Assessment of combining ability and heterosis for yield and yield related traits in maize (Zea mays L.) under irrigated and partially irrigated conditions

Abstract

The experimental material consisted of 12 genetically diverse maize inbred lines (ILs). A total of 66 cross combinations were developed using a half diallel mating design. These 12 parental lines, along with their 66 F1 hybrids and 2 national checks (total 80 entries) were evaluated in randomised block design (RBD) with two replications under irrigated and partially irrigated conditions across two seasons during rabi 2019–20 and kharif 2020 at the research field, Department of Genetics and Plant Breeding, College of Agriculture, Rajmata Vijayaraje Scindia Krishi Vishwa Vidyalaya (RVSKVV), Gwalior, Madhya Pradesh, India. Analysis of variance (ANOVA) revealed significant differences among the genotypes for all the characters studied, indicating the presence of substantial genetic variability. Estimates of general combining ability(GCA), specific combining ability (SCA) and heterosis were computed. The significance of heterosis was tested using the standard error of the respective check varieties. The GCA effects indicated that IL6, IL7, IL9, IL10, IL11 and IL12 were good general combiners for seed yield per plant (SYP). Among the hybrids, cross combination IL1 × IL11 exhibited the highest positive and significant SCA effect, followed by IL1 × IL7, IL3 × IL10, IL4 × IL6 and IL7 × IL8. In contrast, IL4 × IL7 showed a significant negative SCA effect, followed by IL1 × IL6, IL5 × IL7 and IL3 × IL2. For heterosis, the crosses viz., IL1 × IL10 and IL4 × IL7 exhibited desirable positive heterosis for grain yield, whereas IL7 × IL9 (heterobeltiosis) and IL2 × IL4 (standard heterosis) showed significant negative heterosis. Yield and its improvement were strongly associated with component traits such as plant height (PH), cob length (CL), number of kernel rows per cob (NKRC), number of kernels per row (NKR),number of cobs per plant (NCP), cob girth (CG), 100-grain weight (HGW) and shelling % (SP). Therefore, hybrids exhibiting positive heterosis for these traits can be effectively utilised in breeding programmes to enhance grain yield, as positive heterosis is economically advantageous and contributes to higher productivity.