University Of Agricultural Sciences, Bangalore

Contact Details
Dr. M. Byre Gowda
Pigeonpea & Dolichos Breeder
University of Agricultural Sciences
GKVK, Bangalore - 560 065
India
Phone
+91 80 22736043
Mobile
+91 9741414657
Fax
+91-80-23330277
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Dolichos Bean - Lablab purpureus (L.) Sweet

About the Crop > Botany & Taxonomy

Botany & Taxonomy

Botanical name: Lablab purpureus (L.) Sweet
Order: Fabales Family: Fabaceae Subfamily: Faboideae Species: Lablab purpureus
Tribe: Phaseoleae Sub-tribe: Faboideae Genus: Lablab

It is a perennial herb, frequently grown as an annual. Usually twining to reach 5-29 feet, but bushy, semi-erect, and prostrate forms exists. Probably no other legume shows such variation in form and habit. The tap-root is well developed with many laterals and well developed adventitious roots.

Purseglove (1968) has recognized two types of Lablab in India and are sometimes considered as distinct species. They are:

Dolichos lablab var. typicus Prain: It is commonly called Lablab bean, Bonavist bean, Hyacinth bean, Indian butter bean (Hindi-Sem; Bengali-Shim; Gujarathi-Val; Marathi-Pavta; Telugu-Chikkudu; Tamil-Avarai; Kannada-Chapparadavare; Malayalam- Avara.)

A perennial twining herb, cultivated mostly as an annual, distributed throughout the tropical and temperate regions of Asia, Africa and America. In India, it is grown as a garden crop. Several types differ in colour of flowers, size, shape and texture of pods and size and colour of seeds. A type with showy purple flowers is cultivated as an ornamental plant in temperate regions. The pods are white, green or purple-margined. Seeds white, yellow, brownish, purple or black.

Dolichos lablab var. lignosus Prain: It is commonly known as Australian pea, Field Bean. (Hindi - Ballar; Gujarati - Val; Telugu - Anumulu; Tamil - Mochai; Kannada - Avare; Malayalam - Mochakotta).

It is a semi-erect, bushy, perennial herb, cultivated as an annual. It shows little or no tendency to climb. Leaflets innately trifoliate, smaller than those of var. typicus. Flowers borne on a straight upright stalk, often a foot high on which they open in succession. Pods oblong, flat and broad, firm-walled and fibrous, contain 4-6 seeds with their long axis at right angles to the suture. Seeds almost rounded white, brown or black. The plant emits a characteristic odour.

Cylindrical , twining upto 6 meters in length, hairy or glabrous, usually 2-3 meters, but often to 10 meters long. Other forms, dwarf and bushy.

Leaves

Leaves alternate, trifoliate, leaflets ovate, 5-15 cm x 4-15 cm, often hairy. Leaflets very broad, ovate, the lateral ones lopsided, 7.5-15 cm long and nearly as broad, rather abruptly acuminate.

Inflorescence is a stiff axillary raceme with many flowers. Peduncle: 4.0-8.5 x 13.5-23.0 cm, often somewhat compressed, glabrescent; rachis: 2.5-6 x 13.0-24.5 cm; flowers: 1-5 together form tubercles on rachis, bracts 1 per flower, deciduous, ovate to elliptic, 5 mm long with prominent veins, sparsely pubescent; pedicels short and square, with two bracteoles attached at the base of the calyx.

Flowers

Flowers are white, pink, red or purple colored, in clusters of 4-5, each with 2 large basal bracts, anthers uniform, upper 2 sepals connate purple to pink or white, 2-4 at each node in an elongating raceme upto 2.5 cm long. Stamens diadelphous (9+1), stamen free, long, flattening and genicorlate near the base. Anther ellipsoid, basified irregularly, minutely denticulate and yellow. Ovary sessile, 10 mm long, finely pubescent. Long beaked four ovulate with inner ovarial wall speckled with tiny brown dots, style abruptly upturned, 8 mm long, laterally compressed, apical part thinly pubescent, persistent on pod. Stigma capitate and glandular.

Flowers

Flowers open generally two days after anther dehiscence. Opening is mostly between 11.00 am to 5.00 pm. It is generally self-pollinated. However, about 6-10% cross- pollination is observed. Pod setting is about 20 per spike. For the purpose of crossing, the buds that are likely to open next day afternoon are selected. A cut with forceps is made on the ventral side to 2/3 of the bud and tips are clipped off. This clipping technique, which was earlier found successful with cowpea, has worked well with this crop as well. This way crossing is made easy. More than 100 flowers can be crossed in one hour by two persons with 20-25 % success rate.

The stigma of L. purpureus was wet and papillate. The secretion of the exudate started at the tip of the stigma 4 days before anthesis. It was maximum at the time of pollination after which it decreased gradually. The exudates consisted of unsaturated lipids, reducing acids, proteins, phenols, insoluble polysaccharides and alkaloids. It plays a variety of roles including the protection of the stigma from desiccation and chewing insects (Kumar and Bhatnagar, 1989).

Studies of flower development in the 3 strains ICB002, ICB003 and ICB005 showed that the anthers and stigmas remained in close proximity to each other at optimum maturity. The pollen reached maturity and the stigma was fully receptive at the stage when the standard-base of the flower in bud had split. Viable pollen for hand pollination was best obtained from flower buds with split standard-bases before anthesis had occurred.

Emasculation and pollination resulted in fruit set percentages of up to 33%, and was most successful when emasculation was carried out before noon and pollination was performed on the same or following day. Bagging after emasculation and pollination increased the percentage fruit set to 63%; it is suggested that this may have been due to the protection of pollen and stigmatic exudates from the drying effects of the sun( Chowdhury, et al., 1989).

Flowers

Pods flat or inflated, pubescent or smooth, papery, straight or somewhat curved, white, green or purplish in colour and can vary in length from approximately 5 - 20 cm and in width from 1 - 5 cm. They may be crescent-shaped to more or less straight and ventrally deeply curving. Cultivars grown for vegetables have pods with thick, fleshy skins with practically no fiber. Pods may be septate or non-septate; in the former each seed occupies a separate compartment in the pod, while in the latter the pods have bloated appearance. Each pod normally contains three to six seeds. They are generally less than 1.25 cm in length and may be rounded or oval or rather flattened, white, cream, red, brown or black. The hilum is white, prominenand oblong, usually covering one third of the seed

Pods

Seeds variable in size and colour, normally upto 12.5 cm in length, colour ranging from white, red, brown, black or speckled, rounded or oval, hilum white, prominent, approximately 10 mm in length, average weight of 100 seeds is 25 - 40 g. Germination is epigeal.

Studies in Dolichos LabLab (ROXB.) and The Indian Field and Garden Bean. I.