Abstract:
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
