Identification of fertility restorers, stable combiners and heterotic combinations across environments in pigeonpea [<em>Cajanus cajanifolius</em> (L.) Millsp.] in India

Abstract

Efficient and stable cytoplasmic genic male sterility system is a prerequisite for commercial exploitation of heterosis in any crop improvement program. The present investigation was undertaken to identify fertility restorers, stable combiners and best heterotic crosses in pigeonpea [Cajanus cajanifolius (L.) Millsp]. Totally, 75 crosses were developed by using three A4 cytoplasm-based male sterile lines viz., ICPA 2047, ICPA 2092 and ICPA 2089, and 25 diverse inbred lines. The pollen fertility assay identified 15 good restorers with 85-95% fertility status. The 45, best restored combinations identified were assessed across four seasons (August and September, 2012 and 2013) for their stable heterosis and general and specific combining ability to identify parents possessing desirable genes. Variance for combining ability was significant (p<.05) for lines, testers and line × tester effects. Among the three male sterile lines, ICPA 2047 was stable with a significant general combining ability for most of the traits followed by ICPA 2092, while the general combining ability effects among males was high across seasons for ICPL 20205 and ICPL 20177 (p<0.05). The cross combination of ICPA 2089 × ICPL 20205 had desirable genes for days to the first flowering, 50% flowering and maturity. For yield related traits, cross combinations of ICPA 2047 × ICPL 20128, ICPA 2092 × ICPL 11376 and ICPA 2047 × ICPL 20107 had significant specific combining ability indicating their usability in development of hybrids (p<0.05). With respect to the heterotic ability of crosses, crosses involving parents ICPA 2089 as female and ICPL 88034 and ICPL 81-3 as males showed negative heterosis for flowering and maturity. For yield related traits, crosses with ICPA 2047 as the female parent and ICPL 20128, ICPL 20177 and ICPL 20096 as the male parents showed significant positive heterosis (p<0.05). The identified parents with good combining ability and cross combination`s with significant heterosis could be utilized in producing high yielding hybrids in pigeonpea.