Response Characteristics On Different Nitrogen Rates Under Night Warming Of Grain Yield And Quality Of Winter Wheat

Climate warming and nitrogen deposition have been the main characteristics of global climate change.Warming mainly occurred in winter and spring.And warming amplitude is higher at nighttime than during the day.Nitrogen is necessary to the growth of wheat as a large amount of nutrients.Nitrogen and temperature have joint functions of the growth and yield of winter wheat.In order to investigate the effects of different nitrogen rates on grain yield and quality under nighttime warming of winter wheat,which have important theoretical and application prospects on wheat high-yield cultivation under climate warming,this study set the double factors of open nighttime warming(NT means nighttime warming treatment;CK means control treatment.The same is as below)and different nitrogen rates(N150,N225 and N375 mean 150,225,375 kg ha-1 for nitrogen,respectively.The same is as below)field experiment.Yangmai 13 was the materials.Conclusions are as follows:1.Nighttime warming before flowering changed the microclimate environment of the wheat field.The average temperature of canopy,central canopy,soil surface and soil 5 cm increased by 1.1 ℃,0.7℃,1.9 ℃ and 1.1 ℃,respectively.Accumulated temperature ≧ 0 ℃of canopy,central canopy,soil surface and soil 5 cm increased by 57.61 ℃,38.32 ℃,66.84℃ and 37.21 ℃,respectively.The soil water content decreased by 4.7%compared with the control at nighttime warming treatment.2.Nighttime warming before flowering and different nitrogen rates changed the growth period,morphological indexes and yield components of winter wheat significantly.Nighttime warming treatment shortened the initial heading stage,extended the filling period.The total growth period was shortened.Nighttime warming treatment increased the numbers of maximum tiller,effective tiller and plant height,and improved the flag leaf area per stem,leaf area per stem and leaf area index at the flowering stage.There are two factors of nighttime warming and different nitrogen rates that contribute to the morphological indexes of winter wheat and nitrogen rates was the main influencing factor.Nighttime warming treatment significantly increased the effective ear number,grain number per panicle,which eventually improved the practical yield and when the nitrogen rate at the 375 kg·ha-1 the yield reached the maximum.Then nighttime warming treatment played a greater influence on the yield and growing process of winter wheat.Nighttime warming treatment improved the aboveground biomass and harvest index and when the nitrogen rate at the 375 kg·ha-1 the harvest index reached the maximum which mean that application of high N would be benefit to the harvest index under nighttime warming treatment.Nighttime warming before flowering and different nitrogen rates had some influence on the nitrogen uptake and utilization of winter whcat.The nitrogen use efficiency was the highest when the nitrogen rate was 375 kg·ha-1 under the ninghttime warming.3.Nighttime warming before flowering and different nitrogen rates made some effects on the process of photosynthetic physiological of winter wheat which played a good role in improving the SPAD values and the net photosynthetic rate.When the nitrogen rate at the 375 kg ha-1 the SPAD values and the net photosynthetic rate reached the maximum.The content of chlorophyll increased,which promoted the photosynthesis of plants,and promoted the synthesis and accumulation of photosynthetic products.In this experiment nighttime warming treatment improved the pre-anthesis translocation amount,post-anthesis accumulation amount and the contribution of pre-anthesis translocation to grains.And as the increase of the nitrogen rates the pre-anthesis translocation amount,post-anthesis accumulation amount showed an increasing trend under the nighttime warming,among them,the temperature was the main factor.4.Nighttime warming before flowering improved the protein and protein fraction content of winter wheat and it reached the maximum under nighttime warming the application of high N(375 kg ha-1).Nighttime warming treatment did not have a significant effect on the starch and its components of winter wheat,but the different nitrogen rates reduced the starch and amylopectin significantly.Under the nighttime warming treatment,the AM/AP(Amylose/Amylopectin)reached the maximum when the nitrogen rate at the 375 kg ha-1.Then nitrogen rate treatment played a greater influence on the protein and protein fraction content and the starch and its components of winter wheat.Nighttime warming before flowering improved the key enzyme(NR,GS,SS,SPS)activities in carbon-nitrogen metabolism of the flag leave and grain of winter wheat.Under the nighttime warming,the key enzyme(NR,GS,SS,SPS)activities in carbon-nitrogen metabolism showed an increasing trend along with the increases of nitrogen,and the nitrogen rate was the main factor.This result indicated that application of high N under nighttime warming treatment would be benefit to the carbon-nitrogen metabolism and would improve the yield and protein of winter wheat.