Vigna trilobata (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Vigna trilobata (L.) Verdc.

Protologue: Taxon 17: 172 (1968).

Family: Leguminosae - Papilionoideae

Chromosome number: 2n= 22

Synonyms

• Dolichos trilobatus L. (1767),
• Phaseolus trilobatus (L.) Schreber (1770),
• P. trilobus auct., non L. (1753).

Vernacular names

• Phillipesara (En)
• Indonesia: kacang kate.

Origin and geographic distribution

V. trilobata occurs from India and Sri Lanka to Malesia and Taiwan. In Malesia, it is reported from Indonesia, Malaysia and Papua New Guinea. Introductions have been made into Africa, Madagascar and Peru. It is cultivated in the Sudan.

Uses

V. trilobata is grown as a green manure and fodder crop mainly in India, Pakistan and the Sudan. The seeds are eaten only by poor people in India.

Properties

The approximate nitrogen yield per ha of the components of a crop of V. trilobata is: roots 5-16 kg, nodules 2-4 kg, leaves 84-97 kg, stems 53-94 kg, pods 14-35 kg. A trial in Queensland (Australia) comparing the nitrogen mineralization rates of 6 legume species found that the leaves and young stems of V. trilobata contained per 100 g dry matter: nitrogen 2.3 g, lignin 7.7 g and polyphenols 1.9 g. Stems and leaves incorporated in the soil decomposed fairly rapidly: two weeks after incorporation, 13% of the added N had been mineralized, rising to 27% after 6 weeks, and 42% after 12 weeks. The mineralization rate of V. trilobata was faster than that of leucaena (Leucaena leucocephala (Lamk) de Wit), but slower than lucerne (Medicago sativa L.)

Botany

• Annual or perennial, prostrate and trailing herb, up to 2 m long; branches striate, glabrous or pubescent.
• Leaves trifoliolate; stipules oblong, peltate, sometimes spurred, 4-15(-20) mm long; petiole 3.7-7.5(-11) cm long; petiolule up to 2.5 cm long; stipels small; leaflets deeply 3-lobed, 1-5 cm × 0.5-4 cm; lobes oblong-obtuse or subacute, central lobe largest, glabrous to subglabrous.
• Inflorescence a few-flowered, axillary raceme, 3-25 cm long; peduncle 8-22 cm long, bearing small, pale yellow flowers at the top; pedicel 2-3 mm long; bracts caducous; bracteoles linear-ovate, up to 4 mm long, attached below the calyx.
• Calyx campanulate, 2.5 mm long, glabrous, bearing 5 teeth of which the 2 upper ones are united and the lowest one is longest; corolla yellow, 5.0-6.5(-8) mm long, standard subcircular, emarginate, auriculate, wings obovate, with linear auricle, keel asymmetrical, narrow, long, obtuse, twisted in a complex spiral; stamens 10, upper one free, others united; style spirally twisted, bearded below the oblique stigma.
• Pod curved, subcylindrical, 2.5-5 cm × 3-4 mm, glabrous to sparingly pubescent, 6-12-seeded.
• Seed ellipsoid, 3 mm × 2 mm, brown.

In Pakistan, V. trilobata flowers in October. It nodulates and fixes atmospheric nitrogen. Nodule formation starts 10-14 days after germination, while nitrogen fixation can be detected from 17-23 days after germination. The number of nodules per plant at maximum plant weight ranges between 41-63. Nodule weight constitutes 1.3% of plant weight. Nodules are diffuse, lobed, of medium size (2-4 mm in diameter), and occur mainly on the main root, with smaller ones on lateral roots; they are easily shed.

V. lobata greatly resembles V. radiata (L.) R. Wilczek var. sublobata (Roxb.) Verdc. (small form of mung bean, occurring in the same region), but can be distinguished by its longer stipules and bracteoles, its longer peduncles, and its smaller flowers, fruits and seeds.

Ecology

V. trilobata thrives in a wide range of conditions, especially near forest edges and on waste land. In India and Indo-China, it flourishes from the plains up to an altitude of 2100 m. Its drought tolerance is outstanding. From central Queensland (Australia), an accession has been reported to be particularly drought hardy, but it shatters its seed readily and is killed by frost. In northern Queensland, a selection from the Sudan showed good persistence, regeneration and spread in a 4-year experiment on heavy, cracking clay soils.

