Determination of combining ability effects and heterotic grouping of maize inbred lines for winter season

Abstract

The combining ability and heterotic grouping information of germplasm lines facilitates the breeders to formulate the breeding strategies for a successful hybrid development programme in maize. A field experiment was conducted to generate the information on combining ability and heterotic grouping of 61 newly developed maize inbred lines for winter season. The 122 F1 hybrids generated in line × tester mating design by crossing 61 maize inbred lines with two testers (BML-6 and BML-7) were evaluated during 2016 and 2017 at IIMR regional centre, Begusarai. Pooled analysis showed that mean squares due to genotypes, general combining ability (GCA) and specific combining ability (SCA) effects for grain yield. Out of 61 inbred lines, 29 had positive GCA with maximum GCA effect value of 25.64. On the basis of GCA effects inbred lines IMLSB-1299-5, IMLSB-406-2, IMLSB-334B-2, IMLSB-814-2 and IMLSB-285-1 were identified as best combiners which can be further used in breeding programme. The 29 lines showing positive GCA for grain yield were classified into two heterotic groups ‘A’ (12 inbred lines) and ‘B’ (17 inbred lines) based on SCA effects with testers, A and B, respectively. Four lines with positive and significant SCA for grain yield were equally distributed in heterotic group A and B. The cluster analysis formed four clusters in which 29 inbred lines were randomly distributed depicting diversity among inbred lines. Among the 122 hybrid combinations, 9 hybrids showed significant and positive heterosis over the three checks for yield. After multi-location testing, these hybrids combinations can be recommended for commercial cultivation. Based on the information generated for heterotic grouping, these inbred lines will be further used for developing heterotic pools and different heterotic combinations for further utilization.