Effect of Drought Stress on Photosynthetic and Physiological Characteristics of Flag Leaves of Different Wheat Varieties at Filling Stage

PENG Chaojun; HUA Xia; WANG Songfeng; GAO Chong; DONG Haibin; HU Lin

doi:10.15933/j.cnki.1004-3268.2025.02.005

Abstract：The drought-resistant wheat variety Zhengmai 1860,its parents,and Zhoumai 18(control)were used as materials.The gas exchange parameters,chlorophyll fluorescence characteristics,antioxidant enzyme activities,osmotic adjustment substances contents in flag leaves,and water use efficiency of different wheat varieties were studied under drought treatment(irrigation only at the jointing stage during the entire growth period),so as to provide valuable insights for optimizing water-efficient wheat cultivation,developing drought-resistant cultivars,and advancing water-saving breeding programs.The results showed that,under drought stress,the net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr)and maximum photomassive efficiency(Fv/Fm),potential photochemical activity(Fv/Fo),actual photomassive efficiency(ФPSⅡ),and electron transfer rate(ETR)of PSⅡ of the flag leaf of Zhengmai 1860 were significantly higher than those of Zhoumai 18,and the intercellular CO2 concentration(Ci)was significantly lower than that of Zhoumai 18,followed by Zhoumai 22;The activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT),and the contents of soluble protein,soluble sugar and proline in the flag leaf of Zhengmai 1860 were significantly higher than those of Zhoumai 18,and the content of malondialdehyde(MDA)was significantly lower than that of Zhoumai 18,followed by Zhoumai 22;The yield and water use efficiency of Zhengmai 1860 were significantly higher than those of Zhoumai 18,which was mainly due to the significant improvement of the thousand-grain weight and the number of grains per spike,and followed by Zhoumai 22.In conclusion,Zhengmai 1860 enhances antioxidant enzyme activity,and osmotic adjustment capacity under drought stress at filling stage,protects the photosynthetic electron transport process of PSⅡ,alleviates the degree of nonstomatal restriction and membrane lipid peroxidation,and maintains higher Pn at filling stage,thus obtaining higher yield.