Effect of deficit irrigation with brackish water on growth and yield of winter wheat and summer maize

Pot and field experiments on deficit irrigation with brackish water were conducted. The objective of the experiments was to substitute fresh water of irrigation with brackish water, which could relieve water shortage in the Bohai Rim of China. The effects of deficit irrigation with brackish water on winter wheat yield, yield components and physiological characters were studied. The yield of the later crop, summer corn, was investigated too. The pot experiment showed that the order of irrigation for optimum wheat yield was double irrigation > single irrigation > rain-fed. Change in yield was mainly caused by the 1000-gain weight variation. The effect of salt levels of irrigation water on wheat yield was insignificant. In the field experiment, four treatments were analyzed — no irrigation after winter (A0), irrigation at jointing stage with fresh water (A1), 2 g·L^-1 (A2) and 4 g·L^-1 (A3) brackish water irrigation. The field experiment showed that brackish water irrigation decreased excise-leaf water loss, increased specific leaf weight and leaf area of winter wheat. No significant change was observed in kernel number per spike and spike number. The 1000-grain weight, however, decreased under brackish water irrigation. The order of yield for winter wheat under the treatments was A2>A3>A1> A0. Salt content in the 0~40 cm soil layer was enhanced under brackish water irrigation. It increased more obvious under higher salt concentration of irrigation water. Among the cations in the 0~40 cm soil layer, K⁺ + Na⁺ increase was most significant. Although there was no irrigation during the growth period of summer maize, maize yield under A2 and A3 treatments dropped by 11.8% and 18.8%, respectively, compared with A1. The yield drop in A2 and A3 was due to the accumulation of salts in the soil during the growth period of winter wheat. Yield under A3 was 8.0% lower than that under A2. The order of the total yield for winter wheat and summer maize was A2>A1>A3>A0. The results suggested that irrigation with 2 g·L^-1 brackish water had no significant effect on annual yield of winter wheat and summer maize in the winter wheat/summer maize double cropping system.