Shanmugasundaram Introduction Leguminous vegetables have been cultivated for more than 6,000 years in different parts of the world. Legumes for human consumption constitute about 5% of the cultivated crops. World production of selected vegetable legumes are given in table 1. Table 1. Area and roduction of selected ve getable le Ve etable Countr / Region Area (ha x 1000) Green peas World 802 Asia 89 Green beans World 391 Asia 102 Dry peas World 8,428 Southeast Asia 27 Dry beans World 25,959 Southeast Asia 1,437 Soybeans World 52,600 Asia 7,500 ions and the world Production (t x 1000) 4,699 144 2,527 636 11,361 22 14,637 1,082 96,000 10,000 In countries like India where majority of the population are vegetarians, leguminous vegetables 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. Most leguminous 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 by the body to absorb vitamin A. Although leguminous vegetables are deficient in some of the sulfurcontaining aminoacids, they are well compensated when consumed with cereals. In some instances the leaves, tender shoots, and roots are harvested and used as vegetables. The whole seed of some of the legumes are called grain. Seeds of legumes without seed coat and cotyledons split into half are commonly called as pulses in India. Similarly the split pigeon pea, Cicer arietinuin, L. is referred to as dal in India and Pakistan. According to Vavilov all the main centers of origin of cultivated plants have contributed to the cultivated legumes of today. Legumes are rather unique compared to other vegetables in that they can obtain free atmospheric nitrogen through their symbiotic association with the nitrogen-fixing bacteria, Rhizobiwn or Pradyrhizobium, in legume root nodules. The nitrogen fixed in the root nodules are not only available to the plant but they also enrich the soil, in varying amounts, when the plants complete their life cycle. Many leguminous vegetable plants contain toxic substances like trypsin inhibitor { (soybean, Glycine max (L.) Merrill)], rotenone (yam bean, Pachyrhizus erosus L.), and cyanogenic glucoside (hyacinth bean, Lab lab niger L., and Lathyrus sativus L.). There are diverse ways by which the toxic effects of these vegetables can be eliminated rendering them safe for human consumption. 1
  2. 2. 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 crop group. However, in many of the monographs dealing with vegetable legumes published in different 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 of these vegetables are also canned and frozen for the market. Some of the legume seeds are sprouted and are popular in many Asian countries. any legumes are also processed. In international trade leguminous vegetables play an important role. Dry seeds, canned and frozen foods, and processed food products from leguminous vegetables enter the international market where they are important commodities for foreign exchange. Botany Legumes are dicotyledonous annuals or perennials. There are about 480 genera and more than 12,000 species in the family Leguminosae (commonly called the pea family). As a group they contain at least 28 different vegetable crops belonging to 18 genera. Almost all the vegetable crops belong to the subfamily Papilionaceae. When the seeds germinate, in some legumes, the cotyledons remain inside the soil due to limited 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 surface by the rapid elongation and growth of the hypocotyl. Such germination is called epigeal germination. 2
  3. 3. A list of leguminous vegetables commonly grown in South and Southeast Asia are given in table. 2 Table 2. Leguminous vegetables gown in S outh and Southeast Asia. Botanical name Crop l iromosome Edible part no. Beans Adaptation Common, Snap, String Lima bean Tepary bean Adzuki bean Phaseolus vulgaris L. 22 Immature pod, mature seeds Temp. and tropics P. lunatus L. A. Gray Vigna angularis (Wind) Ohwi & 22 22 22 Green seeds Dry beans Immature pod, mature seeds Warm season Dry areas Warm season Mungbean, greengram V. radiata (L.) 22 Green pod, mature seeds, Warm season P. acutifolius Ohashi Wilczek sprouts Blackgram, Urd bean Rice bean V. mungo (L.) Flepper V. umbellate (Thunb) Ohwi and 22 22 Mature dry seeds Mature dry Warm season, dry tropics Warm season Peas Pist nn sativunl 14 Immature, seeds, pods, tender Cool, humid season Peanut, Groundnut Arachis hypogaea L. 40 Mature seed, tender shoots, and Young pods and beans Tropics and subtropics, warm temp. Tropics Ohasi L. Swordbean Canavalia gladiata (Jacq.) D.C. Pigeon pea, redgram Cajanus cajan L. Millsp. 22, 44, 46 22 Chickpea, Bengalgram Clusterbean, guar Cicer arietinum L. Soybean leaves leaves Warm season 16 Young green pods, seeds, mature seeds Green pods, tender shoots, dried 14 Young tender pods Dry tropics Glycine max (L.) Merr. 40 Tropics to 52°N Hyacinth bean, lablab bean Grass pea, Chickling pea Lentil Yam bean Lab lab purpureus (L.) 22 Immature green seed; mature dry seed, sprouts Young pods, tender bean, dried Lathyrus sativus L. 14 Seeds, leaves used Lens culin..aris Medikus Pachyrhizus erosus Urban 14 22 Mature seed Succulent roots Potato bean Winged bean P. tuberosus spreng Psophocarpus tetragonolobus 22 18 Tubers Almost all parts used Winter crop Hot, wet tropics, perennial Perennial Tropical Asia Fenugreek Faba bean, broad bean, Horse bean, Windsor bean Cowpea, Catjang Trigonella foenum-graecum L. Vicia faba L. 7 12 Mature seeds Green beans, dry seeds Winter Temp. cool season Vigna unguiculata (L.) Walp 22 Trop. Africa Yardlong bean, Asparagus bean Bambara groundnut Horsegram V. sesquipedalis (L.) 22 Immature pods, young shoots, dry beans Immature pods Vigna subterranea (L.) Walp Macrotylom.a unifloruin (Lam) Immature and mature seeds Mature seeds Tropical Africa Dry tropics Runner bean Moth bean Phaseolus coccineus L. Vigna aconitifolia (Jacq.) Green pods Green pods, dry whole or split seeds Temperate Tropical Cyamopsis tetragoraoloba (L.) Taub. seeds seeds as herbs D.C. Walp Verde 22 20, 22 22 22 Marechal 3 Cool, dry Dry season Cool season Warm season
  4. 4. Description of Selected Legumes L Snap, String, or French Bean Phaseolus vidgaris likely originated from Central America. It is commonly associated with corn and squash culture in the tropical Latin American countries. It is an annual with epigeal germination. CIAT in Cali, Colombia has classified the world collection of this bean into the following four main types by growth habit: (1) dwarf determinate, (2) dwarf indeterminate, (3) prostrate indeterminate, and (4) climbing indeterminate. Beans are also classified according to use as follows: 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 and also 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 the major 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 11th century BC. It was introduced from China to the USA, Japan, Korea, and South and Southeast Asian countries at different times. Large yellow or green-seeded varieties with gray hilum are preferred for use as vegetable soybeans. Based on latitudinal adaptation soybean cultivars in the USA and Canada have been classified into 13 maturity groups (MG). MG 000, 00, and 0 are early and adapted to extreme north latitudes while MG IX and X are late and adapted to tropical latitudes. However, this MG system 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" since 1943. In 1967 an All-India coordinated Pulse Improvement Program commenced with yield and disease resistance as the primary concerns. A number of varieties have been released (table 3). 4
  5. 5. ri beLan cultivars released in India Table Source/ parents Year Ctdtivar name Location Maturity (days) "T-ileysiap.0 Type 1 as selections Muzaffarpur Shining Mung No. 1 COI CO2 CO3 BR-2 Arndt Khargone-1 R-288-8 Krishna-11 D66-26 Musa-Baisakhi Kuhl bung Type 1 Local PLS 365/3 PLS 367 Bhagalpur Local Bihar Local K 119-56 Local Gwalior Local Local Type 44 1948 1952 1975 1976 1968 U.P. Punjab Tamilnadu Tamilnadu Tamilnadu Bihar Bihar M.P. Rajasthan M.P. Rajasthan New Delhi 60 Improve& characters Ref.2 G, GM 1 2 3 4 4 5 5 5 _ 60 LG, S SG, DL DG SG, IRC MG MY, YMV LG, GM SG LG, GM SG DG, spring and summer SG 65 135 65 70 110-115 90 65 70-75 65 60-65 60-65 5 5 5 5 Local bridization and selection Type 1 x Type 49 1975 Maharashtra 1948 U.P. 60-65 DG, summer, 7 Type 51 4465-4 x Type 49 1962 U.P. 75-80 8 Jawahar-45 S-8 (Mohini) Kanke Multipurpose 1972 1972 1973 M.P. New Delhi 75-80 60-65 9 10 11 ML 1 Madira x UP local BR 2 x T2 Tl x China Moong 781 Hyb. 45 x 23-67 SG, mixed crop SG, kharif SG SG 1973 Punjab 90 G, tolerant to 12 KM I S 8 x PS 16 1978 Tamilnadu 65 YMV, pod 5 NM 5 PS 7 PS 10 No. 54 x Hyb. 45 1981 1981 Punjab New Delhi New Delhi 80-85 60-65 60-65 G, kharif DG, Summer DG, Summer 5 5 5 Kopergaon Developed b Type 44 spring disease borer 6 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 green seed; 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 and Singh 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 with disease resistance were emphasized. The Bureau of Plant Industry and the University of the Philippines Los Banos conduct research and develop new varieties. Indonesia, Thailand, USA, Sri Lanka, and Australia have mungbean breeding programs which have released new improved varieties that are high yielding, carry resistance to powdery mildew and cercospora leaf spot, have synchronized maturity, and large seed size. A list of varieties from AVRDC materials released in different countries are given in table 4. 5
