Winged Bean in Organic Farming System: A Boon for Small farmers
Authors: M. Bilashini Devi*, H.D. Talang, H. Rymbai and A.K. Jha
Scientist, ICAR Research Complex for NEH Region, Umiam-793103, Meghalaya

India is the second most populous country in the world. With the increasing population, the cultivable land resource is shrinking day to day. To meet the food, fibre, fuel, fodder and other needs of the growing population, the productivity of agricultural land and soil health needs to be improved. Green Revolution in the post independence era has shown path to developing countries for self-sufficiency in food but sustaining agricultural production against the finite natural resource base demands has shifted from the “resource degrading” chemical agriculture to a “resource protective” biological or organic agriculture.Sustainable agriculture is necessary to attain the goal of sustainable development. According to the Food and Agriculture Organization (FAO), sustainable agriculture is defined as the successful management of resources for agriculture to satisfy changing human needs while maintaining or enhancing the quality of environment and conserving natural resources. Organic farming is one of the several approaches found to meet the objectives of sustainable agriculture. Some of the techniques used in organic farming are inter-cropping, mulching and integration of crops and livestock. Organic vegetable cultivation offers one of the most sustainable farming systems with recurring benefits to not only long-term soil health but provides a lasting stability in production by importing better resistance against various biotic and abiotic stresses. Organic vegetables fetch a premium price of 10%- 50% over conventional products. In this context, crop diversification with adoption of hardy underutilized vegetable crops which are less affected by biotic and abiotic stresses can be a promise for the farming community. Winged bean (Psophocarpus tetragonolobus), an underutilized legume has gained much attentionin recent years because ofits fast growth, high yield, tolerant to biotic and abiotic stresses and nutritional quality.It is a multipurpose crop in which all theparts except the stem are edible, palatable andnutritious. In India it is primarily confined to the humid sub-tropical parts of northeastern region i.e., Tripura, Manipur, Mizoram and adjoining areas. As compared to these hill states, it is less common in Bengal plains, and is of sporadic occurrence in parts of Western Ghats.The beans are used as a vegetable but the other parts (leaves, flowers and tuberous roots) can also be eaten. The young leaves can be used as a leafy vegetable, similar to spinach. The roots, which have a nutty flavour, can be used like a potato and are much higher in protein. The dried beans are similar to soybeans in both use and nutritional content. Infact, this crop being a climber, takes less land to produce the same harvest as that of soyabean. It prefers to grow in the humid tropics. Every part of the wing bean is nutritious and is so also known as multipurpose bean. Wing beans have the highest calcium content among all legumes and are also an excellent source of protein, minerals, vitamins (especially A and C), iron and enzymes. Yet this crop is cultivated primarily for home consumption and not on commercial scale.

General description of the plant: Winged bean is a perennial plant with indeterminate vine. The colour of the pod ranges from green to purple. The underground part is the tuberous root. Tuber formation is environment specific. Under certain conditions there is no tuber formation while under other environmental conditions, some varieties form tuber exclusively with low grain yield. The flowers are borne in cluster and colour of the corolla ranges from white, blue to purple. The pod can be either straight or slightly curved and about 10-50 cm long. They characteristically have four prominent longitudinal wings corresponding to the four corners of the pod with curved indentations of the border of the wings. The seeds are either flat or round with colour ranging from deep purple through tan brown to almost white.

Nutritive value: Winged bean has exceptionally high nutritive value. The mature seeds contain 29 to 37 % protein and 15-18% edible oil. It has fairly good amounts of phosphorus (0.2-12 mg/100g) and iron (26-60 mg/100g)). It is also a rich source of calcium (53-236 mg per 100g). Essential amino acid composition of winged bean is very similar to that of soybean (Kadam and Salunkhe, 1984). The seeds are rich in antioxidant and tocopherol which improve human utilization of vitamin A.

Soil and Climatic Requirement: Winged bean is a hardy legume crop and adapt well to soil types ranging from sandy to clay having pH 4.5 to 8.5. For optimum growth soil should be rich in nutrient with good drainage. The crop can be grown in a wide range of altitude from sea level to 2400 m in optimum conditions. The diversity of altitudes tolerated by winged bean indicates that it can adapt to a wide range of temperature, tolerating high temperature without major problem. However, plants produce flowers during short days and between 18 0 and 320 C temperature.

Spacing: The planting should be done at a spacing of 90 × 90 cm in case of tall varieties and 45 × 45 cm incase of dwarf variety.

