Influence of different temperature regimes on seed setting behavior and productivity traits in rabi sorghum

The experiment was conducted involving 35 rabi sorghum genotypes sown at six different dates of sowing (from Sept Ist week to October IVth week) during 2006-07 to assess the stability for pollen fertility (%), seed setting (%) and other productivity traits viz., plant height, days to 50% flowering, number of leaves, length of panicle, panicle weight, panicle diameter, number of primaries/panicle and 500-grain weight. The influence of dates of sowing on different phenotypic characters indicated that delayed sowing reduced the expression of all the traits. Flowering was early when genotypes were sown at 3rd date. The grain yield in general was high in the Ist date of sowing compared to the remaining dates. The seed set % (irrespective of sowing dates) was more than 65 as long as minimum temperature was more than 13 ºc where as, it was drastically reduced when minimum temperature was dropped down below 10 ºc. Pooled analysis of variance revealed significant difference among the genotypes and environments for all the characters indicating genotypes and environments tested were diverse in nature. The G x E interaction was high and linear for most of the characters indicating significant and linear response of genotypes to changing environment for these traits. On the basis of stability parameters it was revealed that the two genotypes viz., DSH 4 and M 35-1 were stable for majority of the characters across the dates of sowing. As far as pollen fertility is concerned M31-2B, BJMS2B, 27B, 101B, BJMS204B, SPV570, BRJ62, RS29, AKR 150, BRJ 358, DSV5, DSV4, M35-1, DSH4, and CSH14 were stable in all the dates of sowing. The genotypes 1409B, 116B, M31-2B, 101B, R354, C43, DSV5, DSV4, M35-1, DSH4 and BRJH 129 were stable in seed setting behavior across the dates of sowing. With respect to grain yield/plant the two genotypes viz., 116B and M35-1 were most stable. In general, the B lines showed less stability for many characters and the hybrids were found to be more stable across the dates of sowing for many characters indicating the scope for development of hybrids for rabi season. Among the hybrid parents R lines exhibited stability for many characters across the dates of sowing while B lines were found to be not stable indicating the need for the development of stable B lines for rabi ecosystem. Among the 35 genotypes the lines viz., 296B, AKMS14B, C43, AKR150 and B35 were not stable for any of the characters indicating their sensitivity to rabi environment as a whole.