Psophocarpus scandens (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Psophocarpus scandens (Endl.) Verdc.

Protologue: Taxon 17: 539 (1968).

Family: Leguminosae - Papilionoideae

Chromosome number: 2n= 18

Synonyms

• Psophocarpus palustris auct., non Desv. (1826),
• P. longepedunculatus Hassk. (1842),
• Mucuna comorensis Vatke (1878).

Vernacular names

• Psophocarpus (En)
• Indonesia: kecipir monyet (Javanese), jaat monyet (Sundanese).

Origin and geographic distribution

P. scandens is a native of tropical Africa and widely distributed from Cameroon to Angola and from Tanzania to Mozambique and Madagascar. It is cultivated in Zaire, Brazil, the West Indies, India, Sri Lanka, Burma (Myanmar), Vietnam and Indonesia. It has naturalized in Brazil.

Uses

P. scandens is grown as a cover crop and green manure in Central Africa, Asia and tropical parts of the New World. In Indonesia, it is grown as a cover crop in rubber and oil-palm plantations, while the leaves are used as a fodder in a mix with grasses and other legumes. In West Africa, the pods are used as a famine food. In Zaire, the primary use is as a vegetable; in the market of Kinshasa, Zaire, bundles of young shoots and pods are sold and eaten after boiling in water or milk. The pods are given to nursing mothers to stimulate milk production. In Zaire, it is also grown as a fodder for livestock and for fish raised in ponds. In traditional medicine, bruised leaves are applied as a compress for open cuts, wounds, and haemorrhoids. Fresh and dried leaves are consumed after boiling or as a tea to relieve the discomfort of stomach inflammations. In Zaire, P. scandens is also a source of tannin.

Properties

In Indonesia, immature pods of P. scandens contain per 100 g: 88-95 g water and 1.2-3.1 g protein. In Zaire, foliar analyses indicated per 100 g dry matter: protein 31-39 g, lipids 12 g, carbohydrates 32 g, P 0.35 g, K 1.2 g, Ca 2.1-3.1 g, Mg 0.4-1.4 g, S 0.5 g; analyses of pods indicated per 100 g dry matter: protein 7.1-27.9 g, lipids 2.7 g, carbohydrates 56.4 g, P 0.1-0.5 g, Ca 0.5-2.3 g, Mg 0.1-1.5 g.

Analyses of the leaves in Sumatra (Indonesia) indicated per 100 g dry matter: C 25.9 g, N 4.5 g, P 0.26 g, K 1.0 g, Ca 1.3 g, Mg 0.3 g; analysis of the stems indicated per 100 g dry matter: C 27.2 g, N 1.85 g, P 0.14 g, K 1.6 g, Ca 1.1 g, Mg 0.3 g; analysis of the roots: C 27.5-30.6 g, N 2.3-2.4 g, P 0.2 g, K 0.8-1.0 g, Ca 1.0-1.3 g, and Mg 0.2 g. The protein content of the seed is higher than in other legumes, except for groundnut, soya bean and winged bean.

P. scandens produces a nectar that is rich in sucrose from glands in the flowers and on the pedicels. The weight of 1000 seeds is 90-100 g.

Description

• Perennial climbing or twining herb, 1-6 m long, with a tuberous main root and glabrous or sparsely hairy to glabrous stems.
• Leaves trifoliolate; stipules oblong-lanceolate, persistent, spurred, 0.8-1.7 cm long including the spur; petiole 5-18 cm long; rachis 0.8-5 cm long; petiolule 3-6 mm long; leaflets ovate-rhomboid to broadly rounded, 2.5-12 cm × 1.8-10 cm, acute or acuminate at the apex, cuneate to truncate at the base, occasionally 3-lobed, glabrous or glabrescent on both surfaces, margin often ciliate.
• Inflorescence a several to many-flowered pseudo-raceme; peduncle 3-40 cm long; rachis 5-12 cm long, pubescent; pedicel 2-6 mm long, pubescent; bracts semi-caducous, ovate-lanceolate or elliptical, 5-11 mm × 2-4 mm; bracteoles persistent, ovate-oblong or elliptical, 7-14 mm × 5-8 mm, nearly as long as or longer than the calyx, glabrous or glabrescent.
• Calyx glabrous or puberulous, tube 5-7 mm long, lower lip with median triangular lobe 2.5-3.5 mm long, and 2 lateral very broadly deltoid lobes 1.5 mm long, 2 upper lobes fused into an emarginate lip; standard pale-blue or mauve, obovate-oblong, 1.5-2.1 cm × 1.2-1.5 cm, emarginate; wings blue-lilac or with blue or violet margin; keel 5.5-7 mm wide, blue-lilac, whitish or with blue or violet margin, not prominently beaked.
• Fruit an oblong pod, square in cross-section, 3.5-8 cm × 6-7 mm, 4-8-seeded, glabrous, prominently 4-winged, wings 2.5-6.5 mm wide, slightly serrate, often striate, sometimes puberulous along the margins.
• Seed oblong or sub-cylindrical, (5-)6-7.5 mm × (3.5-)5-6 mm, blackish-purple, with minute granular, orange, easily removable tomentum or brown silky hairs on the edges.
• Seedling with epigeal germination, first leaves blotched.