Agronomy

Propagation is usually by seed, which needs scarification to improve germination. Inoculation with appropriate Rhizobium prior to sowing improves early growth in new locations. Planting density varies according to the use. Farmers in the Sudan broadcast 30 kg/ha when the crop is grown for fodder. The amount is increased to 60 kg/ha when it is grown as a green manure and is ploughed into lines to control weeds. A study on atmospheric nitrogen fixation of various forage legumes and their rotational effect on the yield of subsequent cotton crops in the Gezira Research Station, the Sudan, revealed that forage yield of V. trilobata was higher than the yield of butterfly pea (Clitoria ternatea L.), lablab (Lablab purpureus (L.) Sweet), groundnut (Arachis hypogaea L.), mung bean (Vigna radiata (L.) Wilczek), cowpea (Vigna unguiculata (L.) Walp. cv. group Unguiculata), and soya bean (Glycine max (L.) Merrill). The fresh and dry weight yields of V. trilobata were approximately 30-48 t/ha and 7-19 t/ha, respectively. The total nitrogen yield was 165-235 kg/ha. However, the V. trilobata forage-cotton rotation resulted only in a slight but non-significant increase in soil nitrogen and was not large enough to appreciably affect the nitrogen response of cotton yield. Thus V. trilobata, grown for fodder and cut and removed leaves, limited amounts of fixed atmospheric nitrogen to influence rotational effedts. If grown as a green manure the situation will be different, but research data are not available. Several strains of Rhizobium were greenhouse-tested on V. trilobata to determine their effectiveness in a soil of pH 6.3 that was N-deficient but otherwise fertile. Dry matter production and nitrogen yield of plants that received fertilizer N exceeded that from any of the unfertilized inoculated plants. In an acid soil, almost all Rhizobium strains tested nodulated V. trilobata. Liming the acid soil reduced nodulation and plant growth in all treatments.

In Gezira, the Sudan, V. trilobata was tested in an intercropping experiment with Sudan grass (Sorghum x drummondii (Steud.) Millsp. & Chase) on heavy, alkaline clay soils. The highest forage and crude protein yield was obtained at a sowing rate of 15 kg/ha (75% of the seed rate for a sole crop) of V. trilobata and 15 kg/ha (25%) of Sudan grass. The dry forage yield per ha was 1.5 t of V. trilobata and 1.4 t of Sudan grass.

Genetic resources and breeding

V. trilobata is included in several germplasm collections of Vigna spp., e.g. at the Asian Vegetable Research and Development Center (AVRDC), Shanhua, Taiwan and the Southern Regional Plant Introduction Center, Griffin, Georgia, United States. There are no known breeding programmes on V. trilobata.

Prospects

With its ability to thrive under drought and with a rapid rate of N mineralization, V. trilobata can be an excellent pioneer green manure crop for semi-arid regions. Being high-yielding and able to compete vigorously with associated weeds under rainfed conditions, it is also a promising pasture legume.

Literature

• Cameron, D.G. & Mullally, J.D., 1969. The preliminary evaluation of leguminous plants for pasture and forage in sub-coastal central Queensland 1962-69. Australian Plant Introduction Review 6: 29-54.
• Fox, R.H., Myers, R.J.K. & Vallis, I., 1990. The nitrogen mineralization rate of legume residues in soil as influenced by their polyphenol, lignin, and nitrogen contents. Plant and Soil 129: 251-259.
• Ibrahim, A.E.S., 1995. Summer forage yield of irrigated Sudan grass (Sorghum sudanense (Piper) Stapf) and phillipesara (Vigna trilobata Verdc.) in monoculture and in mixtures. Tropical Science 35: 1-8.
• Musa, M.M. & Burhan, H.O., 1974. The relative performance of forage legumes as rotational crops in the Gezira. Experimental Agriculture 10: 131-140.
• Nguyên Van Thuân, 1979. Leguminosae - Papilionoideae, Phaseoleae. In: Vidal, J.E. & Vidal, Y. (Editors): Flore du Cambodge, du Laos et du Viêtnam. Vol. 17. Muséum National d'Histoire Naturelle, Laboratoire de Phanérogamie, Paris, France. p. 199.
• Skerman, P.J., Cameron, D.G. & Riveros, F., 1988. Tropical forage legumes. 2nd ed. FAO Plant Production and Protection Series No 2. Food and Agriculture Organization of the United Nations, Rome, Italy. pp. 476-477.
• Zaroug, M.G. & Munns, D.N., 1980. Screening strains of rhizobium for the tropical legumes Clitoria ternatea and Vigna trilobata in soils of different pH. Tropical Grasslands 14: 28-33.

Authors

• K.C. Wong