Vigna hosei (Craib) Back.

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Leguminosae

Synonyms

Dolichos hosei Craib.

Common names

Vigna (Far East).

Description

A twining or creeping legume, often forming a thick ground cover. Leaflets ovate-elliptic, on both surfaces thin, long hairs; terminal leaflet 3 to 7.5 cm x 2 to 5 cm; pod 1 to 2 cm long, black, one- to three-seeded. Besides producing normal flowers and pods, it also produces some which remain concealed under a dense carpet of half-decayed leaves, originating from the plant itself and which are borne on a 2. 5- to 6-cm pale stalk; in a ripe state they are very yellow, finely and rather densely pubescent, one- to two-seeded, 1 to 1.5 cm long.

Distribution

Widespread in the humid tropics, native of north Borneo. Occurs from sea level to 1 100 m.

Characteristics

Perennial summer-growing legume, but has some active growth in the cool season. Requires 2 500 mm or more annual rainfall and has low tolerance of dry weather, but will stand flooding.
Bunting (1930) found that it gave good growth under coconuts as a green manure. It is adapted to a wide range of soil textures and prefers an acid soil of pH 4.9 or less (Grof, personal communication). It is nonspecific in its Rhizobium requirement, but preferably should be inoculated with a selected cowpea strain such as CB 756 (Norris, 1967).
Spreads very rapidly under natural conditions, but for establishment it is better to prepare a good seed bed and drill in the seed at 1 kg./ha at a depth of 1.25 cm and harrow or roll after seeding. Midsummer sowing is recommended. Seed has a hard coat and should be treated with concentrated sulphuric acid for ten minutes to break dormancy. It has fair seedling vigour and thereafter grows vigorously and suppresses weed growth. It fixes significant amounts of nitrogen and combines well with guinea, pangola and Brachiaria grasses.
Early grazing should be light, but once established it can tolerate heavy stocking. Fire and drought have serious effects on the swards. Flowers in about 180 days from seeding and is self-fertilized. Seed production is poor and only about 50 kg./ha can be harvested; a suction harvester is required. (Plants can be chemically defoliated before using the suction harvester). Leaf-eating caterpillars may attack the crop during its vigorous growth in midsummer.
Main attribute is its persistence in sward-forming grasses, having a stoloniferous habit of growth. Main deficiencies are poor seed-setting and difficulty of harvesting seed on a field scale.

Links for the genus:

  • Vigna germplasm: Current status and future needs (report prepared by the Vigna Crop Germplasm Committee)