Abstract:

The effects of different degrees of drought stress on antioxidant enzyme activity, malondialdehyde(MDA)content,photosynthetic characteristics,and yield composition of wheat were investigated to provide a theoretical basis and technical support for optimizing water-saving production of wheat.From 2023 to 2025,four soil water gradients of heavy drought(I-hd),moderate drought(I-md),mild drought(I-fd)and suitable water content(I-sm)were set up in the Longkou Experimental Station of Shandong Academy of Agricultural Sciences.The antioxidant enzyme activity,MDA content,photosynthetic characteristics and grain yield composition of wheat under different drought stress were systematically analyzed.The results showed that compared with moderate and heavy drought,mild drought and suitable water were beneficial to optimize spike number,grain number per spike and 1000-grain weight,thus significantly increasing grain yield,and the average grain yield in two years increased by 11.1%—51.0%.The activities of antioxidant enzymes such as superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)were significantly increased at each growth stage under mild drought and suitable water,and the MDA content in leaves was significantly decreased at each growth stage,which played an important role in reducing the degree of cell membrane lipid oxidation and delaying plant senescence.The leaf area index(LAI),chlorophyll relative value(SPAD value)and net photosynthetic rate(Pn)of leaves at booting,flowering and mid-filling stages were maintained at a high level under mild drought and suitable water conditions,which provided a physiological basis for the improvement of photosynthetic rate,while the above indices were significantly reduced during the whole growth period under moderate and severe drought conditions.The results of correlation analysis showed that the activities of antioxidant enzymes(SOD,POD,CAT)were significantly negatively correlated with MDA content,and significantly positively correlated with photosynthetic characteristics(LAI,SPAD,Pn)and yield components(spike number,grain number per spike,1000-grain weight),which provided physiological guarantee for maintaining higher photosynthetic capacity.In summary,both mild drought and suitable water significantly increase the activities of antioxidant enzymes such as SOD,POD,and CAT in leaves at each growth stage,reduce the content of harmful substances such as MDA,and optimize LAI and SPAD values to improve the photosynthetic rate of leaves.The final grain yield increased by 11.1%—51.0%.However,there was no significant difference in grain yield,antioxidant enzyme activity and photosynthetic characteristics between mild drought and suitable water.Therefore,it is concluded that under mild drought conditions,high and stable yield of wheat can be achieved by optimizing photosynthetic characteristics and leaf antioxidant capacity,which provides a reliable practical approach for water-saving crop production.

Key words: Wheat, Drought stress, Yield, Antioxidant enzyme, Photosynthetic characteristic

CLC Number: 

• S512.1小麦