| High temperature and waterlogging in the middle and later growing season are the major limiting factors for winter wheat (Triticum aestivum L.) yield and quality improvement in the Southern Huanghuai and Yangtze Valley region of China. Along with the global climate change, both the magnitude and frequency of high temperature and waterlogging are predicted to increase. Nitrogen is one of necessary macro-nutrient for the wheat growth and development. Reasonable application of nitrogenous fertilizers is an important way to alleviate the negative effects of stress, regulate crop growth and development and improve its assimilation capacity. Field experiments with ’Yannong19’(Triticum aestivum L.) by pot method were conducted to investigate the effects of high temperature and waterlogging on physiology and ecology, yield, quality of winter wheat and its nitrogen management in continuous growing seasons from2010to2012in order to provide basic theory for high yield cultivation technology to alleviate high temperature stress, waterlogging stress and senescence of winter wheat by spraying foliar nitrogen in later growth season in the Southern Huanghuai and Yangtze Valley region of China. The main contents and results were below:1Effects of transient high temperature and waterlogging after anthesis on physiology of winter wheat and nitrogen management:(1) Compared with control, high temperature stress, waterlogging stress, high temperature+waterlogging double stress after anthesis all increased degree of membrane lipid peroxidation, resulting in activities of SOD, POD, CAT of winter wheat flag leaf increasing slightly briefly and soon dropping significantly and MDA contents under each adverse stress being always higher than those of control, accelerating plant senescence. Each adverse stress after anthesis decreased the wheat root activities, chlorophyll contents, Pn, Gs of winter wheat flag leaf and their Ci rised continually. High temperature stress decreased wheat flag leaf Tr significantly after the briefly rise and waterlogging stress and high temperature+waterlogging double stress both decreased it continually.(2) There were significant interactions between high temperature and waterlogging and high temperature deteriorated the negative effects of waterlogging. According to degree of negative effects in indexes of physiology in winter wheat, the order was waterlogging+high temperature> waterlogging> high temperature. Negative effects of each adverse stress in grain formation stage were higher than those of in milk-ripe stage.(3) Spraying foliar nitrogen alleviated negative effects of each adverse stress.(4) The change trends of Ci and Pn in the flag leaf were opposite in the experiment, which indicated that the factors affecting photosynthesis should be non-stomatal factors.2Effects of transient high temperature and waterlogging after anthesis on grain filling characteristics and yield components of winter wheat and nitrogen management:(1) Be consistent with changes of physiological indexes, transient high temperature stress, waterlogging stress, high temperature+waterlogging double stress after anthesis all significantly reduced1000-grain volume, grain filling rate, grain filling duration,1000-grain dry weight, grains per spike and yield of winter wheat, but had no significant effect on spikes.(2) There were significant interactions between high temperature and waterlogging and high temperature deteriorated the negative effects of waterlogging. According to degree of negative effects in indexes of yield components in winter wheat, the order was waterlogging+high temperature> waterlogging> high temperature. Negative effects of each stress in grain formation stage were higher than those of in milk-ripe stage.(3) Spraying foliar nitrogen improved1000-grain volume, grain filling rate, grain filling duration,1000-grain dry weight, and yield of winter wheat，but had no significant on spikes and grains per spike.(4) According to grey correlations between yield and grain filling parameters of winter wheat, the relationships with grain filling rate parameters were more significant than those with grain filling duration parameters and each treatment affected yield of winter wheat mainly by affecting grain filling rates in middle and later grain filling stages.3Effects of transient high temperature and waterlogging after anthesis on grain protein synthesis and accumulation of winter wheat and nitrogen management:(1) High temperature stress after anthesis increased slightly activities of flag leaf GS, grain GPT in winter wheat first and soon dropped significantly and waterlogging stress, high temperature+waterlogging double stress both decreased them continually. High temperature reduced protein accumulation, ratio of Glu/Gli, while improved protein content and each protein ingredient content. Waterlogging reduced protein accumulation, protein content and each protein ingredient content, ratio of Glu/Gli. High temperature+waterlogging double stress improved gliadin content, reduced protein accumulation, glutelin content, ratio of Glu/Gli, had no significant effect on contents of albumin, globulin.