Yield Performance and Stability of Spring Bread Wheat Under Heat-Stress Environments.

Wheat is traditionally cultivated in temperate environments. However due to the increasing demand for food and change in eating habit, wheat cultivation has extended to non-traditional environments including tropical and subtropical hot environments  characterized by high temperature stress throughout most of the growing season. To identify heat tolerant germplasm for such harsh non-traditional wheat environment analytical selection approach utilizing adaptive morpho-physiological traits is practiced in addition to empirical selection. Thus carrying out adaptation yield trails is a major activity for wheat breeding programs targeting such environments. This study was conducted at multilocations where 24 bread wheat genotypes including the commercial cultivars were evaluated in a alpha lattice design trial with three replications. Analysis of variance revealed highly significant differences among genotypes, sites and highly significant genotype X site interaction. Observed mean yields for sites ranged from high to low in a north-south thermal gradient.  Effect of temperature regime on observed yields across north-south gradient is discussed. Additive Main effect and Multiplicative Interaction (AMMI) analysis of genotypic response across sites identified genotypes that exhibited high yield and stability.