Protein mal-nutrition is widespread among poor of developing and under developed countries. Since animal protein is beyond the reach of this group, their primary protein supply comes from plant based products. Amongst these, pigeonpea or red gram (Cajanus cajan (L.) Millspaugh) is an important food legume that can be grown under rainfed conditions with least inputs. Pigeonpea is rich in starch, protein, calcium, manganese, crude fiber, fat, trace elements, and minerals. Besides its high nutritional value, pigeonpea is also used as traditional folk medicine in India, China, Philippines and some other nations. Literature on this aspect show that pigeonpea is capable to prevent and cure a number of human ailments such as bronchitis, coughs, pneumonia, respiratory infections, dysentery, menstrual disorders, sores, wounds, abdominal tumors, tooth ache, and diabetes.

Male-sterility has been successfully used for enhancing yield in a number of cereal and vegetable crops. In food legumes, this technology could never be used either due to non-availability of natural outcrossing system, or an efficient male-sterility system or both. Pigeonpea [Cajanus cajan (L.) Millsp.] is a partially cross-pollinated food legume and recent success in breeding a stable male-sterility system has allowed breeders to exploit hybrid vigour for increasing yields. The cytoplasmic-nuclear male-sterility (CMS)-based hybrids have recorded 28.4% yield superiority over local checks in farmersÕ fields. This paper besides summarizing the reports of all the genetic and CMS systems, also discusses the prospects of utilizing these male-sterility systems in commercial hybrid breeding programmes.

ICRISAT scientists, working with Indian programme counterparts, developed the world's first cytoplasmic-nuclear male sterility (CMS)-based commercial hybrid in a food legume, the pigeonpea [Cajanus cajan (L.) Millsp.]. The CMS, in combination with natural outcrossing of the crop, was used to develop viable hybrid breeding technology. Hybrid ICPH 2671 recorded 47% superiority for grain yield over the control variety 'Maruti' in multilocation on-station testing for 4 years. In the on-farm trials conducted in five Indian states, mean yield of this hybrid (1396 kg/ ha) was 46.5% greater than that of the popular cv. 'Maruti' (953 kg/ha). Hybrid ICPH 2671 also exhibited high levels of resistance to Fusarium wilt and sterility mosaic diseases. The outstanding performance of this hybrid has led to its release for cultivation in India by both a private seed company (as 'Pushkal') and a public sector university (as 'RV ICPH 2671'). Recent developments in hybrid breeding technology and high yield advantages realized in farmers' fields have given hope for a breakthrough in pigeonpea productivity.

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Recently, a breeding technology for hybrid pigeonpea [Cajanus cajan (L.) Millsp.] based on cytoplasmic‐nuclear male sterility (CMS) and partial natural outcrossing was developed at ICRISAT. The limited number of experimental hybrids tested has shown the presence of a considerable amount of hybrid vigor for seed yield. In the present study, one extra‐early‐ (120 d), two early‐ (150 d), and two late‐maturing (180 d) pigeonpea hybrids were studied to generate information on the genetics of fertility restoration of the A4 CMS system. In the extra‐early‐maturing hybrids, pollen fertility was controlled by a single dominant gene, whereas in the early‐ and late‐ maturing hybrids, male fertility was governed by two duplicate dominant genes. It was also observed that hybrids with two dominant genes produced a greater pollen load and expressed greater stability as compared with those carrying a single dominant gene. The information on the inheritance of fertility restoration will help in designing strategies for breeding elite hybrid parents, and it was concluded that for breeding hybrids with stable fertility restoration, the presence of two dominant genes is essential.

11Pigeonpea is an important legume crop of the semi-arid tropics. In India, pigeonpea is mostly 12 grown in water-logging prone areas resulting in major production losses. It is imperative to 13 identify genotypes which show tolerance at the critical crop growth stages to prevent these 14 losses. A panel of 272 diverse pigeonpea accessions was evaluated for seed level water 15 submergence tolerance for different durations (0 h, 120 h, 144 h, 168 h, and 192 h) under in-16 vitro conditions in the laboratory. All genotypes exhibited high (79 to 98.6 %) survival rates 17 for up to 120 h of submergence. After 192 h of submergence, the hybrids as a group, 18 exhibited significantly higher survival rates (79%) than the germplasm (71%), elite breeding 19 lines (68%), and released cultivars (58%). Ninety-six genotypes representing the phenotypic 20 variation observed during the laboratory screening were further evaluated for water-logging 21 tolerance at the early seedling stage using pots, and survival rates were recorded eight days 22 after completion of the stress treatment. Genotypes were further narrowed down from 96 to 23 49 in order to evaluate their performance under natural field conditions. Among the cultivated 24 varieties and hybrids the following were identified as tolerant after three-levels (In-vitro, pot 25

Considering the increasing demand for pigeonpea [Cajanus cajan (L.) Millsp.], especially in India, breeders have realized the need to develop high-yielding, super-early maturing (<90 d) lines that could be planted in a wider range of latitudes and/or altitudes to enhance the crop adaptation and to diversify the legume-based cropping systems. The International Crops Research Institute for the Semi-Arid Tropics (iCRISAT) initiated a breeding program in 2006 to develop "super-early" (flowering in <50 d) determinate (DT) and nondeterminate (NDT) pigeonpea lines. Eleven parental lines with days to 50% flowering ranging from 49 d (MN 5) to 103 d (ICP 6974) were crossed using a full diallel mating design. A pedigree-based approach was followed to select for early flowering. The selection gain was larger initially (reduction of 7 d) but there was less reduction (2 d) from Fg to F^. Determinate and NDT lines that flowered in 45 to 56 d at ICRISAT-Patancheru reached advanced (Fg and Fg) generations. The newly developed lines flowered and matured at a higher latitudes (tested at 30° N vs. 17° N) and altitudes (tested at 1250, 545, and 247 m asi). These lines could be used in new cropping systems (i.e., pigeonpea-wheat [Triticum aestivum L.]) that would allow expanding pigeonpea production to nontraditional planting areas (i.e., wider latitudes and higher altitudes) and could even offer wider planting time flexibility to farmers.