Studies on Gene Action and Combining Ability of Cytoplasmic-Genic Male Sterility System based Hybrids in Pigeonpea [<i>Cajanus Cajan</i> (L.) Millsp.

Abstract

The present investigation was undertaken with different newly developed six cytoplasmic male sterile (A) lines and five pollen fertility restorers (R) lines as testers were crossed in a line x tester mating design for ascertaining their general and specific combining ability for yield and its component traits in pigeonpea [ Cajanus Cajan (L.) Millspaugh.]. The mean sum of squares due to line x testers interaction were significant for all the characters except plant height, revealed the significant contribution of hybrids for specific combining ability variance components. The ratio of σ2gca/ σ2sca being more than unity was found for the traits, days to flowering, days to maturity, plant height and biological yield, which indicated greater role of additive genetic variance for the inheritance for these traits suggesting and indicated to further improvement as a source of favourable genes for earliness and yield improvement through selection of desired transgressive segregants from segregating generation. The ratio σ2gca/ σ2sca being less than unity was found for the traits, number of branches per plant, number of pods per plant, number of seeds per pod, pod length, 100-seed weight, seed yield per plant, harvest index, protein content and leaf area, which exhibited greater role of non- additive genetic variance for the inheritance for these traits and indicated to exploitation of these traits for improvement of yield through heterosis breeding. Among parents, CMS GT 603 A (28.43) and GTR 95 (17.24) were good general combiner for seed yield and its contributing traits viz . pod length, number of branches per plant, number of pods per plant, number of seeds per pod, pod length, biological yield and leaf area, CMS GT 33 A (0.48) and CMS GT 301 A (0.19) for protein content, CMS GT 33 A (-17.93), CMS GT 288 A (-9.03), GTR 52 (-1.40) and GTR 8 (-0.62) recorded for earliness. These parents can be improved further through intensive crossing programme and subsequent selection of transgressive segregants in desired direction. Hybrids CMS GT 33 A X GTR 18 (29.31), CMS GT 302 A X GTR 8 (25.27), CMS GT 601 A X GTR 52 (21.35) and CMS GT 288 A X GTR 95 (20.89) were the best for seed yield per plant . These crosses had also high sca values for its contributing traits viz . number of branches per plant, number of pods per plant, pod length, harvest index, biological yield and leaf area. These crosses involved poor x average, poor x poor and average x poor combining parents and better performance reflected involvement of interaction of dominant and epistasis type gene action for this trait. So, these crosses can be exploited through hybrid breeding programme.