Genetic Variability and Performance of Bread Wheat (Triticum aestivum L.) Genotypes under High Temperature Environments of Ethiopia

Abstract

This study was conducted during May to December, 2022 at Kulumsa and Melkassa, in Ethiopia, evaluated 49 CIMMYT-introduced genotypes including the check variety across two locations using an alpha lattice design. The Combined analysis of variance revealed highly significant genetic variability for most of the traits, including grain yield (GYLD), thousand kernel weight (TKW) and hectoliter weight (HLW).Genotypes EBW222059, EBW222088 and EBW222079 were the top yielders, consistently outperforming the check. High genotypic (GCV) and Phenotypic (PCV) coefficients of variation for GYLD (22.24% and 24.42%) and TKW (13.38% and 15.32%) at Kulumsa indicated a strong genetic base for improvement. Very high broad-sense heritability for grain yield (83%) and days to heading (92%), coupled with high genetic advance as a percent of mean (GAM) for grain yield (41.72%), suggested the predominance of additive gene action, making phenotypic selection highly effective. However, maturity traits and plant height showed significant environmental influence, rendering direct selection for these traits ineffective. Correlation analysis confirmed that grain yield was strongly and positively associated with TKW and HLW at both genotypic and phenotypic levels. These results demonstrated that selecting for heavier, denser grains was a reliable strategy for yield enhancement. The study concluded that the identified elite genotypes should advance to multi-environment stability trials, while TKW and HLW should be prioritized as key selection markers to accelerate the development of high-yielding, adaptable wheat varieties. Thus, genetic variability in these genotypes could be exploited to enhance bread wheat yields under high-temperature conditions of Ethiopia.