Exploring the Genetics of Heat Tolerance through Yield Performance Evaluation in Tropical Maize (Zea mays L.)

Heat stress severely affects maize yield and productivity, making it essential to identify and select heat-tolerant genotypes. Three hundred seven testcrosses derived from a biparental population were evaluated during summer at two distinct high VPD environments along with four checks (P1844, P1855, DKC9108 and DKC9162) to know their performance and association of traits under heat stress conditions. Analysis of variance revealed significant variability among the testcrosses, indicating substantial genetic diversity. Correlation analysis identified strong positive correlations between grain yield and related traits like plant height and ears per plant, highlighting these as vital selection criteria in breeding programmes. Additionally, Best Linear Unbiased Predictors (BLUPs) were utilized to evaluate the per se performance of the testcrosses, identifying the top-performing ones with superior heat tolerance. These top testcrosses achieved an average grain yield of 3.47 t ha-1, surpassing the population mean of 3.13 t ha-1. The top 10% of selected testcross families exhibited a yield gain of 0.34 t ha-1, representing a 9.79% improvement over the population under heat stress conditions. In order to create resilient maize hybrids, the study effectively isolated 18 elite testcrosses with improved heat tolerance that outperformed the superior check P1844. This provides a mitigation method for reducing the negative effects of climate change on maize productivity.