EXPRESSION OF HETEROSIS FOR GRAIN YIELD AND COMPONENT TRAITS IN ELITE MAIZE (ZEA MAYS L.) HYBRIDS ACROSS CONTRASTING ENVIRONMENTS

Abstract

Heterosis is a major breeding strategy for enhancing productivity and associated agronomic traits in maize. The present studies had undertaken to estimate the heterosis for grain yield and its component traits in elite maize inbred lines. The 25 F₁ hybrids were developed using a line × tester mating design involving five lines and five testers, along with two standard checks. The hybrids and their parents were evaluated in a randomized block design with two replications across three environments, namely Kolhapur, Gurugram (NCR) and Jalna. Heterosis was estimated as mid-parent heterosis (MPH), better-parent heterosis (BPH) and standard heterosis over two checks (SH₁ and SH₂) for ten quantitative traits. Pooled analysis revealed substantial cross-specific variation in heterotic expression. For grain yield, MPH ranged from -18.72 to 15.61%, BPH from - 23.04 to 4.49%, SH₁ from -16.66 to 7.75% and SH₂ from -16.07 to 8.52%. The cross IC297843 × EC639266 recorded the highest MPH (15.61%) and BPH (4.49%) for grain yield, whereas IC297841 × EC639023 exhibited the highest standard heterosis over Check 1 (7.75%) and Check 2 (8.52%). Considerable heterosis was also observed for yield contributing traits. IC297841 × EC632062 recorded high heterosis for cob length, while IC298591 × EC632049 showed the highest MPH (16.14%) and BPH (14.29%) for 100-seed weight. For earliness, IC297843 × EC639023 consistently expressed desirable negative heterosis for tasseling and silking. The results demonstrated that heterotic expression was highly dependent on cross combination and trait, highlighting the importance of evaluating multiple heterosis criteria across environments. The identified cross combinations can provide useful material for further maize hybrid breeding and yield improvement.