Genetic analysis for phenological and physiological traits in wheat (Triticum aestivum L.) under heat stress environment

An experiment was conducted during rabi season of 2007–08 and 2008–09 by using 50 diverse wheat genotypes and two sowing dates (15 November and 15 December) to assess the genetic variability for phenological and physiological traits under normal and heat-stress environments. Analysis of variance, exhibited highly significant differences at genotypic level for all the traits studied, under normal and heat-stress environments. All the traits expressed significant interaction with environments, indicating that all traits respond to high temperature in different ways in different genotypes. This variability gives sufficient scope for further selection of the traits under consideration. In general, phenotypic coefficient of variation was higher than genotypic coefficient of variation for all the traits, indicating that environments had major role in expression of these traits. Four metric traits viz., number of tillers per meter, biological yield, grain yield and harvest index should moderate heritability (80–90%),while number of seeds per spike, thousand grain weight and cell membrane thermo stability had high heritability (> 90%) coupled with high expected genetic advance. These traits can be utilized as selection criteria for improving the grain yield in the warmer wheat growing areas for terminal heat-stress.