Investigation of the Effect of Silicon on Wheat Yield and Water Use Efficiency under Water Stress Conditions

This study was conducted to investigate the effect of silicon on wheat yield and water use efficiency (WUE) in water stress conditions. The study site was Research Farm of Soil and Water Research Institute in Karaj. The experiment was conducted as a randomized complete block design with split plots, in 2018-219 season. The main factor was irrigation at two levels of full irrigation and stress (40% less than wheat water requirement), and the secondary factor including foliar application of potassium silicate at three levels (zero, 2.5 and 5 kg/ha) at three growth stages (shooting, flowering, and grain filling) and soil application of potassium silicate (zero and 20 kg/ha). The results showed that soil and foliar application of potassium silicate increased grain yield, thousand-grain weight, number of seeds per spike, spike length, and height of wheat plant. Reducing irrigation from 100% to 60% of wheat water requirement caused a decrease in grain yield by 8.3%, but the application of potassium silicate compensated for this decrease, such that under drought stress, wheat grain yield with application of 0.005 potassium silicate increased by 30.6% compared to the non-application of silicon. The highest WUE was obtained under water stress conditions and application of 5‰ potassium silicate increased the WUE by 31% compared to non-application. Therefore, in the conditions of water stress, compared to the farmers' practices, foliar application of potassium silicate with a concentration of 5‰ can be recommended during the growth stages of wheat.