Unveiling combining ability and heterotic grouping of newly developed winter maize (Zea mays) inbreds

Pooled analysis of the test-crosses evaluation of 61 newly developed maize (Zea mays L.) inbred lines using two inbred tasters namely BML-6 and BML-7 during rabi 2016-17 and 2017-18 at ICAR-IIMR Regional Centre, Begusarai revealed significant variation among genotypes, general combining ability (GCA) and specific combining ability (SCA) effects for all the traits. Out of 61 inbred lines, 29 exhibited significant positive GCA effect for grain yield with maximum GCA effect value of 25.64. Inbred lines, viz. IMLSB-1299-5, IMLSB-406-2, IMLSB-334B-2, IMLSB-814-2 and IMLSB-285-1 were identified as the best general combiners on the basis of GCA effects which can be utilized to a greater extent in hybrid breeding programme. Out of 29 inbred lines with significant positive GCA effects, 12 and 17 lines also showed significant positive SCA effects with tester, BML-7 and BML-6 respectively, thus were classified into two heterotic groups 'A' and 'B', respectively. Out of 122 test-crosses, 14 exhibited significant and positive heterosis for yield over three national checks. The information generated on the heterotic grouping will help in further streamlining the available germplasm into heterotic pools and thereby augmenting the national hybrid breeding programme.