Growth and development

After germination, initial growth is slow; once well established, growth is vigorous. When grown mixed with other cover crops, P. scandens may overgrow and suppress the companion crops within a year, remaining as the sole cover crop after two years. Planted as a ground cover, the ends of the shoots rise and twine. In dense stands, they may find mutual support and intertwine, forming loose strands or conical heaps rising well above the rest of the cover crop. These heaps become top-heavy, bend and are then taken up in the cover crop. The sprouts of new shoots may form similar heaps which intermingle with the older ones forming an airy, but closed soil cover. Branches may root at the nodes where they touch the soil. Nodules with abundant leghaemoglobin may form on these adventitious roots.

In Sumatra, flowering starts about 115 days after sowing, taking place from January to March, while fruits mature from April to May. Some further flowering and fruiting may take place from October to December. In Hawaii, flowers are initiated during late October and early November and flowering continues until mid-February to early March. Seed can be collected from plants any time of the year since pod shattering is low in humid locations. In Bogor (Indonesia), bumble bees (Xylocopa confusa) have been observed to visit open flowers. Only the lower flowers in an inflorescence usually develop into fruits; the upper flower buds abort unless the lower ones are damaged.

Other botanical information

P. scandens used to be included in P. palustris Desv. and is still often confounded with it. Most agronomic information on P. palustris should be attributed to P. scandens. P. palustris is restricted to Africa, occurring from Senegal to the Sudan. It differs from P. scandens in the following characteristics: is a pubescent herb; leaflets ovate-elliptical, never 3-lobed, terminal leaflet broadest in the middle, with cordate base; bracteole 4.5-6.5 mm × 3-5 mm, approximately half the length of the calyx; keel beaked at apex, 6.5-9 mm wide; pod 2.3-5.5 cm long, 3-5-seeded. P. scandens is sparsely pubescent to glabrous; leaves ovate, occasionally 3-lobed, terminal leaflet broadest near the base, base more truncate; bracteole 7-14 mm × 5-8 mm, equal in length or longer than the calyx; keel not prominently beaked, 5.5-7 mm wide; pod 3.5-8 cm long, 4-8-seeded. P. palustris also differs from P. scandens in having a chromosome number of 2 n = 22. At the edges of their natural areas of distribution some introgression occurs. A few specimens show bracteole characteristics of P. palustris and leaflet characteristics of P. scandens.

Ecology

In Zaire, P. scandens grows well in locations with average annual rainfall of 1200-1800 mm, and mean annual temperature of 25 °C. It thrives in full sunlight, but tolerates some shade. It prefers damp sites near lakes, marshes, ponds, rivers and streams, but also occurs in drier environments. It is found in disturbed habitats such as grassland, fallow land, riverine thickets, savanna edges, in periodically flooded forest, swamp forest edges, semi-deciduous forest and secondary forest up to 950 m altitude. It grows well on heavy, swamp soils. In East Java, it is grown on gley soils of low humus content, with a loamy-clay texture.

Propagation and planting

P. scandens is propagated by seed, but vegetative propagation by cuttings or tuberous main roots is also possible. Stem and root cuttings may be successful, if rainfall is sufficient, but they require much labour. After harvesting, the germination rate of the seed declines rapidly; only 15% of seeds stored in gunny-bags will germinate after 3 months' storage. Seed can best be stored in the pod in a ventilated room where pods can be fumigated regularly. In this way about 90% of the seed remains viable and germinates after 6 months' storage.

In Sumatra, seed matures during the dry season and can be sown in the field in the subsequent short rainy season. This requires adequate rainfall during the germination stage. Alternatively, seed is sown in nurseries, requiring daily watering for 1 month. Seedlings may then be transferred to polythene bags and can be planted out in the field after 1-2 months. Transplanting is preferably done at the beginning of the main rainy season. As a sole crop, a planting distance of 75 cm between rows is commonly practised, needing about 25 kg seed per ha.

Husbandry

Intensive and frequent weeding is necessary until the crop cover closes. A sole crop of P. scandens may cover the ground in 8-16 months after planting. It requires plenty of water and may compete with the main crop during the dry season. When interplanted between rubber trees, rubber yields were found to increase by up to about 165%. It is better to sow a mixed cover crop of P. scandens, Calopogonium mucunoides Desv., Centrosema pubescens Benth. and Pueraria phaseoloides (Roxb.) Benth. than to sow a sole crop, as the mixture may cover the soil already in 4 months after planting and may persist for several years.