Cultural operation: Since the crop is not grown on commercial scale the production technology for this crop is not well developed and standardized. Staking is important interculture operation for vigorous growth and easy harvest of the aerial parts of the plant. For getting economic yield staking can be done with easily available materials like bamboo poles. A fertilizer dose of 20 kg N, 100 kg P2O5 and 40 kg K2O per ha should be applied before sowing. At the time of flowering 20 kg N per ha should be apply. Hoeing and weeding should be done during the initial stage of crop growth.

Harvesting and yield: The photoperiod and date of planting affect the vegetative period and hence harvesting of the crop.The crop can be harvested at different stage depending on whether the green pod or the dried beans are to be used. The tender pods are ready for harvesting within 2-3 months of planting. Continual harvesting of young pod lengthens the period of flowering. Seeds or dried bean are ready for harvesting at 5-6 months after planting. Tuberous root are ready for harvesting at 4-5 months after planting. The yield of green pods and tuber is 45-96 q and 55-60 q per ha. A well managed crop produces 15 q/ha grain yield.

Winged bean and organic farming system: This crop can be grown successfully in association with other crops or as a part of organic farming system. Being leguminous crop it can fix atmospheric nitrogen and can occupies a secondary position or as a filler crop in organic farming system to improve the soil health. Even though winged bean is usually grown in association with other crops, its commercial production may require its cultivation in monoculture.

Cover crop: Winged bean can be used as a cover crop for organic farming system. Its potential as a cover crop to prevent soil erosion and weed control have been studied and reported by many researchers. The rate of covering over the soil by this crop is reported to be 0.6 m2 per m2 in the inter-row area 12 weeks after sowing which increased with almost completely covering being achieved 12 to 32 weeks after sowing ( Kitou et al., 2010). Therefore, winged bean has a great potential to be used as a cover crop in organic farming system to prevent soil erosion and control weeds.

Green manure: Green manures are plants that are grown mainly for the benefit of the soil. They can be grown either as part of a rotation or in an intercropping system to build soil fertility. The appropriate management and efficient utilization of crop residues are important for the proper amendment of soil quality and crop productivity under organic farming system. Being legume, winged bean has nodules on its roots which contain bacteria. These bacteria take nitrogen from the air. This is known as atmospheric nitrogen fixation. The plant uses this to grow and when the legume is dug into the soil, the extra nitrogen is made available to the next crop. The use of this legume has been proven to be commendable in terms of its positive effects. Winged bean is a traditional vegetable cultivated in marginal land and there are ample opportunities to adapt this crop in crop rotation system. It has been revealed by scientific study that rice after winged bean without fertilizer can produce rice yield equivalent to that of rice after fallow with N fertilizer at rates of 8 g N m−2. The harvest index value for rice after winged bean crop rotation indicated a positive response for rice production without deteriorating soil fertility (Rahman et al., 2014).

Mixed Cropping/Intercropping: Intercropping or mixed cropping culture provides sustainable farming systems with enhanced land and energy use.Winged bean is a readily nodulated tropical legume with high food value. Little is known concerning the intercropping potential of winged bean with other crops or the effects of nitrogen (N) levels on intercrop system including winged bean. A study involving winged bean and maize intercropping indicated that nitrogen stress did not cause decreased growth of maize when grown with winged bean. This may be due to an allelopathic effect of winged bean on maize (Hikam et al., 1991).

Conclusion: Winged bean has good potential within organic farming system. Realization of this potential depends upon timely establishment, favorable environmental conditions, and adequate fertility. As discussed in this article, winged bean can be included in organic farming system in various manner-as cover crop, crop rotation, mixed cropping and even grown in monoculture but farmer innovation is needed for integrating winged bean in specific organic farming system.

References :

Rahman MM, Islam AM, Azirun SM and Boyce AN. 2014.Tropical Legume Crop Rotation and Nitrogen Fertilizer Effects on Agronomic and Nitrogen Efficiency of Rice.The Scientific World Journal pp11.

Hikam S, Mackown CT, Poneleit CG and Hildebrand DF. 1991. Growth and nitrogen accumulation in maize and winged bean as affected by nitrogen level and intercropping. Annals of Botany 68: 17-22

Kitou M, Anugroho F, Yamashita T and Kobashigawa N. 2010. Potential utilization of winged bean as a cover crop. Research for Tropical Agriculture 3:1-5

Kadam SS, Salunkhe DK. 1984. Winged bean in human nutrition. Critical Review in Food Science and Nutrition 21(1): 1-40

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