Pigeonpea (En),
Pois d' Angole (Fr), Cajanus cajan (L.) Millsp.

Description

Pigeonepea is a perennial erect bush, 0.5 to 4 m tall, and has strong stem. It has pubescent leaves which are trifoliate. Leaflets possess vesicular glands below, which are membranaceous or rather tick. Stipellae are present or absent. Flowers are present in axillary or terminal pedunculate or almost sessile racemes. They are yellow, or lined with red, or flag is dorsally reddish, and upto 3 cm long. Bracts are small or large, caducous; bracteoles absent. Calyx are teeth acute, acuminate or elongate-acuminate; two upper ones more or less connate. Coralla are persistent or not, vexillum obovate-orbicular, reflexed, clawed, auriculate. Wings are obliquely obovate auriculate, keel rounded-oblique, obtuse. Ovary is subsessile with 3 to 10 ovoules. Style is thickened above the middle, upcurved, upper part glabrous or slightly hairy, not bearded. It has 9 stamens which are connate; vexillar is stamen free and anthers are uniform. Its fruit is a pod, linear-oblong, apex obtuse or acute, compressed, bivalved, depressed between the seeds with transverse lines, more or less septate between the seeds. Its seeds are reniform to suborbicular, shiny, white, brown, grey, purple or black, variegated or not, strophiole conspicuous or vestigial. It has deep, strong, woody tap root with well developed lateral roots in the superficial layers of the soil. It is nodulated by the cowpea group of Rhizoibum. Most nodules may vary from 2mm to 2 cm, and the shape be spherical, oval, elongate, or branched.

Distribution

Pigeonpea seems to have originated in peninsular India. It is part of many farming systems throughout the tropics and sub-tropics. Although India produces around 80% of the total crop, 2.6 million t from nearly 3.5 million hectares, it is also grown less intensively for instance in home-gardens, elsewhere in Asia, throughout Africa, and in Latin America. There is substantial area of pigeonpea in Kenya, Uganda, and Malawi in eastern Africa, and in the Dominican Republic and Puerto Rico in Central America.

Adaptation

Pigeonpea can be found growing on an otherwise arid landscape due to its ability to tolerate drought and high temperatures. Its deep root system allows for optimum moisture and nutrient utilization and break the plough pans, thus improving soil structure. It seems to have special mechanism to extract phosphorous from some soil to meet its needs. It depends on symbolically fixed N part of which (up to 40 kg N ha-1) is left as residual for the use of following crops. Its fallen leaves enrich soil organic matter. This crop is ideal for intercropping or mixed cropping because of its slow initial growth allowing companion crop, usually a coarse grain cereal, to grow unhindered. It makes major growth utilizing the residual soil moisture left after the harvest of companion crop. Local land races and cultivars of 180 to 280 days duration are often grown in this manner to exploit residual moisture in soil when it is not feasible to raise another crop in South Asia. Elsewhere, they are generally grown as perennial hedge crop. Their photoperiod sensitivity allows them to be grown as a winter crop in mild winter environments.

Short-duration pigeonpea takes 100 to 140 days to mature has been recently introduced in India now make it possible to grow a sole crop of pigeonpea before the major postrainy-season crop of wheat is sown. This was not possible earlier with the traditional, long-duration pigeonpeas. The perennial habit of short-duration pigeonpea enables the production of multiple harvests in tropical areas.

Pigeonpea is a quantitative short-day plant. The traditional long-duration land races and cultivars are photoperiod sensitive and their cultivation was confined to mainly tropical and subtropical latitudes within 30° N to 30° S. Recently developed extra-short duration cultivars are relatively less sensitive to photoperiod which enables their cultivation up to 45° N latitudes.

Crop Improvement

ICRISAT has been engaged in pigeonpea improvement research for the last 25 years. During this period concerted team efforts have metamorphosed the crop from a traditional medium to long duration, bushy, pest and disease ridden, and low yielding subsistence crop to novel early maturing, photoperiod insensitive and relatively high yielding crop with ability to escape and resist pest and disease attack. The crop has found new niches at higher latitudes to as far as 45° N to 45° S. The development of world's first hybrid is another significant advancement made at ICRISAT after it was successful in identifying sources genetic male sterility. Efforts are now on to identify cytoplasmic male sterility system to overcome problems of seed production common to hybrid based on genetic male sterility system.

Other major research topics

A number of putative souces to individual and multiple disease resistance have been identified. Efforts are being made to improve resistance to key pests such as maruca, pod borer and pod fly both in Asia and Africa. Work on enhancing drought and waterlogging resistance has been in progress.