Effects Of High Temperature During Grain Filling On Flag Leaf Physiology And Grain Yield Of Wheat

In order to investigate the physiological response of wheat to high temperature stress during grain filling stage,clarify the different characteristics of physiological indexes of different wheat varieties under high temperature stress during grain filling stage and support theoretical guidance for breeding of heat-resistant wheat varieties and high-yield stable wheat varieties in Huang-Huai-Hai region,this study used 16 wheat varieties which are usually planted in Huang-Huai-Hai area as experimental materials,then the soluble protein,soluble sugar,superoxide dismutase,malondialdehyde,catalase,SPAD of flag leaves,1000-grain weight and yield were determined after high temperature stress during grain filling stage,finally utilized principal component analysis and cluster analysis to evaluate the heat resistance of different wheat varieties.At the same time,we studied the variation characteristics of heat resistance index of wheat varieties with different heat resistance and discussed the response of flag leaf physiology and grain filling to high temperature stress in wheat with different heat resistance during grain filling stage to provide theoretical basis for exploring the mechanism of heat tolerance and breeding heat-resistant varieties.The main conclusions are as follows :1.After high temperature stress during grain filling stage,the content of enzyme-soluble protein in flag leaves of wheat increased firstly and then decreased,and reached the highest level 16 days after anthesis;high temperature stress could slow down the content of soluble protein in flag leaves of wheat.The content of enzyme-soluble sugar in flag leaves of wheat increased firstly and then decreased.After high temperature stress during grain filling stage,the activity of Superoxide Dismutase in flag leaves of wheat increased firstly and then decreased,and reached the highest level 24 days after anthesis.The results showed that the activity of superoxide dismutase in flag leaves of wheat increased firstly and then decreased under high temperature stress.After high temperature stress during grain filling stage,the content of Malondialdehyde in flag leaves of wheat increased firstly and then decreased,and reached the highest level 24 days after anthesis,and then it started falling again.2.The soluble protein content,soluble sugar content,content of malondialdehyde in flag leaves and1000-grain weight of grain are larger in new comprehensive indexes of principal component analysis.These results indicated that they play an important role in evaluating the heat resistance of wheat and can be used as an index for evaluating the heat resistance of wheat.3.According to the comprehensive evaluation,the results are obtained: Jimai22,Shimai19 and Zhengmai366 belong to highly resistant varieties;Zhoumai18,Zhengmai7698,Liangxing99,Huaimai33,Shimai22,Anong0711 are moderately heat-resistant varieties;Zhoumai22,Yumai49-198,Shannong20,Lankao198,Pingan 8,Xinong979 and AiKang58 are not heat-resistant varieties.