  6. 6. Table 4. AVRDC mun bean selections released as cultivars in different countries Cultivar AVRDC no. Year of Country Improved characters' release HY ASVEG VC 1089-A 1978 Costa Rica HY, UM, LR B angasa V 3476 1980 Korea HY, UM, LR Tainan Sel. #3 VC 1628A 1981 Taiwan 1981 2 2 M 986 VC 156OD India 1982 Australia HY, EM, PW, LR King 1982 Australia V 13882 HY Station 46 VC 1000-45-B 1982 Fiji HY, MMV, RPM, (CLS), UM Seonhwa Nogdu VC 1973-A 1982 Korea HY, MYMV, CR Type 77 VC 1131-B-12-2B 1982 Sri Lanka HY, CLS, R Manyar VC 1089-A 1983 Indonesia HY, (CLS), R Nuri V 2773 1983 Indonesia 3 1983 Malaysia Imara V 1380 1983 Tanzania 3 Station 25 1984 Fiji VC 1007-14-1-5B 3 Station 27 1983 Fiji VC 1160-1-1-2B HY, CLS, RPM, R BPI Mg2 VC 1163 1984 Philippines HY, WA Xu Yin No. 1 VC 1973-A 1985 China 3 Boliche 451 1985 Ecuador VC 1163 KPS No. 1 VC 1973-A 1985 Thailand KPS No. 2 VC 2778-A 1985 Thailand HY, NS< CLS, 'RPM, TDO, UM Walet VC 1163-A 1986 Indonesia HY, NS< CLS, RPM, UM Gelatik VC 1160-22B-1-B 1986 Indonesia BPI Mg4 VC 2764-B DX 102a VC 2768-A DX 113 VC 2763-A 1 HY = high-yielding; UM uniforrn 1986 1986 1986 Philippines Vietnam Vietnam HY, UM, LR, EM, (CLS), RPM HY, SLS-R, RLD NY, TASS, RLD maturing; LR = lodging-resistant; EM = early maturing; PW = resistant to pod weathering; CLS/(CLS) = resistant/moderately resistant to cercospora leaf spot; RLD = resistant to local diseases; SLS-R; Sandy loam soil after rice; TDO = tolerant to damping off; R = rust-resistant; MMV = resistant to mungbean mottle virus; RPM = resistant to powdery mildew; MYMV = resistant to mungbean yellow mosaic virus; CR = resistant to charcoal rot; WA = wide adaptability; TASS = tolerant to acidic and saline soils; NS = nonshattering. 2 Adapted selection developed from AVRDC parental stocks. 3 Reported released but no further information. Through intensive research efforts at AVRDC in collaboration with national program scientists 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 maturity have been incorporated in improved lines. 2„Ve g etable Soybean The most popular vegetable soybeans in Japan are predominantly developed by private seed companies. 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, and Ryokkoh. Kaohsiung No. 1 (KS #1) is a pureline selection from Taisho Shiroge from Japan done at AVRDC. Detailed trials and final assessment for release were done by Kaohsiung District
  7. 7. 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 of Agronomy. 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 Second International 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.) Breeding Vegetable Crops. AVI Publishing Co. Westport, Connecticut, USA. Van der Maesen, L.J.G. and S. Somoatmadja. 1989. Plant Resources of South-East Asia. Pudoc Wageningen. 105 p. Yamaguchi, Mas 1983. World Vegetable. AVI Publishing Co. Westport, Connecticut, 414 p. 7
  8. 8. 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 of soybean in the same field. They use minimum resources and earn a reasonable income. This practice can be easily adopted in other tropical countries where rice-based cropping systems predominate. The no-tillage approach for growing soybean after rice with limited resources produce a high-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-based cropping system wherever rice is a major crop. • The farmers in southern Taiwan grow two rice crops from January to September and a third crop of short duration early maturing soybean from September to December just after harvesting rice without 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 for planting. A bag containing soybean seed is worn around the waist and each person plants about 5 rows 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 rice stubble 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 cm or 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 the stubble 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 straw mulch conserves moisture and suppresses weed growth. • In some low-lying areas, the straw is burnt after spreading. Burning of the straw reduces excess moisture, 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 conditions for 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 and broadcasted on the mulched field. Or, it may be applied just after burning the straw. In the burnt field, 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. 8
  9. 9. At the seedling stage, the crop is usually attacked by beanflies. The adult beanfly may be found on the leaf. The beanfly larva or maggot tunnels through the stem and causes the most serious damage. To control beanfly, spraying of insecticides such as monocrotophos or omethoate or dimethoate at the rate of 0.25-0.5 kg a.i./ha 3-4 days after emergence of seedlings is suggested. The spray is repeated 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 rusttolerant/resistant cultivars, if available. Fungicides such as mancozeb or triadimefon at 2 kg a.i./ha can be sprayed against soybean rust. Spray 2 to 3 times as needed. To reduce the cost of spraying, the fungicide and a compatible insecticide can be mixed and sprayed. If labor is available, 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 per hectare which covers the field very well and also controls weed growth. The crop matures in about 85 to 100 days. Harvesting is generally done manually. • The beans are threshed with a locally developed mechanical thresher. Threshed seeds are cleaned and 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 countries where a variety of mungbean dishes and other products are prepared. The mungbean sprout is a traditional vegetable in China and Southeast Asia. However, mungbean sprout is not well known in South Asia, Africa and most other mungbean-producing countries where a vast potential for its commercial production, consumption and export exists. Mungbean sprout production is a simple germination process which requires neither sunlight 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, sprouting containers and water as inputs. It can, therefore, be practiced even by poor farmers in augmenting their meager resources. Mungbean sprouts serve as a good alternative vegetable and source of income. This is especially true during hot wet summer and rainy seasons when there is acute shortage 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 producing mungbean 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 and naturally nutritious dish. Mungbean sprout production simply involves germination, which can be done indoors throughout the year. It does not require soil and sunlight. • The procedure involved in sprout production includes washing, soaking, sprouting, harvesting and packing. e Small hard-seeded mungbean often has poor germination and weak sprout growth. Large-seeded mungbean is also not so economical since they result in lesser sprouts. 9
  10. 10. • 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 fungicides or 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 with 15% moisture can be safely stored for one year at 10 0 C or below. • Before soaking, wash the seeds in fresh water, stirring vigorously three to four times to allow the empty, broken and light seeds to float. Remove the floating seeds and debris. Repeat washing 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 from light. Darkness ensures bright white and long mungbean sprouts. Moderate temperature (2328 0 C) and high humidity (85-90%) in the sprouting room help produce good quality crispy sprouts. . After washing, soak the beans in tap water at room temperature for eight hours. In the cool season, use warm water (32 0 C) for soaking. Put the soaked beans in containers. Do not fill the containers 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 during the hot season Ad six to seven hours during the cool season. Apply just enough water to keep the sprouts continuously moist without drying. • A overhead water pipe line fitted with taps and movable water pipe or automatic sprinkler system connected 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 at different stages provide a wide choice. Transfer sprouts of marketable size from the sprouting containers to drums/troughs or buckets for washing Wash and pack sprouts during early morning to avoid spoilage by high temperature after 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 the sprouts. Remove the sprouts from the drum using a basket or sieve.
