Effects Of Exogenous Trehalose On Wheat Yield And Sugar Components Under High Temperature Stress At Filling Stage

With global warming,the risk of high temperature stress during the grain filling period is increasing.High temperature weather occurs frequently during the grain filling period of wheat in the Huang-Huai-Hai region,which has a serious impact on wheat yield.Trehalose（TRE）is a non-reducing sugar,which can protect plants from abiotic stress under stress conditions,but whether it can alleviate the high temperature damage of wheat is still unclear.In order to clarify the effect of TRE on wheat yield and carbohydrate distribution under high temperature stress during grain filling stage,in the two wheat growing seasons of 2020—2022,the wheat varieties selected in the previous experiment:Huaimai 33（HM33）,Longke 1109（LK1109）,Wankenmai 1720（WKM1720）,Fanmai 5（FM5）,Annong 1589（AN1589）,Yannong 999（YN999）,Anke157（AK157）and Tainong 19（TN19）were used as test materials.The effects of different concentrations of TRE on wheat yield formation and sugar metabolism under high temperature stress at grain filling stage were explored through dry matter accumulation and distribution,grain filling,photosynthetic characteristics,senescence characteristics and sugar metabolism,in order to provide theoretical basis and technical guidance for high temperature resistance production of winter wheat.The results show that:（1）Exogenous pre-spraying TRE could alleviate the decrease of wheat yield under high temperature stress during grain filling stage,and the best concentration was 15mmol·L^-1.Exogenous TRE pre-spraying increased the 1000-grain weight and yield of wheat under high temperature stress at filling stage,increased the grain weight of strong and weak grains at different panicle positions,increased the distribution of dry matter accumulation in grains,and slowed down the decrease of grain filling rate.Exogenous TRE spraying treatment increased the maximum filling rate and average filling rate of wheat compared with non-spraying treatment,and increased the filling rate and grain accumulation in the gradual increase period,rapid increase period and slow increase period.Exogenous TRE can improve the grain filling ability of wheat under high temperature stress during grain filling stage,which is beneficial to the increase of grain weight and ultimately alleviate the decrease of yield under high temperature stress.Pre-spraying 15 mmol·L^-1 TRE at anthesis stage had the best mitigation effect on wheat yield loss under high temperature stress at filling stage.（2）Exogenous pre-spraying TRE can alleviate the damage of high temperature stress on wheat photosynthetic organs during grain filling stage,which is beneficial to improve the photosynthetic production capacity of flag leaves.Exogenous TRE pre-spraying reduced the content of malondialdehyde（MDA）in flag leaves of wheat under high temperature stress at filling stage,increased the activities of superoxide dismutase（SOD）,peroxidase（POD）and catalase（CAT）,and alleviated the membrane lipid peroxidation of flag leaves and the damage of high temperature stress to chloroplasts.Under the condition of exogenous pre-spraying TRE,the leaf area,chlorophyll relative content（SPAD）,maximum photochemical efficiency（F_v/F_m）,net photosynthetic rate（P_n）,stomatal conductance（G_s）and transpiration rate（T_r）of wheat flag leaf were also significantly increased,which indicated that exogenous TRE could slow down the decrease of photosynthetic capacity of flag leaf under high temperature stress after anthesis,which would be beneficial to promote the formation and accumulation of grain yield after anthesis.（3）Exogenous TRE stimulated the sugar metabolism ability of wheat plants under high temperature stress during grain filling stage,providing a material basis for grain yield.Exogenous TRE pre-spraying increased the contents of sucrose,soluble sugar and starch in flag leaves under high temperature stress at filling stage.At the same time,exogenous TRE spraying can improve the ability of wheat plants to resist high temperature stress by increasing the content of TRE,fructose and glucose in flag leaves of wheat under high temperature stress at filling stage.This indicated that exogenous TRE could alleviate the decrease of wheat yield under high temperature stress during grain filling stage by improving the sugar metabolism ability of wheat.In summary,exogenous trehalose can effectively alleviate the damage of high temperature stress to wheat,improve the photosynthetic performance of wheat flag leaves after anthesis,delay the senescence of wheat flag leaves after anthesis,and maintain a high level of assimilation products and sugar metabolism-related carbohydrates after wheat anthesis,which is conducive to promoting the formation and transformation of grain starch in the later stage,and effectively alleviating the reduction of wheat yield under high temperature stress during grain filling stage.