Heterosis and combining ability study in hybrids developed on A₂ cytoplasm of Cajanus scarabaeoides (A lines) and its fertile counterparts (B lines) in pigeonpea [Cajanus cajan (L.) Millspugh]

With an objective to ascertain the impact of A₂ cytoplasm on heterosis and combining ability; 3 diverse A₂ cytoplasm based CGMS ‘A’ lines (‘CMSGT 301A’, ‘CMSGT 308A’ and ‘CMSGT 311A’) along with their fertile counterparts ‘B’ lines (‘GT301B’, ‘GT 308B’ and ‘GT 311B’) as females were crossed to 5 diverse fertility restorers ‘R’ lines (‘GTR 7’, ‘GTR 23’, ‘GTR 29’, ‘GTR 34’ and ‘GTR 44’) as testers in a line x tester mating design during kharif 2010 at Centre of Excellence for Research on Pulses, S. D. Agricultural University, Sardarkrushinagar, Gujarat. The resultant 30 hybrids were evaluated along with 8 parents (5 testers and 3 B lines) and the standard check (‘GTH 1’ and ‘GT 101’) in randomized block design with three replications during kharif 2011. Combining ability analysis evinced predominance of non-additive gene effects for all the characters indicating relevance of heterosis breeding for improving yield and other characters in pigeonpea. There was a drastic impact of A₂ cytoplasm on the combining ability of ‘A’ lines. However, this impact was not linear and varied with background of genotype and specific character. ‘CMSGT 301A'among femalesand ‘GTR 7’and‘GTR23’among males (R lines) were good general combiners for seed yield and one or more other characters. ‘GT 311B’ x ‘GTR 44’, ‘GT 301B’ x ‘GTR 29’ and ‘CMSGT 308A’ x ‘GTR 7’ exhibited highly significant positive sca effects for seed yield. ‘CMSGT 301A’ x ‘GTR 7’, ‘CMSGT 301A’ x ‘GTR 23’ and ‘CMSGT 308 A’ x ‘GTR 7’ were three best heterotic hybrids for seed yield engaging A lines as female indicating A₂ cytoplasm based sterility can be appropriately used for heterosis breeding in pigeonpea. Among these, ‘CMSGT 308 A’ x GTR 7’ recorded the highest and significant standard heterosis and high sca effects for seed yield that can be exploited commercially in pigeonpea.