  11. 11. . Use plastic bags to pack the sprouts for the market. A kilogram of dry seed yields around eight to nine kilograms of sprouts. . Vendors in the local market usually sell the sprouts in open containers, but sprouts kept this way are likely to deteriorate quickly. Well-developed market centers/ supermarkets use special packages laminated with cellophane to prevent drying and quick deterioration. To enhance shelf life, keep the sprouts refrigerated. Vegetable Soybean Cultivation Vegetable soybean is popular in Japan, Korea, China and Taiwan, and consumption is increasing very rapidly. Although the vegetable-type varieties of soybean are preferred, the greenshelled 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 the production of vegetable soybean can be readily adopted. The cultivation practices for vegetable soybean and grain soybean are similar except that vegetable soybeans are harvested when the pods are still green and full. Generally, the green seeds of vegetable soybean are larger, more tender and sweet. 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, protein and iron, has excellent potential for enriching the human diet. It is more nutritious than vegetable green peas. The pods of vegetable soybean are harvested when they are still green, just before the seeds turn yellow. . The seeds of vegetable soybeans are commonly larger, sweeter and more tender than grain type soybean. Such green seeds are commonly used in most countries. Even grain soybeans at green pod stage can be used as a vegetable. In addition to domestic consumption, vegetable soybean also has export potential. Export market requirements are: Hundred seed weight (dry): 30 g; No. of seeds per pod: 2 Pubescence on pod: gray Flavor: good Pod texture after cooking: easy to squeeze Taste: slightly sweet Cooking 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 upon temperature and daylength. The optimum temperature range for soybean cultivation is 20-30 0 C with short day length ( 14 hours). However, planting should be avoided at cooler temperatures during winter. Loam soil with a pH of 6.0-6.5 is suitable for its cultivation, but the field should be well drained. At AVRDC, the following suggested cultural management practices are adopted for high yields of good quality vegetable soybean. You can make modifications to suit local conditions. Field preparation: Land tillage makes the soil friable for good germination, increases soil porosity and aeration for healthy plant growth and kills weeds to control weed-crop competition for soil nutrients, moisture and light. This in turn helps plant productivity. Plow and rototill the field. 11
  12. 12. Basal fertilizer application: Have soil samples analyzed. The fertilizer requirements are determined on the basis of the soil test. The higher the soil nutrient level, the lesser will be the quantity of fertilizer needed. To get a good harvest (7-10 tons green pods per hectare) and maintain soil nutrient status for consistent productivity, a fertilizer mix containing N, P205 and K20 at the rate of 20-30, 60 and 80 kg/ha respectively is applied by broadcast as a basal dose and incorporated into the soil with final harrowing and leveling of the field. Use of Rhizobium inoculation: Usually Rhizobium inoculation is not required in fields where legumes are cultivated. But newly opened lands need Rhizobium bacteria inoculations at 10 g per kilogram of seed. The use of Rhizobium bacteria culture will promote nodule formation and 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 3-4 days 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 the next. Seed treatment and planting: The seed is' treated with protectant fungicides such as captan or thiram at 3 g a.i./kg seed for protection against soilborne fungal diseases. Spacing between rows is 45 cm and between plants 5-10 cm depending upon seed size and season. Two to three seeds are sown in each hill. However, spacing between rows varies with variety and season. Usually seeding (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 K20 per hectare along plant rows at flowering for higher pod set. A second application of 20 kg N per hectare 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 combined with 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 control weeds which emerge after the effect of chemical weedicides fades off. Irrigation: Maintaining proper soil moisture throughout the crop growing season is important for good quality pods. Usually, first irrigation is needed within a week after sowing under AVRDC soil conditions. Irrigation is done in furrows. Depending upon weather and soil moisture conditions, the irrigation is continued at 10-15-day intervals until the pods are well developed. However, irrigating the crop is essential at critical periods such as flowering and pod filling stages. Disease control: Rust may be a serious problem, especially for seed production, causing up to 100% yield loss. Tan, dark brown or reddish brown lesions occur on leaves of rust-affected plants. None of the commercial cultivars are resistant to rust, but rust-tolerant breeding lines have been selected at AVRDC. Fungicides such as mancozeb or triadimefon at the rate of 2 kg a.i./ha are sprayed at 10-day intervals to control rust in susceptible cultivars. Downy mildew disease commonly occurs during spring and autumn seasons but it does not generally cause yield reduction. The symptoms are pale green to light yellow spots on the surface of the leaf. These spots later enlarge into pale to bright yellow lesions. The underside of the leaf shows white powdery spores. To control downy mildew, plant resistant cultivars. For susceptible cultivars spray fungicides such as mancozeb at the rate of 2 kg a.i./ha depending upon severity of disease attack. ? 2
  13. 13. Bacterial pustule can cause yield losses of up to 40% in vegetable soybean. Early symptoms of this disease are small pale green lesions which become watersoaked with bacterial ooze that dries to become white crust on upper/lower leaf surfaces. The best way to control bacterial pustule disease is by planting resistant varieties. Insect pest control: Beanfly is a serious pest of soybean. Beanfly larvae feed inside the plant stem and their damage cannot be recognized easily. Beanfly damage is more severe in relatively cool 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 rate of 0.5 kg a.i./ha at 3, 7, 14, 21, 28 and 35 days after emergence (DAE). The first three sprays are very important and should not be delayed. Spraying is stopped at 35 DAE. In spring, usually there is no serious damage by beanfly. Pod borers may attack soybean but usually they do not cause significant yield loss under AVRDC conditions if we use insecticides for beanfly control. Stink bug commonly occur on vegetable soybeans late in spring and summer season crops. They do not cause any economic damage under AVRDC conditions. However, if you notice high population (i.e. 3 to 4 insects per meter rove) uniformly over the entire field in early pod filling stage, spray insecticides such as fenvalerate at 100 g a.i./ha or deltamethrin at 30-50 g a.i./ha at weekly 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 bug control. Stop spraying chemicals at least 10 days prior to harvest. Overuse of insecticides or fungicides is hazardous for human and animal health. Harvesting: Harvesting is done when 80% of the pods have reached physiological maturity stage. It may take 65 to 75 days after germination for vegetable soybeans to be ready for harvest depending upon variety, temperature and weather conditions. The pods are still green. In Taiwan, harvesting usually begins at midnight when dew and cool temperature help to preserve the green color and freshness of the vegetable soybeans. When harvested in daytime, the plants are kept under the shade. The pods are stripped from the plants by hand. Harvesting machines which can save labor, cost and time are also available. Grading is important for export of good quality vegetable soybeans. The diseased and insectdamaged pods and pods with spots and blemishes are sorted out. The good marketable yields are: 0 pods - 7-10 t/ha, or green beans - 4-7 t/ha, or whole plant - 18-25 t/ha I3