(2) The interactions between high temperature and waterlogging of flag leaf GS, grain GPT, protein accumulation were significant but those of protein content and each protein ingredient content, ratio of Glu/Gli were not significant. According to degree of negative effects on indexes of grain protein synthesis in winter wheat, the orders of flag leaf GS, grain GPT, protein accumulation, ratio of Glu/Gli were waterlogging+high temperature> waterlogging> high temperature and those of protein content and each protein ingredient content were waterlogging> waterlogging+high temperature> high temperature. The negative effects on flag leaf GS, grain GPT, protein accumulation of each stress in grain formation stage were higher than those of in milk-ripe stage, but there were no significant different on protein content and each protein ingredient content between two stages.(3) Spraying nitrogen compensated nitrogen nutrition, improved flag leaf GS, grain GPT, protein accumulation, protein accumulation, contents of protein, albumin, globulin and glutelin, had no significant effect on gliadin content, and led to improving ratio of Glu/Gli.(4) Correlation analysis indicated that correlation coefficients between activities of key regulatory enzymes involved in protein formation and grain yield, protein accumulation, ratio of Glu/Gli were significant, while correlation coefficient with protein content was not significant.4Effects of transient high temperature and waterlogging after anthesis on grain starch synthesis and accumulation of winter wheat and nitrogen management:(1) High temperature stress, waterlogging stress, high temperature+waterlogging double stress after anthesis all inhabited the sucrose, which is starch synthesis materials, supplying to grain, and inhibited the activities of starch synthesis enzymes which resulted in the decrease of grain starch accumulation. High temperature stress after anthesis increased slightly activities of SS、ADPGPPase、SSS、GBSS in winter wheat grain first and soon dropped significantly and waterlogging stress, high temperature+waterlogging double stress all decreased them continually. Compared with the reductions of grain ADPGPPase, SSS activities, high temperature decreased GBSS activities relatively slight, which resulted in increasing amylose content and decreasing amylopectin content, ratio of amylopectin and amylase. Waterlogging decreased grain starch accumulation, starch content, amylopectin content, and ratio of amylopectin and amylose, had no significant effect on amylose content.(2) There were significant interactions between high temperature and waterlogging. Adversity stress in grain formation reduced SS content, grain SS, ADPGPPase, SSS, GBSS activities, starch accumulation. There were no significant different on starch content and each starch ingredient content, ratio of amylopectin and amylase between two stages.(3) Spraying nitrogen improved SS content, grain SS, ADPGPPase, SSS, GBSS activities, starch accumulation, ratio of amylopectin and amylase, decreased content of amylose, and had no significant different on starch content and amylopectin content.5Effects of transient high temperature and waterlogging after anthesis on flour processing quality of winter wheat and nitrogen management:(1) High temperature increased flour wet gluten content, improved farinograph parameters, extensograph parameters, had no significant effects on pasting temperature, and had negative effect on other pasting parameters. Waterlogging reduced flour wet gluten content, had negative effect on farinograph parameters, extensograph parameters, had no significant effects on pasting temperature and increased other pasting parameters. Due to high temperature stress and waterlogging stress have a "hedge" effect in contents of starch and its composition, protein and its composition of wheat grain, high temperature+waterlogging double stress had an adverse effects on starch pasting parameters, but improved grain extensograph parameters, and had no significant effects on wet gluten content and farinograph parameters.(2) The negative effects on peak viscosity, hold trough, final viscosity, setback of each stress in grain formation stage were larger than those of in milk-ripe stage, but those of breakdown,pasting temperature,wet gluten content, farinograph parameters and extensograph parameters were not significant.(3) Spraying nitrogen improved wet gluten content, farinograph parameters, and esistance to extension, pasting parameters except pasting temperature and had no significant effects on pasting temperature, extension area, extensibility, and extension ratio.Spraying nitrogen improved grain yield and quality of winter wheat mainly through alleviating wheat plant senescence, improving the activities of enzymes related to synthesis of protein, starch and it was an effective way to alleviate negative effects of high temperature stress and waterloging stress. |
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