Once established, P. scandens competes well with weeds and suppresses Imperata cylindrica (L.) Raeuschel under high rainfall conditions.

A sole cover crop of P. scandens may reach fresh weight yields per ha of approximately 4.6 t leaves, 11.3 t stems, 1.85 t roots, and 15 t litter. In Nigeria, P. scandens has been tested as a permanent cover crop, interplanted with maize. Maize planted in cleared strips in between the cover crop gave higher yields than zero tillage planting or conventional tillage. Applying N fertilizer increased yields; the highest maize yield (2.6 t/ha) was obtained with a P.scandens cover and an application of 60 kg N per ha. After 5 years, the cover crop was ploughed in and maize was sown, yielding 3.9 t/ha. This was almost double the yield of the best, conventionally planted, fertilized treatment.

Diseases and pests

P. scandens is generally little affected by diseases and pests. It is resistant to several diseases and pests affecting the closely related P. tetragonolobus (L.) DC. such as false rust (Synchytrium psophocarpi), yellow mosaic virus, leaf spot and leaf curl. It is also less susceptible to necrotic mosaic and flower blight.

The nematode Heterodera marioni attacks P. scandens in Sumatra (Indonesia) and Mauritius. In Zaire, weevils (Bruchidae) attack the seed.

Genetic resources

Strains of P. scandens are available at the International Institute of Tropical Agriculture, Ibadan, Nigeria and from the Southern Regional Plant Introduction Station, Griffin, Georgia, the United States.

Breeding

Efforts to cross P. scandens with P. tetragonolobus which has the same chromosome number, using P. tetragonolobus as the female or male parent, have failed, probably because of differences in karyotype. If interspecific hybrids can be obtained, they will probably be sterile, so it will not be easy to transfer genes for disease and pest resistance from P. scandens to P. tetragonolobus.

Prospects

P. scandens is a useful cover crop in humid areas, especially in rubber plantations; it deserves wider attention. Because of the very high protein content of the leaves, it may be a useful fodder grown as a component in pastures or as a sole crop. More research is needed on propagation, husbandry, and breeding.

Literature

• Citroreksoko, P.B., 1977. Kandungan protein jenis-jenis Psophocarpus di Jawa, Madura dan Bali [Protein contents of Psophocarpus species in Java, Madura and Bali]. Berita Biologi 2(1): 23-24.
• Gunasekera, S.A., Shanthichandra, W.K.N. & Price, T.V., 1990. Disease incidence, severity and pod yield of winged bean (Psophocarpus tetragonolobus) accessions and Psophocarpus scandens. Tropical Pest Management 36(3): 207-210.
• Harder, D., Lolema, O.P.M. & Tshisand, M., 1990. Uses, nutritional composition, and ecogeography of four species of Psophocarpus (Fabaceae, Phaseoleae) in Zaire. Economic Botany 44(3): 391-409.
• Mangoensoekardjo, S. & Soewadji, R.M., 1977. Pengaruh penutup tanah terhadap tanaman karet III. Ditinjau dari segi hasil [The influence of ground covers on rubber. III. Effect on yield]. Bulletin Balai Penelitian Perkebunan (BPP) Medan 8(4): 117-124.
• Mehra, K.L., Wulijarni-Soetjipto, N. & Soepardiyono, E.K., 1985. Indonesian economic plant resources: legume and other forage plants. Lembaga Biologi Nasional-LIPI, Bogor, Indonesia. p. 30.
• Mulongoy, K. & Akobundu, I.O., 1992. Agronomic and economic benefits of N contributions by legumes in live-mulch and alley cropping systems. International Institute of Tropical Agriculture (IITA) Research 4: 12-16.
• Pickersgill, B., 1980. Cytology of two species of winged bean, Psophocarpus tetragonolobus (L.) DC. and P. scandens (Endl.) Verdc. (Leguminosae). Botanical Journal of the Linnean Society 80: 279-291.
• Sastrapradja, S., Lubis, S.H.A., Lubis, I. & Sastrapradja, D., 1978. A survey of variation in Psophocarpus tetragonolobus (L.) DC. with reference to the Javanese samples. Annales Bogorienses 6(4): 221-230.
• Tong, T.H., Tjong, J.K. & Lubis, I.P., 1961. Psophocarpus palustris - an ideal ground cover for oil palm and rubber. Proceedings of the National Rubber Research Conference, 26 September - 1 October 1960, Kuala Lumpur. Rubber Research Institute of Malaysia, Kuala Lumpur, Malysia. pp. 312-324.
• Verdcourt, B. & Halliday, P., 1978. A revision of Psophocarpus (Leguminosae-Papilionoideae-Phaseoleae). Kew Bulletin 33: 191-227.

Authors

• N. Wulijarni-Soetjipto