Combining ability and heterosis studies in pigeonpea using A₂ cytoplasm from Cajanus scarabaeoides as source of male sterility

Fourteen newly developed A lines with A₂ cytoplasm from Cajanus scarabaeoides were mated with 5 R lines in line × tester design during kharif 2005 at the Main Pulses Research Station, Sardarkrushinagar. The resultant 70 hybrids were evaluated along with their parents and the standard checks (‘GTH 1’ and ‘GT 101’) in randomized block design with three replications during kharif 2006. Combining ability analysis evinced predominance of non-additive gene effects for all the characters indicating relevance of heterosis breeding for improving yield, growth and quality attributes in pigeonpea. The lines ‘CMSGT 33A’, ‘CMSGT 100A’, ‘CMSGT 288A’, ‘CMSGT 301A’ and ‘CMSGT 311A’ among females (A lines); and ‘GTR 27’ and ‘GTR 29’ among males (R lines) were good general combiners for seed yield and other one or more characters. ‘CMSGT 311A’ × ‘GTR 29’, ‘CMSGT 310A’ × ‘GTR 27’, ‘CMSGT 288A’ × ‘GTR 26’, ‘CMSGT 301A’ × ‘GTR 27’, ‘CMSGT 301A’ × ‘GTR 30’ and ‘CMSGT 100A’ × ‘GTR 28’ showed desired higher sca effects for seed yield per plant, number of pods per plant, 100seed weight, water absorption, leaf area index at 100 DAS and rate of photo synthesis at 80 DAS, respectively. Analysis of variance exhibited significant differences among genotypes and existence of enormous heterosis for all growth, yield and quality traits. ‘CMSGT 311A’ × ‘GTR 29’, ‘CMSGT 301A’ × ‘GTR 29’ and ‘CMSGT 100A’ × ‘GTR 30’ were the best three heterotic hybrids for seed yield per plant. These crosses also manifested high and significant standard heterosis for number of pods per plant and 100-seed weight. Cross combination ‘CMSGT 311A’ × GTR 29’ recorded the highest and significant standard heterosis for harvest index too.