Evaluation of some bread wheat genotypes popular in Saudi Arabia under drought stress

Six bread wheat genotypes were evaluated in three separate irrigation regime experiments to compare the response of agronomic performance and to identify genotypes with high yield potential under drought stress. The first irrigation treatment (I3) was given normal water irrigation (about 7000 m3 ha-1, according to recommendation for Qassim Region). The second (I2) and third (I1) treatments were given 2/3 and 1/3 of water amount of the first treatment, respectively. Factorial experiments in randomized complete block design with three replications were conducted during 2009/2010 and 2010/2011 seasons in the arid environment of central region of Saudi Arabia. Measurements were taken on days to heading, plant height, number of spikes m-2, number of kernels spike-1, 1000-kernel weight and grain yield. The drought susceptibility index (DSI) and water utilization efficiency (WUE) were calculated. The results revealed that effect of irrigation regime was highly significant for all traits, except days to heading. All studied characters were significantly decreased by reducing the amount of irrigation water. Grain yield showed maximum sensitivity as affected by moisture-stress. Means over environments indicated the existence of sufficient genetic variability among the genotypes for all the characters studied. Giza 171 recorded the highest values for most yield characters, while genotype 'Sama' was the lowest for the most yield characters. Giza 171, Sakha 93 and IC-1 recorded highest grain yield and WUE, based on average over irrigation treatments. Giza 171, Sakha 93 and IC-2 can be considered as drought stress tolerant genotypes.