wheat deficit irrigation by water depletion and length of sprinkler irrigation

this research was conducted at torogh agricultural research station in khorasan-e razavi province to determine the impact of irrigation cutoff at different growth stages and percentage of water use on the yield and water use efficiency (wue) of wheat cultivars using sprinkler irrigation. the study was done from 2006-2008. the experimental design was a randomized complete block design with a strip split plot layout and three replications. the three vertical plots were for irrigation (70%, 85%, 100% of plant requirement), the three horizontal plots were for irrigation cutoff point (full irrigation, irrigation cutoff at stem elongation, cutoff at pollination) three wheat cultivars (alvand, toos, gaskozhen) were the subplots. the yield means at 70%, 85% and 100% water consumption were, respectively, 3182, 4639, and 4748 kg/ha. water consumption of 85% and 100% fell into statistical group a. the highest value for wue was 1.849 kg/m3 at 85%, followed 1/389 kg/m3 for 70%, and 1.618 kg/m3 for 100%. the irrigation cutoff treatment showed significant differences (p≤ 0.05) for grain yield and wue. full irrigation showed the highest grain yield (4557 kg/ha) and irrigation cutoff at stem elongation and cutoff at pollination actually decreased yield to 4195 and 3817 kg/ha, respectively. full irrigation and irrigation cutoff at stem elongation fell into statistical group a. cutoff at stem elongation had the highest wue (1.778 kg/m3). combined analysis showed that wheat cultivar had a significant effect on grain yield and wue. alvand cultivar had the highest yield (4447 kg/ha) and wue (1.718 kg/m3). the results showed that, where water shortage was not an issue, full irrigation produced the best results. in areas of water shortage, 85% irrigation using the cutoff at stem elongation method is recommended for the best results in yield, water consumption and wue.