  14. 14. Seed Production Technology of Garden Peas S. Shanrnugasundaram Garden peas are one of the four most important seed legumes. It occupies an important place among the winter vegetables in India. In the North Indian hills, it is the most important offseason vegetable grown both as a summer and autumn crop. It is cultivated in states like Bihar, TYL9 ' , Aauonn.MoburobLru,Delhi, West Bengal, Punjab, uodHinoaoboJPradesh. The most important 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 different purelines are crossed. Since self-polliooUioo is the general rule, inbreeding is necessary to obtain pozeIiueoin this group of plants. Whether or not it is economically feasible to use hybrid vigor depends upon the cost of in relation to the value of the increased yields. Since most self-pollinated crops produce urclativeln small amount of pollen, which is not transferred by the wind or by insects to any significant degree, hand pollination is most likely necessary to bring about u1rans{er of pollen between plants. If many seeds are produced by each hand pollination then the increased yield justifies hybridization for greenhouse and early market use. With a crop like garden peas, it is very unlikely that hybrids will ever be used because of difficulty of hand pollination and the small number of seeds produced per pollination. producing the hybrid seed The production of quality seeds not only involves the selection of the best and true to type plants in varieties of different vegetables but also the adoption of specific techniques suited to each kind. For the production of good quality seeds such information as whether a particular crop is self-pollinated or cross-polliootcd is absolutely oeceaary,as the technique to be used will depend on it. Seed Production Seeds of garden peas of almost all varieties can be quite efficiently produced in the North Therefore, there seems to be no real advantage in producing pea seed in the hills for supplying to the vegetable growers in the plains. Indian plains. The agronomic practices to be followed for crops raised for seed production are the same as for those raised for commercial green pod purposes. Some of the important aspects of cultivation are: Soil and Climatic Requirements: Peas can be in a variety of soils, from light sandy loam to clay though the best results are achieved on well drained loose, friable loamy soils, and not in acidic soils. The most favorablepH range is between 6.0 uod7.5. Peas prefer cool weather; they do not grow well during the intense heat of summer. The blossoms and pod are more susceptible to frost than the leaves uods1e000.Tbe seeds can germinate at nroinicunzo temperature of 50C; the optimum temperature for germination is about 220C. At higher temperatures, germination is rapid but loss of stand may result from various decaying organiazom. }
  15. 15. Early varieties can be sown from mid-October to the first week of November while midseason varieties can be sown from the last week of October to mid-November. Late varieties can be sown 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 Arkel the seed rate can be increased up to 125 kg/ha. Inoculation: Inoculation of pea seeds with pea nodule bacterium culture is recommended when peas are planted for the first time and also when the crop is to be grown on poor soil. Emulsify the culture material in a small quantity of 10 % sugar or gur solution, sufficient to moisten the seed. Heap the seed on a clean floor and moisten and mix thoroughly with the solution. Then spread moistened seed 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 to ljozo.l1labor is cheap and adequate then sowing with odibbler with spikes at 3x7 distance is preferred. Fertilizer Use: A high dose of nitrogenous fertilizer may have a deleterious effect on nodule formation and nitrogen fixation. A small dose of nitrogenous fertilizer ( about 25 N/ha ) is necessary to stimulate early growth ,of legumes. Phosphates increase yield and improve the quality of peas, whereas potassium appears to increase the yield and nitrogen fixation ability of the legumes. Apply about 20 t FYM/ha, 125 kg CAN/ha or 60-65 kg urea/ha, 420 kg Superphosphate/ha, and 100 kg to 100 kg Murate of Potash /ha during field preparation. Irrigation: For proper germination presoaking is advisable. If the soil moisture is less at the time of sowing, 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 two irrigations at the time of flowering and fruit-setting are essential. Light irrigation during frosty weather is also essential to protect the developing flowers and pods from frost damage. Irrigation with sprinkler is very much recommended. Isolation: Since garden pea is a self-pollinated crop, not much contamination is expected in producing pure seeds of a variety. Consequently the only isolation necessary is to have a planting space far enough to prevent mechanical mixtures at planting or harvesting time. However, when producing the 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 a result of mechanical mixture, volunteer mixture from earlier plantings, natural crossing or morphological changes caused by mutations. 2
  16. 16. For roguing inspect the pea field at least three, times: (I ) before flowering stage; ( 2) during fl owering and fruiting; ( 3 ) during the mature fruit stage. A high standard of pureness to typ e 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: Harvest the crop from the time the peas become hard in the pod up to the time they become completely 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
  17. 17. Seed Production Technology of Beans There are 18 types of beans found throughout the world. Of these, French bean (Phaselous vulgaris 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 green vegetable in India. Except for cluster bean, pulse. the seed of the other three beans is also consumed as All these crops are self-pollinated and exhibit very little heterosis. Also because of the less number 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 and for other improvements in the crop. The crops need 50-10 m isolation distance to produce foundation and certified seeds of two cultivars. French bean French bean is grown throughout the world as a green vegetable as well as for dry seed consumption 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 under extremely 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 only during short days but would abscise during long days. Suitable soil temperature for good and rapid germination 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 cause ureduction 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 and 20-250C 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 loam soils. Alkaline and acidic soils should be avoided. To raise a good crop use 15-20 t FYM, 20 kg nitrogen, 60 kg phosphorous, and 60 kg potash. Except for nitrogen, other fertilizers should be mixed in the soil at the time of last plowing. Before sowing make sure that the soil contains sufficient moisture to attain better and quicker germination. Watering just after sowing or before germination results in germination failure. Seeds take 6 to 7 days at I50C soil temperature to germinate, germination is delayed at temperature below 150C. Sow seeds of dwarf types at a distance of 45-60 cm in rows; plant-to-plant distance should be kept at 15-20 cm. Pole types require 90-I00 cm distance between rows and 30-40 cm between plants. Nearly 50-55 kg seed for pole type and 75-100 kg seed for bush type are required to sow one hectare of land. Apply light irrigation and perform weeding and spraying of insecticide as and when required. Harvest ripe pods by hand. Dry the pods in the sun and thresh by beating with a stick. If plants 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, and foliage 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
