Identification of Superior Maize Hybrids Based on Heterosis for Yield and its Component Traits

Abstract

Background: The dominance hypothesis attributes heterotic performance to partial or complete dominance, whereby favourable dominant alleles mask deleterious recessives, resulting in heterozygote values exceeding the parental mean Aim: The present study aim to evaluate the magnitude of heterosis for yield in maize to identify superior hybrid combinations for yield enhancement and earliness. Study Design: A Line × tester mating design followed by evaluation in a Randomized Block Design (RBD) with three replications. Place and Duration of Study: The study was conducted at Agricultural College, Polasa, Jagtial district, Telangana, India. Crosses were made during kharif 2022 and hybrids were evaluated during rabi 2022–23. Methodology: Six inbred lines were crossed with four testers to produce 24 F₁ hybrids. These hybrids, along with their parents and standard check (DHM-117), were evaluated for 12 traits including flowering traits (days to 50% anthesis, days to 50% silking, anthesis–silking interval, days to maturity), yield components (ear length, ear girth, kernel rows per ear, kernels per row, 100-kernel weight), plant traits (plant height, ear height and grain yield per plant. Relative heterosis (mid-parent), heterobeltiosis (better parent), and standard heterosis (over check) were estimated. Negative heterosis was considered desirable for earliness traits, while positive heterosis was desirable for yield and its components. Results: Analysis of variance revealed significant differences among genotypes for all traits, indicating substantial genetic variability. Significant negative heterosis for flowering and maturity traits indicated potential for early maturing hybrids. Grain yield per plant exhibited high heterotic expression, with mid-parent heterosis up to 90.69%, heterobeltiosis up to 57.81%, and standard heterosis up to 27.45%. Eight hybrids showed significant positive standard heterosis for grain yield. Hybrids PFSR 132 × BML 6, PFSR 135 × BML 6, PFSR 70 × CML 286, PFSR 135 × CML 451 and PFSR 29 × BML 7 emerged as promising combinations for yield improvement. The results indicate substantial genetic diversity and scope for exploiting heterosis in maize breeding programs. Conclusion: Studies on standard heterosis for grain yield per plant revealed that the crosses PFSR 132 × BML 6, PFSR 135 × BML 6, and PFSR 70 × CML 286 exhibited the highest significant positive standard heterosis among the evaluated hybrids. The superior performance of these crosses indicates their strong heterotic potential for grain yield improvement. Furthermore, these hybrids demonstrated favourable heterotic expression in the F₁ generation, suggesting the presence of desirable gene combinations that could be effectively exploited in breeding programmes. Therefore, these promising crosses may be advanced to subsequent generations in order to isolate and identify superior transgressive segregants with enhanced yield potential and desirable agronomic characteristics.