Effects of Different Saline Water Irrigation on Yield, Physiological and Biochemical Traits of Winter Wheat

Abstract

【Objective】 The purpose of the study is to determine the appropriate irrigation water salinity threshold for winter wheat. Correlation analysis was conducted to find out the important growth, physiological and biochemical indexes related to wheat yield under different saline water irrigation. 【Method】 The pots experiment was conducted in 2019/20 season with two winter wheat varieties of SM22 and XY60 and four irrigation water salinities of 1 g/L, 3 g/L, 5g/L and 7 g/L. Irrigation water salinity with 1 g/L was taken as the control (CK). During the experiment, we measured the changes in yield, of wheat, as well as its physiological and biochemical traits in each treatment. 【Result】 The yield of both wheat varieties decreased as irrigation water salinity increased though at different rates. Compared with the CK, irrigating with saline water at concentration of 3, 5 and 7 g/L reduced the yield of SM22 by 3.23%, 24.19% and 51.61% respectively, and the yield of XY60 by 9.88%, 35.80% and 51.85% respectively. In terms of plant traits, increasing irrigation water salinity reduced the spike number and 1 000-kernel weight, plant height, flag leaf area, above- and below-ground biomasses, stomatal conductance, transpiration rate, net photosynthesis rate, chlorophyll content (SPAD) of the flag leaf, K+/Na+, Ca2+/Na+ and Mg2+/Na+ ratios in the leaves during grain-filling stage. All these reductions were at significant level. In contrast, it increased the proline content and Na+ content in leaves during the grain-filling period at significant level. In all treatments, the wheat yields were to be positively correlated to the following traits at significant level (p<0.05): 1 000-kernel weight with r=0.991, plant height with r=0.955, aboveground biomass with r=0.961, root biomass with r=0.835, SPAD with r=0.943, leaf K+/Na+ with r=0.908; and negatively correlated with the following traits at significant level (p<0.05): leaf proline content with r=-0.838, and Na+ content with r=-0.861. 【Conclusion】 The response of yield, growth, physiological and biochemical traits for the two wheat varieties to different irrigation water salinity had the similar trend. When irrigation water salinity was 7 g/L, there was significantly difference for the grain yield compared to the CK. Irrigation water salinity threshold of winter wheat was 3~5 g/L. In terms of traits which affect the ultimate yield, the1 000-kernel weight was the most important yield trait; plant height, above- and below-ground biomasses were the most important growth traits; flag leaf SPAD was the most important physiological trait; leaf proline content, Na+ content and K+/Na+ were the most important biochemical traits.

Keywords

• saline water irrigation
• winter wheat
• grain yield
• physiological and biochemical traits
• irrigation water salinity threshold