Evaluation of Three Physiological Traits for Selecting Drought Resistant Wheat Genotypes

Physiological traits are receiving increasing attention as screening tools for drought resistance.Two field experiments were conducted in 1998 at the Experimental Station of College of Agriculture, Shiraz University at Badjgah, to evaluate the effectiveness of leaf water potential, leaf osmotic potential and canopy temperature in screening resistant bread wheat (Triticum aestivum L.) genotypes. Nine wheat cultivars consisting of drought resistant, intermediate and susceptible genotypes were grown in two randomized complete block designs with three replications. The experiments only differed with respect to their irrigation regimes. Leaf water potentials and leaf osmotic potentials at three developmental stages -stem elongation, booting and flowering - under water stress conditions,and canopy temperature in non-stress conditions could discriminate between resistant and susceptible cultivars. Although the drought susceptibility index could partly discriminate between resistant and susceptible cultivars, it was not evaluated as a reliable index. The linear regression of grain yield on each trait was determined. The linear regressions of grain yield on leaf water potential; leaf osmotic potential and canopy temperature confirmed the above results