Physiological Characters Associated with Water-Stress Tolerance Under Pre Anthesis Water-Stress Conditions in Wheat

This study was conducted to evaluate previously identified water-stress tolerance and water-stress susceptible varieties, including Falchetto and Chinese spring (CS) (water-stress tolerant) and Oxley and Flat (water-stress susceptible), for some physiological characters affecting the performance of varieties under water-stress conditions. The results indicated that water-stress tolerant varieties had higher Stomatal Resistance (SR), higher Leaf Relative Water Content (LRWC), higher Vegetative Water Use Efficiency (WUEveg) and higher Vegetative Evapo-transpiration Efficiency (ETEveg) than water- stress susceptible varieties. Varieties with higher LRWC generally had higher SR. This indicates that higher LRWC is, at least in part, due to higher SR. The variety Oxley (water-stress susceptible) showed no significant differences from Falchetto (water-stress tolerance) for stomatal area on both surfaces of the flag leaf but Falchetto had higher number of stomata per unit area and smaller stomata than Oxley. This implies that low frequency of stomata is compensated by high stomatal size. This also indicates that differences in SR between these two varieties are possibly due to differences in stomatal response to water-stress or due to differences in cuticle resistance.