  18. 18. bean, snake bean, and yard-long bean. Cowpea belongs the family Leguminoseae, subfamily Fabaceae. Soil and Climate Cowpeuoan be grown in almost all types of soils. It is a warm-season crop and thrives best between 21 and 350C. It can be grown successfully in spring summer and rainy 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 distinct cultivars for spring summer and rainy season. Seed Production Techniques Season and Sowing Cowpea can be grown in spring summer and rainy season. In locations where the climate is mild, it can be grown almost throughout the year, but otherwise photo-insensitive cultivars are grown. In India it is usually sown in February/March in the Northern plains and in December/January in the South for spring summer crop; for rainy season crop, 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. Usually 15-20 kg of seed is required for sowing on 1 hectare depending on cultivar and season. Sowing in lines facilitate better interculture operations and after care. Line sowing can be done by a drill operated by a tractor, bullocks or manual labor. Spacing between rows should be 45-60 cm and between plants 10-15 cm. In case of seed crop, land in which one cultivar of cowpea was grown the previous year should not be used for growing another cultivars the following year to avoid contaminations. Interculture Being a leguminous crop cowpea does not require heavy fertilization. Inoculate seed 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 proper growth, as it is sensitive to waterlogging. Irrigation prior to flowering helps in pod setting; another irrigation should be given after the pods have set. At least one hoeing/weeding after 4 weeks helps control weeds and in root nodulation. Spraying Maleic hydrazide ( MH) at 50-200 ppm just before flowering 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 of certified seed between two cultivars ( Anon. 1971). Ripe and dry pods are harvested by hand picking or by cutting the plants in case of last flush. To avoid shattering of the seeds, harvest when half to two-thirds of the pod has matured. Some cultivars shatter more than others. This problem is not encountered in ouldvacuwith flashy inflated pods. Threshing is done by beating widha stick or by a thresher. Extreme care should be taken during threshing to prevent injury to1heueod.Tbe l seeds maintain viability for two years under normal storage conditions. Labial) Beans Lablab beans are self-pollinated and partially cross-pollinated by insects. Different cultivars should 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 longd 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 minimum rainfall. Fruiting starts at the onset of winter and continues throughout the year. Lablab beans are grown both for green pods as well as dry seeds. Heterosis may not be of much use in this crop but cross-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 the vines are supported they may grow as high as 6-10 m. They are usaully grown as oso{e crop with 5
  19. 19. staking of the vines. In some places they are grown as a mixed crop with ragi, bajra or sorghum. It is planted with a distance of about 1 m between crops. The ear heads of the intercrops are harvested first leaving the stalks as support to the vines. The vines grow on them perfectly. If it is grown as a sole crop it can be sown with a distance of 2.5 x 1.5 m. Three to four seeds are sown per hill and one or two plants allowed to grow on each hill. Dwarf types can be grown at a distance of 1.0 x 0.75 m line to line and plant to plant. About 20-30 kg seed are required to sow 1 ha of bush 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 lablab beans cannot stand waterlogging, frequent irrigations should be avoided. Ripe mature pods can be handpicked from the standing crop. Threshing can be done by beating the pods with a stick, moving a stone roller over the pods, or under letting bullocks trample them. Seed should be thoroughly cleaned and dried before bagging. Average seed yield is 68 qt/ha. Cluster Bean The tender pods are used as a vegetable and in the southern part of India they are dehydrated 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, economical commercial 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. It prefers warm climates and can also be grown in subtropical areas during summer. It prefers longday 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 rate for line sowing is 15 kg/ha. To improve seed yield, 10-12 kg N, 50-70 kg P, and 50-70 kg K/ha are 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 the leap for curing and proper drying for at least one week. Threshing should be done as in the other beans. Store the seeds after proper grading and drying. The average seed yield per hectare is 10 qtl. Pests of Beans a. b. c. d. e. f. g. h. J- 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:0 Bean lady bird beetle (Epilachna varivestis) 6
  20. 20. Disease of Beans a. Anthracnose (Colletotrichum lindemuthianum) Fungal b. Bean rust (Uromyces appendiculatus) Fungal Leaf spot (Cercospora mien/a) Fungal d. Powdery mildew (Etysiphe polygoni) Fungal Dry root rot and ashy grey blight and wilt and Charcoal rot (Fusarium solani f. sp. phaseoli) Fungal Bacterial blight (Xanthomonas phaseoli) Bacterial g. BCMV (Bean common mosaic virus )Viral owed: a. b. c. d. e. e. Anthracnose (Colletotrichum lindeinuthianuin) Fungal Dieback (Colletotrichum capsici Syd. Fungal) Ashy stem blight (Macmphomhia phaseolina) Fungal Powdery mildew (Erysiphe polygoni DC) Fungal Bacterial blight (Xanthomonas vignicola Bunk) Fungal Mosaic virus virus Cluster bean: a. b. c. d. Wilt (Fusariuin sp.) Bacterial blight (Xanthomonas cyamopsidis) Powdery mildew (Leveillula taurica) Anthracnose (Colletotrichunm sp.) Lab-Lab beans: a. Leaf spot (Cercospora dolichii Ell.) Fungal b. Powdery mildew (Leveillula taurica) Fungal c. Yellow mosaic virus 7
  21. 21. Proceedings of a symposium on sustainable agriculture The Role of Green Manure crops in Rice Farming Systems 25 - 29 May 1987 1988 . The International Rice Research Institute in collaboration with The Commission on the Application of Science to Agriculture, Forestry, and Aquaculture
  22. 22. The International Rice Research Institute (IRRI) was established in 1960 by the Ford and Rockefeller Foundations with the help and approval of the Government of the Philippines. Today IRRI is one of the 13 nonprofit international research and training centers supported by the Consultative Group on International Agricultural Research (CGIAR). The CGIAR is sponsored by the Food and Agriculture Organization (FAO) of the United Nations, the International Bank for Reconstruction and Development (World Bank), and the United Nations Development Programme (UNDP). The CGIAR consists of 50 donor countries, international and regional organizations, and private foundations. I RRI receives support, through the CGIAR, from a number of donors including the Asian Development Bank, the European Economic Community, the Ford Foundation, the International Development Research Centre, the International Fund for Agricultural Development, the OPEC Special Fund, the Rockefeller Foundation, the United Nations Development Programme, the World Bank, and the international aid agencies of the following governments: Australia, Belgium, Canada, China, Denmark, Finland, France, Federal Republic of Germany, India, Italy, `Japan, Mexico, The Netherlands, New Zealand, Norway, the Philippines, Saudi Arabia, Spain, Sweden, Switzerland, United Kingdom, and United States. The responsibility for this publication rests with the International Rice Research Institute. Copyright © International Rice Research Institute 1988 All rights reserved. Except for quotations of short passages for the purpose of criticism and review, no part of this publication may be reproduced, stored in retrieval systems, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior permission of I RRI. This permission will not be unreasonably withheld for use for noncommercial purposes. IRRI does not require payment for the noncommercial use of its published works, and hopes that this copyright declaration will not diminish the bona fide use of its research findings in agricultural research and development. The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of I RRI concerning the legal status of any country, territory, city, or area, or of its authorities, or the delimitation of its frontiers or boundaries. ISBN 97-104-189-8
