| Climate change may cause a slight increase in air temperature,which increases accumulated temperature change during wheat growing season,but there are few reports on the physiological effects of increase in temperature during early grain development.In this study,PO film was used to mimic the natural warming,and the effects of early warming after anthesis on the physiological characteristics of winter wheat leaves and grain development were studied in 2018-19.The effect of early temperature increase was implemented using PO film mulching method to achieve temperature increase(range of temperature increase is 1-3℃)for 10 days(0-10 days after anthesis)from 9:00 a.m.to 5:00p.m.every day.The wheat varieties are Annong 0711 and Yannong 19,widely sown in south Huang-Huai-Hai.The changes of chlorophyll content,photosynthetic parameters,MDA content,antioxidant enzyme activity,sucrose,fructose and reducing sugar content in flag leaf,grain shape,fresh and dry weight,yield and yield components as well as grain quality were analyzed.The purpose of this study is to study the effect of climate warming on the early post anthesis stage of wheat.The mechanism of the influence of climate warming on the growth and development of flag leaf and grain of wheat was explored,which provided theoretical basis and technical guidance for the cultivation and management of wheat under the condition of climate temperature rising in the future.At present,the main research results are as follows:i.Compared with the control,the content of chlorophyll in flag leaf of winter wheat decreased significantly after the treatment of small increase of temperature in the early stage after anthesis,and the temperature increase also led to the decrease of net photosynthetic rate and stomatal conductance,the increase of transpiration rate and intercellular carbon dioxide concentration,which was related to the decrease of water use efficiency under temperature stress.The increase of temperature reduced the content and activity of protective enzymes related to flag leaf,increased the content of malondialdehyde and accelerated membrane lipid peroxidation,which indicated that flag leaf related properties were decreasing,flag leaf senescence was ahead of time,and functional period was shortened.Increasing temperature reduced the content of sucrose,fructose and reducing sugar in flag leaf,which showed that the production and accumulation of photosynthetic products in flag leaf decreased,which was not conducive to plant growth and development.ii.Through the analysis of the morphological development of superior and inferior grains as well as the changes of fresh and dry weight of superior grains,it was found that the growth and development of wheat grains were affected by a small increase of temperature in the early stage after anthesis.The length,width and thickness of wheat grain were lower than that of the control.The comparative analysis of the shape of wheat superior and inferior grains showed that different varieties superior and inferior grains had different influence on the temperature increase.The decrease degree of the superior grain of Annong 0711 was lower than that of the inferior grain,while that of Annong 0711Yannong19 was opposite.Compared with the fresh and dry weight of the dominant grain,the increase of temperature can significantly reduce the fresh and dry weight of the grain.However,the results were not significant.iii.Through the analysis of the content of sucrose,fructose and reducing sugar in winter wheat grain,it was found that the increase of temperature decreased the content of non structural carbohydrate such as sucrose,fructose and glucose needed for grain growth and development.Through the analysis and Research on the distribution rate of dry matter of the components in the upper part of wheat,it was found that the increase of temperature affected the distribution and transport of dry matter of the components in the upper part of wheat.The distribution rate of dry matter in leaves and ears was lower than that in the control,while that in Culm and sheath was higher than that in the control.The results showed that a small increase of temperature in the early stage after anthesis affected the coordination among "source","sink" and "flow".iv.Through the analysis of grain yield,components and quality of winter wheat,it was found that the increase of temperature in the early stage after anthesis would significantly reduce the 1000 grain weight of wheat,and the grain weight of Annong 0711 and Yannong19 decreased by 5.43% and 7.34%,respectively.The increase of temperature also decreased the protein content,water absorption and bulk density,but had no significant effect on the stability time,formation time and percentage of wet gluten.To sum up,after anthesis,a small increase in temperature in the early stage of winter wheat affects the physiological characteristics such as flag leaf photosynthesis;to a certain extent,it affects the development of wheat grain morphology,significantly reduces the1000 grain weight,and affects the yield and quality. |
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