The Effect of Deficit Irrigation and Saline Water Treatments on Growth and Yield Responses of Sirvan Bread Wheat Cultivar

Today, maintaining the quantity and quality of irrigation water are the most critical challenges in the agriculture system, especially in arid and semi-arid regions of the world. Accordingly, to evaluate the growth and yield responses of bread wheat (Sirvan cultivar) to different levels of deficit irrigation and water salinity, a factorial experiment was conducted in a randomized complete block design with three replications in the Research Field of Agriculture Faculty of the University of Birjand, at Birjand (east of Iran) during the growing seasons of 2016-2017 and 2017-2018. The experimental treatments included irrigation at five levels (125, 100, 75, and 50% of wheat water requirement and rain-fed with two supplementary irrigation at the first growing season) and saline water at two levels (1.6 dS/m and 6 dS/m). The results showed that growth characteristics, yield components, biological yield, and grain yield were affected by deficit irrigation water and saline water. These treatments significantly reduced all of the measured traits. The lowest leaf area was observed in rain-fed with 6 dS/m saline water treatment, which suppressed this trait by 61% compared to 125% water requirement with 1.6 dS/m saline water treatment. The highest and the lowest biological yield and grain yield were observed in 125% water requirement with 1.6 dS/m saline water and rain-fed with 6 dS/m saline water treatments, respectively. Non-significant differences were observed in biological and grain yield between 125% water requirement with 1.6 dS/m saline water and 100% water requirement with 1.6 dS/m saline water treatments. Biological yield and grain yield were decreased in rain-fed with 6 dS/m saline water treatment compared to 125% water requirement with 1.6 dS/m salinity treatment by 72% and 88%, respectively. Results of this study showed that although the greatest amounts of yield attributes were obtained upon using the 125% water requirement treatment, but these attributes were not significantly greater than the 100% water requirement treatment. Consequently, in areas with scarce water and saline water (6 dS/m), reliance on the 75% water requirement with 6 dS/m saline water and 100% water requirement with 1.6 dS/m saline water treatments may suffice to achieve an acceptable grain yield and to save water under saline water condition.