INHERITANCE OF HEAT TOLERANCE IN BREAD WHEAT (TRITICUM AESTIVUM L.)

Abstract

Heat is a serious production challenge to wheat such that more than 50% of the cultivated area experiences a high temperature (HT) stress leading to a dramatic loss in yield every year Mitigating this constraint requires development of heat tolerant wheat genotypes. The objective of this study was determining the mode of gene action governing the inheritance heat tolerance in wheat. Six genotypes comprising of three heat tolerant and three heat susceptible were crossed to generate three sets of crosses: 29872 x 30119 (cross I), Tesfa x 29642 (cross II) and 30098 x 29988 (cross III). The F₁ progenies of each cross were advanced to F₂. The parents, F₁ and F₂ of each cross were evaluated under heat stress condition (27-37⁰C) at Research Farm, Federal University of Lafia in randomized complete block design with two replications. Crop management followed the recommended agronomic practices for wheat production. Data were collected on days to heading, days to maturity, length of spike (cm), number of spikelets per spike, grain yield (g), 1000 grains weight (g), biomass (g), relative chlorophyll content, canopy temperature (⁰C), membrane thermal stability (%) and relative cell injury (%). The results of analysis of variance revealed significant (p≤0.05) differences among the generations for all traits studied except canopy temperature (Zadok 77) and length of spike in cross indicating variation among generations for the traits providing adequate scope for selection.  The results of C scaling test were significant (p≤0.05) for heat and other agronomic traits suggesting inadequacy of the additive-dominant model. This may imply the use of generation mean analysis to fully understand the mode of inheritance for heat tolerance in wheat.