  23. 23. Contents Foreword Symposium recommendations KNOWLEDGE AND TECHNOLOGY Economic feasibility of green manure in rice-based cropping systems 11 M.W. Rosegrant and Roumasset Woody species as green manure crops in rice-based cropping systems 29 J.L. Brewbaker and N. Glover Green manure in rice the Japan experience 45 M. Ishikawa Green manure cultivation and use for rice in China 63 Chen Lizhi Green rn'anure crops in irrigated and rainfed lowland rice-based cropping systems in South Asia 71 I.P. Abrol and S.P. Palaniappan Potential of sesbania as a green manure in saline rice soils in Thailand 83 S. Arunin, C. Dissataporn, Y. Anuluxtipan, and D. Nana Stem-nodulating legumes as green manure for rice in West Africa G. Rinaudo, D. Alazard, and A. Moudiongui Farm-level management systems for green manure crops in Asian rice environments 111 D.P. Garrity and J.C. Flinn EFFECTS ON SOIL FERTILITY Microbiological aspects of green manure in lowland rice soils 131 N.S. SubbaRao Effect of green manure on soil organic matter content and nitrogen availability 151 D.R. Bouldin Nitrogen fixation by leguminous green manure and practices for its enhancement in tropical lowland rice 165 J.K. Ladha, I. Watanabe, and S. Saono
  24. 24. Role of green manure in low-input farming in the humid tropics 185 J. van der Heide Transformation of green manure nitrogen in lowland rice soils 193 S. Nagarajah Green manure management in rice-based cropping systems 209 O.P. Meelu and R.A. Morris Measurement of nitrogen fixation in crop and shrub legumes 223 M.B. Peoples, D.F. Herridge, and F.J. Bergersen ACIAR-sponsored legume research 239 E.S. Wallis and D.E. Byth Effect of green manure on rice soil fertility in the United States 257 M.P. Westcott and D.S. Mikkelsen Effect of green manure on physicochemical properties of irrigated rice soils 275 Wen Qixiao and Yu Tianren INTEGRATED USE OF LEGUMES Annual legumes for food and as green manure in a rice-based cropping system 289 K.R. Kulkarni and R.K. Pandey Use of perennial legumes in Asian farming systems 301 P.K.RrNair Integrated use of green manure in ricefields in South China 319 Liu Chungchu Use of green manure in rice farming systems in West and Northwest Cameroon 333 A.C. Roy, S.B.C. Wanki, and J.A. Takow GERMPLASM COLLECTION AND SEED PRODUCTION Collection and evaluation of tropical legume germplasm 343 R. Schultze-Kraft Seed production and management of mungbean and soybean 359 S. Shanmugasundaram Participants 376
  25. 25. Seed pro u t on and mana e ent of .ungb an n soybean S. Shanmugasundaram The seed requirement to plant the world mungbean area is estimated to be around 68,000 t; for soybean, it is ,156,000t. Current seed supplies cannot meet that demand. The need to produce sufficient quality seeds in mungbean and soybean is emphasized and preharvest and postharvest seed production problems discussed. Future directions for seed production are examined in the context of innovative concepts and procedures in plant breeding. In early agriculture, people grew crops primarily for food.. Each season, they saved some grain as seed for the next crop. Today, farmers in many countries still follow that age-old practice. In choosing seeds for the next planting, farmers select only the best (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 that worldwide mungbean production amounts to about 1.4 million t harvested from about 3.4 million ha (Shanmugasundaram and Poehlman 1988). Seed rate for planting varies with seed size, percentage of germination, and desired plant population density (Morton et al 1982). However, 68,000 t of seeds are required to satisfy the need of 3.4 million ha of mungbean production. Assuming an average seed rate of 20 kg/ha, about 113,333 ha of land is needed to produce 600 kg good quality seed/ha. In 1985, 52.6 million ha were planted to soybean (Table 1), about 49% of the area in North and Central America, 27% in South America, and 20% in Asia. With an 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 quality seed/ ha. The objective in seed production is to maximize the production of seed with suitable 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 government produced only 980 t (Potan 1987). In Indonesia, only 30% of the total area is planted with seeds of improved cultivars (Djauhari et al 1984).
  26. 26. 36 2 GREEN MANURE IN RICE FARMING tropics and subtropics has received attention (Dassou and Kueneman 1984, Kueneman 1983, Opefia et al 1987, Shanmugasundaram 1976, Shanmugasundaram and Poehlman 1988). Successful quality seed production will depend on incorporation of genetically controlled quality traits with desirable agronomic ones. I-lard seeded ness is known to improve seed resistance to detrimental environmental influences (Potts et al 1978). Other characters with similar influences are seed coat thickness (Caviness and Simpson 1974), pod thickness or composition (Hartwig and Edwards 1970), and resistance to seedborne diseases (Wilcox et al 1975). In the past decade, a number of new mungbean and soybean varieties were released to farmers. But seed quality characters have yet to be incorporated into new varieties. Seed categories Genetic improvement must be associated with good seed certification. Farmers should have access to good, relatively affordable seed (Walker 1980). But seed production, inspection, certification, processing, distribution, and marketing vary widely among countries. The steps to produce the various categories of seeds described here apply to mungbean and soybean. Seed multiplication rates vary with the crop. The plant breeder carefully selects for various traits (with adaptability and high yield considered essential) and identifies a line as suitable for release. The identified line is unique in a number of qualitative and quantitative traits. However, certain distinct traits are uniform and stable. These distinguishing characters are consistent and relatively easy to use for a specified region of adaptation. For example, when a new soybean variety is released in the USA, characters such as seed coat color, hilum color, flower color, pubescence color, stem termination, leaf type, USA maturity group classification, pertinent disease resistance or susceptibility, and protein and oil content are described. Foundation seed is produced from the basic breeder seed. Registered and certified seeds are produced by selected farmers. Methods of seed production by the plant breeder, maintainer, seed merchant, and progressive farmer depend on the crop species and on 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, making sure that the variety is pure and free from variations that are not described as part of the variety. Pedigree and basic seed also should be free from weed seeds and extraneous materials. A variant is defined as plants or seeds described as part of the variety, but different from the norm for the variety (Otto 1985). In soybean, natural mutation can cause changes in plant or seed characteristics. Brown and black seed coat mutants are common in yellow seeded soybean; these offtypes should be removed during purification (Fehr 1978).
