Effects Of High Temperature After Anthesis On Grain Development And Germination Characteristics Of Wheat

[Objective]This study explored the effect of high temperature after anthesis on the morphology,cytology,endogenous hormone content and germination characteristics of wheat grain at different developmental stages,preliminary understanding of the physiological mechanism of wheat grain response to high temperature stress after anthesis,to provide some theoretical guidance for wheat breeding with high temperature tolerance.[Method]In this study,Xinchun 11 the main cultivar in Xinjiang was planted in the greenhouse of the Agricultural College of Shihezi University in 2016.It was treated with high temperature on 5⁸ days after anthesis,take samples on 10 days,15 days,20 days,20 days,25 days and 30 days after anthesis,respectively.The fresh and dry weight of grain was observed at each stage after anthesis,and grain slice was made to observe the development of pericarp and embryo,and to detect the change of endosperm cell number.The endosperm cell death was observed by Evans blue staining.The contents of abscisic acid,auxin,gibberellin and gibberellin?GA₃?in wheat grain at different stages after anthesis were detected,and the effect of post-anthesis heat on endogenous hormone content in wheat grain was clarified.The germinating experiments were carried out after high temperature treatment after anthesis and untreated seeds,and the effects of high temperature after anthesis on seed germination rate,germination potential,seed vigor,electrical conductivity and so on were observed.The changes of amylase,catalase?catalase?and peroxidase?POD?during seed germination were detected.[The main results were as follows]:?1?High temperature after anthesis increased grain fresh weight,dry weight and endosperm cell number at the early stage of grain development in wheat by 6.71%,9.63%and 8.23%,respectively,and promoted cell death and embryonic tissue development in caryopsis.In the middle and late stages of grain development,grain development was hindered,and the final grain weight and endosperm cell number were reduced by 4.27%and 9.74%,respectively,which were significantly lower than the control.Simultaneously,the development of pericarp and embryonic tissue was inhibited,and the process of endosperm PCD was aggravated.High temperature after anthesis significantly promoted early grain development of wheat,but inhibited late grain development.?2?High temperature after anthesis treatment advanced the time of the endogenous GA3 and IAA content of wheat grain to the maximum value,and it could significantly promote the accumulation of endogenous GA3 and IAA in the early grain filling stage.On the 10 days after flowering,the content of GA3 and IAA of wheat grain after high temperature treatment was 46.95%and 10.32%higher than that of the control,respectively,but with the grain filling,the content of GA3 and IAA decreased significantly,but the high temperature treatment increased the endogenous ABA content of wheat grain.Correlation analysis showed that hormones had a regulatory effect on grain fresh weight and endosperm cell proliferation,indicating that high temperature after anthesis significantly affected the endogenous hormone content of wheat kernels,regulating GA3,IAA and ABA hormone concentrations,regulating grain development,responding to high temperature stress.?3?High temperature after anthesis treatment significantly decreased the germination rate and germination potential of wheat,and the length,fresh weight,root length and root fresh weight of the seedlings decreased significantly;meanwhile,the?-amylase and?-amylase during seed germination were significantly decreased.Both total amylase activity and POD and CAT activity were significantly reduced.The correlation analysis showed that the high temperature after anthesis resulted in the decrease of related enzyme activity in the grain,which resulted in the decrease of seed vigor and weakened the growth of seedlings.[Conclusion]In summary,high temperature after anthesis has affected the development and germination characteristics of wheat grain to a certain extent,aggravated premature aging of wheat grain,reduced seed vigor and weakened seedling growth.Therefore,in order to reduce the effect of high temperature on wheat yield and quality,it is very important to prevent high temperature in agricultural production.