The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) has developed the technology to produce cytoplasmic male-sterility (CMS) based hybrid pigeonpea from a cross involving Cajanus cajanifolius, a wild relative of the cultivated pigeonpea. Plant breeders can now use this technology to produce stable hybrids for commercialization, which can almost double the productivity to about 3 tons per hectare, in comparison to released commercial varieties.

According to Dr William Dar, Director General of ICRISAT, the new CMS-based pigeonpea hybrid technology is a breakthrough that takes pigeonpea research into the next quantum. This technology has overcome some of the limitations that had been limiting pigeonpea hybrid research for many years. This research was made possible through ICRISAT's partnership with the Indian Council of Agricultural Research (ICAR) and private-sector companies. Using this technology, ICRISAT developed and tested more than 200 hybrids. In this year's evaluation, three experimental hybrids showed near-doubled productivity, high stability and no plant deformity. The new experimental hybrids have also generated high interest among partners because of their high productivity, low labor requirement for seed production and greater drought tolerance.

Pigeonpea (also known as Tuvar Dal or Arhar dal in India) is annually grown over 4 million hectares by Indian resource-poor farmers. Prepared and consumed in a variety of forms, pigeonpea is a cheaper protein source for a billion people. Since it commands a relatively higher price in the marketplace, small-holder farmers use it both as a cash generator and as a house-hold food. In spite of releasing several varieties in the past, the crop's productivity had plateaued at low levels, raising concern among scientists and farmers alike.

The new hybrid technology has broken the barrier and doubled productivity. Using the CMS-based hybrid technology, pigeonpea experimental hybrids have been developed for all the three maturity groups for the crop, according to Dr KB Saxena, Principal Pigeonpea breeder at ICRISAT.

While the short-duration pigeonpea varieties mature between 120 and 140 days, the medium-duration ones mature between 160 and 180 days, and the long-duration ones take more than 250 days. The ability to survive water-scarce situations is higher for the CMS-based hybrids, since they produce 30 per cent more root mass than other varieties. This is of significance since pigeonpea is the crop of the water-scarce regions, and more crop per drop is the need of the farmers. The roots of this legume have the ability of bringing the nutrients to the top, and also fix nitrogen in the soil, thereby making it an excellent intercrop.

The success of CMS hybrid research lies in ICRISAT's partnership with the Indian Council of Agricultural Research (ICAR) institutions and private-sector companies. The Institute is partnering with seven private seed companies through a Hybrid Parents Research Consortium. The strongest private-sector support was from the Maharashtra Hybrid Seed Company (MAHYCO). In recognition of this support, ICRISAT named the CMS system as the Barwale CMS System in Pigeonpea, honoring Dr BR Barwale, Chairman of Mahyco. ICRISAT is providing for the transfer of CMS technology to ICAR, private sector seed companies and also the Chinese Academy of Agricultural Sciences. What is cytoplasmic male-sterility based hybrid technology for pigeonpea?

The CMS technology involves crossing the wild relative of pigeonpea Cajanus cajanifolius with the cultivated variety. Through a series of six backcrosses (crossing the offspring back with the cultivated variety) a male-sterile progeny is created, which has the cytoplasm (the living liquid inside the plant cell) of the wild species and the nucleus of the cultivated variety. The male sterile progeny resulting from this cross is then crossed with other fertile restorer lines, resulting in all fertile offspring.

The need for creating male-sterile parent was felt because pigeonpea is an often cross-pollinated plant. By creating male-sterile plants, out-crossing was ensured by planting them adjacent to the fertile cultivated variety. Insects did the rest, thereby reducing the labor cost for manual crossing.

The CMS hybrid overcomes the limitations of an earlier generation of pigeonpea hybrids developed by ICRISAT and partners. During the late 1980s, ICRISAT had convened an inter-institutional effort in India that developed the world's first hybrid pigeonpea. But that hybrid was difficult to produce on a commercial scale, because it used genetic male sterility - a system that required intensive field labor to remove any fertile plants to avoid contamination. This invoked high labor costs and skill requirements among seed producers. As a result, the hybrid seed industry never fully realized the potential of the hybrid technology.