  27. 27. SEED PRODUCTION AND MANAGEMENT OF MUNGBEAN AND SOYBEAN 363 Mungbean and soybean are self-pollinated, annual species reproduced by normal fertilization. In mungbean, natural outcrossing varies from 0.0 to 13% (Shanmugasundaram and Poehlman 1988). A high level of outcrossing can cause considerable variation in the seed produced. In India, when rnungbean seed was produced, a 1.5-m border was left unharvested between adjacent varieties (Kernick 1961). Considering the large extent of outcrossing in some genotypes, the isolation requirement has been increased to 3 m. Usually, a plant breeder maintains a variety by planting single plant progeny and checking characteristics against the variety's official description. If the rows are uniform, 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 tropical countries, seed production rates vary because of the length of growing seasons and the yield potential of varieties. Pedigree seed is planted on 0.5-1.5 ha to produce 1-3 t soybean and 0.3-1 t rnungbean basic seed. Basic seed is used to produce the subsequent categories of seeds (Shanrnugasundaram 1982). At each stage, care is exercised to remove variants. In countries with official seed certification programs, designated agencies supervise and regulate seed certification. In India, a parastatal national seed corporation coordinates the production of certified seed through a series. of state seed farms that are profit-responsible. They were set up and funded by World Bank (Walker 1980). The All-India Coordinated Research Project on Soybean, in its annual meeting, allocates to each breeder the quantity of seed to be produced. For example, in 1985-86 breeders produced about 92 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 be considered (Nangju et al 1978): field environment, cultural practices, genetic influence, 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 of climate and soils must not be used as excuses for deficiencies in plant genetics, selection procedures, isolation distances, good crop management, and quality control (Walker 1980). Constraints such as photoperiod, temperature, soil properties, and rainfall cannot be controlled by the seed producer (Shanmugasundaram and Tsou 1987). Land preparation, organic or inorganic fertilizer applications, pest and disease control, and weed control and management are factors that can be regulated. A sufficient knowledge pool is available (for a review see Morton et al 1982, Nangju et al 1978, Scott and Aldrich 1970, Shanmugasundaram 1982, Shanmugasundaram and Tsou 1987, Sinclair and Jackobs 1982, Tekrony et al 1978). Although obtaining a high yield is a consideration, the most important criterion is producing good
  28. 28. 36 4 GREEN MANURE IN RICE FARMING quality seed. Since the price of seed is generally higher than the price of grain, extra management inputs are justified. Preharvest factors Seed longevity and field weathering. At the Asian Vegetable Research and Development Center ( AVRDC ) , soybean can be planted in the February, July, and Scptonuberseasons. TbcFebruary crop encounters rain at harvest (Fig.|).The July rainy season crop may be exposed to typhoons. Field weathering of seed is a common problem in both seasons. Therefore, the seed quality of February and July season crops generally is not dependable. The September season CrOp produces the best quality seed (Sb0000ugasuoduranuaod Tsou 1987 ) . The seed quality of rainy season crops, in general, is poor in Indonesia, Thailand, Philippines, Sri Lanka, and ' Nigeria(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 a*c was observed 'in soybean vo o ( Wien and Kucocnouo1981). Freshly harvested seeds of /[}S 2, a pure line from an Indonesian introduction; [`/ from India; and /[}S 29 from AVRDC maintained about 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 2-3 mo (Fig. 2). Small-seeded varieties from Indonesia and black seed coat varieties deteriorate more slowly than large-seeded varieties. However, reports on the role of large and small seeds in seed longevity, germination, emergence, and yields have Precipitation (mm) 1700 Temperature (OC) 40 1 600 30 500 400 20 300 200 10 100 0 J F M A M J J A S 0 N D 0 Month I. Maximum and minimum temperature and rainfall pattern at AVR DC in 1984 and time of planting and harvest.
  29. 29. SEED PRODUCTION AND MANAGEMENT OF MUNGBEAN AND SOYBEAN 365 been contradictory (Edwards and Hartwig 1971, Fontes and Ohlrogge 1972, Green et al 1965, Johnson and Luedders 1974, Ndunguru and Summerfield 1975). Some changes associated with seed deterioration are reduced protein synthesis, reduced ability to utilize labeled glucose, reduced respiration, and increased respiration quotient (A. Knapp, pers. comm.). Although small seeds are associated with better seed 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 equally satisfactory in the laboratory test (Heydecker 1972). Loss of seed vigor due to weathering precedes loss of seed viability. Assessing seed vigor is problematic for seedmen (Kuenernan 1982). The concept of seed vigor and its importance to seed production were described by Heydecker (1972) and Perry (1978). A modified accelerated aging and hot water stress test were used to screen for seed longevity and vigor. In the accelerated aging stress test, seeds are kept at 42 °C and 100% relative humidity (RH) for 48 h, followed by a laboratory germination test (Byrd and Delouche 1971). To distinguish cultivars with good and pOOr seed storability, Wien and Kueneman (1981) used a modified accelerated aging stress technique. After pods dried, 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 2 AGS 29 V AGS 66 V AGS 129 0 Pb-l(check) Bragg (check) 40 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 ambient temperature. Bangladesh, 1985.
  30. 30. 36 6 GREEN MANURE IN RICE FARMING Hot water pregermination stress includes soaking seeds for 70 s in 75 'C water and rinsing in tap water prior to determining germination or emergence (Kueneman ( g 82). Kueocooan(] q 83 ) 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 of the maternal plant genome on seed longevity. The pooled F 2 variances were larger than pooled parental variances, which indicated the influence of the genotypes. Differences between reciprocals of the F 2 seed, although relatively small compared to those between F, reciprocals, were significant, indicating that cytoplasmic gene action 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 delayed one 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 genotypes PI 205912, P1 205907, [»[ 341249, PI 279088, and {/1 219653 could be used for breeding soybean with resistance to field weathering and to seed deterioration in storage. 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 roidMay.Hovvovez ` early maturity is not a dependable alternative. In some years, rains may 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 harvested October-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. Genotype Origin I NDO 153 Indonesia IPA DO 131 I P4 DO 243P Indonesia Indonesia Indonesia 1 WOD226 104 DO 255 Indonesia INDO 173A Fort Lamy Lee A Biloxi 3 Indonesia USA USA China AVRDC 8457 Taiwan 1 00'noed wt (g) Seed color 9.7 10.2 8.9 9.3 10.1 Black Black Black Black Black 1 0.8 Black 10.5 9.0 10.5 6.1 Black Black Black Black Source: O0000uond Kueneman 1984. Nonimbibino seed after 1 h soaking in water. humidity. bm Hard a seed After incubator weathering After ambient storageb 36.0 24.6 17.2 27.2 54.2 87 35.4 92 42.9 46.2 90 80 30.6 52.6 32.6 32.9 91 81 46.6 62.0 37.2 56.2 58.5 50.4 58.7 80 88 71 77 64.0 Stored forO mo at 25 0 C and 50 to 95% relative
  31. 31. SEED PRODUCTION AND MANAGEMENT OF MUNGBEAN AND SOYBEAN 367 crops comes from the second upland dry season crop. Seed for the second dry season crop comes from the first dry season crop. Only the grain of the rainy season crop is used ( Fig. 3). Similar seed production strategies are used in other countries ( Potan 1987,Sncnarno 1987). Water management. Water management is closely associated with field weathering in both soybean and rnungbcaooeed production ( Huck and Davis 1976, Morton et al 1982). Soybean that undergoes alternate wetting and drying in the field has poor seed quality caused by rapid differential absorption of water by localized tissues in the seed coat ( Moore 1971, 1972). Plasmolysis and deplummooysia at external and internal seed injuries i moisture also has been observed in 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 different stages of seed development can result in (Min ` z* / 1957). Damage caused by on-and-off excess 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 good quality 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 Local VMS variety Dry season 1 Dry season 2 Local variety 3. Flow of soybean seed between locations in different seasons in East Java, Indonesia (source: personal discussions with farmers, extension staff, and researchers ) . The arrows show seed flow.
  32. 32. 36 8 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 Java for planting. Distance, mode of transportation, type of packing material, and handling are important considerations in seed quality. Pest management. Because seed is a high value crop, seed quality is an i mportant consideration. In seed production, weed, insect, and disease control using recommended management practices is mandatory. Weeds can compete with a crop and restrict the use of nutrients, reducing crop quality. Weeds can also harbor insect vectors that may transmit various virus diseases and can serve as hosts for various fungal and bacterial diseases. Many leguminous weeds are hosts for soybean rust Phakopsora pachyrhizi and can serve as a reservoir of initial inoculum to create epidemics on soybean. If the field is weedy, the seeds can be contaminated with weed seeds during harvest (Nangju et al 1978). The stink bug Nezara viridu/a in soybean and various pod borers in rnungbean and soybean can reduce seed quality (Morton et al 1982, Todd 1982). The beanfly A/felanagronomyza sp. and others can reduce seedling vigor and impair seed quality. It is imperative to monitor insect pest incidence and adopt appropriate, timely control measures. Christensen (1972) tested thousands of soybean and seed samples over 20 yr to determine storage fungi invasion-of seeds prior to harvest. He concluded that there is no significant invasion of seeds by storage fungi. Fungal pathogens that can cause a reduction in seed quality in soybean are pod and 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, chemical control of these diseases is important. Among the soybean viruses, soybean mosaic virus (SMV), tobacco ringspot virus (TRSV), and tobacco streak virus (TSV) may be important (Sinclair and Shurtleff 1975). In mungbean, yellow mosaic virus (YMV) is the most important virus disease. Vector control and planting resistant varieties are the only means of controlling virus diseases. Postharvest factors A seed begins its existence well before it is harvested. Preharvest conditions can cause 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 excessive moisture or too low moisture content can also damage quality. If the crop has to be harvested before full maturity, but after physiological maturity, it should be dried slowly under moderate temperature. Slow drying prevents shriveling due to rapid loss of moisture. After physiological maturity, seeds of both soybean and mungbean may begin to sprout during the rainy season while the plants are still in the field.
