Effects Of High Temperature And Waterlogging During Grain Filling On Grain Yield And Quality Formation In Wheat

Wheat grain yield and quality not only under genetic control, but also by the impact of ecological environment and cultivated measures. In the middle and lower Yangtze River region is one of the main wheat part of China, this area of wheat in wheat growth period often with30℃high temperature weather, and grain filling stage of wheat and the wheat drought in the north and south of waterlogged disaster occurs frequently, and the area of Yangtze River in grain filling stage of waterlogging stress duration was a continuous elongated trend in our country. High temperature and waterlogging are major ecological factors which limit grain quality formation during grain filling stage. This article attempts to discuss effect of high temperature and waterlogging on grain yield and quality formation and its physiological and deepen the quality of wheat physiological and ecological and guide cultural management significance in theory and practice in wheat. To explore matters of post-anthesis high temperature and waterlogging on grain yield and quality, a pool culture experiment with winter wheat (Triticum aestivum L.cv Yangmai16) was conducted.During grain filling stage,there are three treatments:(1)the Control (natural growth temperatures and the soil relative water content was maintained at70-80%);(2) post-anthesis waterlogging (natural growth temperatures and maintaining a1-2cm water layer above the soil for7days);(3) post-anthesis high temperature(diurnal temperature is5℃higher than that of control for7days and the soil relative water content was maintained at70-80%). The performances of flag leaf photosynthesis, chlorophyll fluorescence traits, antioxidant enzymatic activity and carbon and nitrogen metabolism were then investigated. And further studies in grain yield and quality physiology of wheat. The main results were as follows:1. High temperature and waterlogging stress during grain filling reduced flag leaf antioxidant capacity in wheatCompared with the control, high temperature and waterlogging treatments reduced effectively antioxidant capacity in wheat flag leaf during grain filling,by decreasing activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and soluble protein content; but malondialdehyde (MDA) content was significantly increased under these stresses, and also had the same trend in chloroplasts:activities of superoxide dismutase (SOD) and peroxidase (POD) decreased comparing with the control, and these treatments exhibited the pattern of higt temperature> waterlogging> CK; however, malondialdehyde (MDA) content and O2-generating rate were significantly increased under these stresses comparing with the control. Malondialdehyde (MDA) content and O2-. generating rate in mitochondrion exhibited the same trend with chloroplasts, thereby remarkably reduced flag leaf antioxidant capacity in wheat during grain filling stage2. High temperature and waterlogging stress during grain filling affected flag leaf photosynthetic capacity, carbon and nitrogen accumulation and redistribution and grain yield in wheatCompared with the control, high temperature and waterlogging treatments significantly reduced transpiration rate(Tr), stomatal conductance(Cs), SPAD value and photochemical conversion of absorbed light energy via maitainance of high PS Ⅱ maximum photochemical efficiency (Fv/Fm). actual photosynthetic efficiency (ΦPS Ⅱ). thereby remarkably reduced flag leaf photosynthetic capacity in wheat during grain filling stage. Compared with the control, high temperature and waterlogging treatments not only reduced effectively soluble sugar and sucrose content and free amino acid content in vegetative organs and grain, but also significantly reduced the1000-kernel weight, biomass, harvest index, and consequently reduced grain yield of wheat. Post-anthesis waterlogging treatment was significantly reduced NRA、NRR、NPA and NCP, but it improved CNR.3. High temperature and waterlogging stress during grain filling affected grain and flour quality in wheatCompared with the control plants, furthermore, post-anthesis high temperature treatment significantly increased the protein, albumin, globulin, gliadin protein content and falling number, but significantly reduced the content of glutenin, glu/gli, GMP, HMW-GS, total starch, amylopectin content, sedimentation volume and flour pasting temperature, and also significantly reduced flour peak viscosity, trough viscosity, final viscosity, setback and peak time. In addition, post-anthesis waterlogging treatment significantly enhanced gliadin content, falling number, but it decreased albumin, glutenin content, glu/gli, GMP. HMW-GS, amylopectin and wet gluten content, but waterlogging treatment also significantly reduced flour final viscosity, setback, peak viscosity and pasting temperature.In conclusion, high temperature and waterlogging treatments reduced the photosynthetic and antioxidant capacity in wheat flag leaf and regulated effectively carbon and nitrogen metabolism during grain filling. Finally, high temperature and waterlogging treatments reduced markedly grain yield, compared with the control plants, while it affected grain quality.