Heterotic grouping in maize using the specific and general combining ability method

Abstract

Maize being a highly cross-pollinated crop, hybrid breeding is commercially proven due to the high amount of heterosis, and the quantum of heterosis is maximized when lines from opposite heterotic groups are mated. The analysis of variance recorded significant differences among the different quantitative characters. Similarly, ANOVA for combining ability revealed that the mean sum of squares due to lines, testers, and line-tester interaction was significant. Hence, these lines were subjected to heterotic grouping using the HSGCA method. The 32 maize inbred lines were grouped into heterotic groups A (8), B (6), and AB (9). While nine lines were unclassified into any of the groups, The lines grouped under the AB heterotic group recorded the highest gca effects for grain yield, viz., GPM-27 (25.5), GPM-18 (20.3), and GPM-606 (17.0). Whereas GPM-114 (4.3) and GPM-702 (4.2) recorded the highest gca for grain yield from heterotic groups A and B, respectively. The lines belonging to the AB heterotic group GPM-27 (96.7 q/ha), GPM-18 (91.6 q/ha), GPM-606 (88.3 q/ha), and GPM-30 (83.3 q/ha) also recorded the highest mean grain yield. Similarly, the line (GPM-114) with the highest mean grain yield and gca from heterotic group A, when crossed with GPM-706 from heterotic group B, may result in a high-yielding heterotic hybrid. Overall, the two test hybrids GH-1809 (101.93 q/ha) and GH-1829 (101.71 q/ha) recorded significantly higher grain yield as compared to the best-check 900M Gold (95.74 q/ha). Both these hybrids, GH-1809 (GPM-27 × CM-111) and GH-1829 (GPM-606 × CM-111), had female lines from the AB heterotic group with the highest gca effects for grain yield and CM-111 as their common tester.