  33. 33. SEED PRODUCTION AND MANAGEMENT OF MUNGBEAN AND SOYBEAN 369 Under those circumstances, it is better to harvest at the onset of rain and dry the plants in a well-ventilated area. They can be air-dried slowly to enable threshing later. Threshing and cleaning High cylinder speeds of combines or threshers will result in multiple fractures and deep-seated bruises, especially in large-seeded soybean or mungbean and in seeds with lower moisture content (Moore 1957, 1972; Roberts 1972a). A 700 rpm cylinder speed is better than 1155 rpm. Soybean seeds impacted at 12-16% seed moisture germinated satisfactorily; those impacted at 8-10% and 18-20% moisture germinated poorly (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 small tractors. Such harsh treatment can result in mutilated seeds. Studies at IITA showed that 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 seed moisture 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 should be examined for purity and variants should be removed. Seeds with mottling due to SMV should be removed. Testing for viability and longevity A number of factors can influence seed quality and viability during production. Poor seed with low viability will be even poorer after storage. Therefore, seed lots need to be examined before storage. A good-looking seed may not necessarily be good quality. Seed viability is usually measured when the seed is planted, but it is also measured for industrial purposes (MacKay 1978). Incubator germination, field emergence, tetrazolium, seedling growth rates, and seed leachates are some of the tests 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 postharvest factors can influence seed longevity. These tests of seed longevity have been proposed: 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 storage Factors to consider in storing seeds until planting are initial seed moisture content, genotype, temperature, RH, the container in which the seed is packed, and the method of packing. At AVRDC, seeds are sun- or air-dried to 8% moisture content for 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). With 8.1-9.4% seed moisture content, soybean seed can be stored at 10 ° C for 10 yr; at 13%
  34. 34. 37 0 GREEN MANURE IN RICE FARMING Table 4, Equilibrium moisture content of soybean at 25 0 C at 30-95% relative humidity (RH) (Roberts and Roberts 1972). Equilibrium moisture content at given RH 1 0% 4.3 30% 45% 60% 75% 6,5 7.4 9.3 1 3.1 95% 18.8 moisture content, it can be stored for 3 yr. At 20-30 °C, seed with 13-18% moisture content will remain viable for less than a year (Toole and Toole 1946). Under tropical conditions, high initial quality soybean seeds at 9-9.5% moisture content can be safely stored 9 mo at 20-25 °C and 50-60% RH (Gregg 1982). Most AVRDC breeding materials with good initial seed quality and 9-10% moisture content are stored at 20-24 °C and 55-60% RH. The majority of the entries stored under these conditions retained more than 80% viability for at least 2 yr. Similar storage conditions are suitable for mungbean. If storage conditions have a higher RH, there is no need to dry the seed to less than equilibrium moisture content. At 45% RH or lower, seed should be dried to 7.4% moisture content or lower. At 60% RH, drying the seed to 9% moisture will suffice. Soybean seed moisture content at 25 °C with different relative humidity levels are given in Table 4. The usual rule of thumb for storage conditions for the short term is percent RH and 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 10 0.06451 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, all storage fungi are completely inactive (Roberts 1972a). Below 60% RH, storage insects are inactive. Because rnungbean weevil is a serious storage pest, it is .i mportant to maintain RH below 60% and seed moisture content below 8% (Roberts 1972a). The minimum germination required for seed certification varies among countries. 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 in India is 75% (Agrawal 1980). Under ambient conditions, mungbean appears to be storable longer than soybean (Table 5). Traditional mungbean varieties appear to have a high proportion of hard seeds, but hard seededness decrease with age in storage. Mungbean seed loses hard seededness with a year (Pathwardhan 1927). During domestication, the hard seededness character was selected out. It appears probable that this trait in mungbean can be used in breeding for good seed quality (B. C. Irnrie, pers. comm.). Soon after harvest, hard-seeded rnungbean germination is low, but it improves with storage (Rajasekara Mudaliar and
  35. 35. SEED PRODUCTION AND MANAGEMENT OF MUNGBEAN AND SOYBEAN 371 Table 5. Germination of quality seed tested after different durations in storage at ambient con- ditions in Delhi, India (Agra al 1980). Germination (%) Crop 0 Mungbean cultivar P. S.-16 . 99 Soybean cultivar Bragg 94 3 mo 6 mo 12 mo 18 mo 24 mo 99 93 99 81 99 43 98 14 36 mo 0 0 37 mo 98 0 Table 6. Germination of soybean seed stored in different containers at amieient room temperature and cold room for different durations in Sri Lanka ( Aruinandhy 1987). Storage period ( mo.) 0 3 6 Germination (%) Storage condition Gunny bag Ambient Cold Ambient Cold AmbientCold 90 90 80 88 2 79 Polyethylene bag 90 90 81 80 70 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 a variety 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 using steel 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 are common in Taiwan. Sealed polyethylene bags kept in a shaded area can safely store seed for 6-9 mo (Table 6). Vaporproof packages for storage protect seed from drastic fluctuations 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 off mungbean weevil, such facilities are unavailable in developing countries in the tropics. Asian villagers traditionally have used peanut oil to protect pulse grains against storage insects. Results at AVRDC suggest that peanut oil or soybean oil at 2-3 ml/ kg of seed can effectively suppress weevil reproduction in stored mungbean for 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 is vulnerable to damage by biotic factors. Almond moth Ephestia mute/1a can develop
  36. 36. 37 2 GREEN MANURE IN RICE FARMING 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 produce typical antibiotic symptoms (Sirisingh and Kogan 1982). Future of seed production Rapid advances in innovative breeding concepts and procedures will surely modify concepts 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 for plant type. The working philosophy of the future will emphasize performance over uniformity. In such cases, seed certification probably should monitor seed quality rather 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, and store good quality seed for small farmers is needed. The mechanisms involved in protecting against insects using home remedies such as peanut oil need further exploration. Research also should focus on the reasons for good seed quality with small seeds and black seeds, with or without hard seededness. The role of the environment at different stages of seed development and its relevance to seed deterioration deserve further study. Because farmers are interested in storing seed at most for 6-9 coo, research with that objective should be distinguished from commercial concerns for longer term storage. There is growing awareness, even in developing countries, of the need to obtain quality seed for planting. Farmers consider it an important single investment that is a prerequisite-if all other management inputs are to pay off. But both government and private industry are unable to meet the demand or provide good quality seed. The price of certified seed is almost double the price of regular seed ( in Thailand, regular p seed costs US$1.40/kg; certified seed costs $3.0/k )(Potao 1987). However, the government offers subsidies or other means of obtaining quality seed. Governments also should encourage the private seed industry to meet local demand without unduly exploiting the farmers.
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