| Climate warming is one of 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 response characteristics and their ecophysiological mechanisms on winter wheat growth and productivity,which have important theoretical and application prospects on wheat 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.The average temperature of canopy,central canopy,soil surface and soil 5 cm increased about 1.0 ℃ under nighttime warming before flowering.Accumulated temperature ≥0 ℃ of canopy and central canopy increased 87.9 ℃ and 45.8 ℃,respectively.Nighttime warming significantly 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.Besides,the heading date and maturity date were in advance.Nighttime warming shortened the vegetative growth stage,and extended the filling period.The total growth period was shortened.Nighttime warming and different nitrogen rates had combined effects on the growth and development of winter wheat,but the influences of different nitrogen rates on effective tiller,the highest stem tiller,flag leaf area per stem,leaf area per stem and leaf area index were larger than nighttime warming.However,the influences on plant height,sowing-heading days and heading-maturity days was converse.2.Nighttime warming significantly increased the effective ear number,grain number per panicle,1000-grain weight,and the aboveground biomass and harvest index.And then the practical yield and theoretical yield were improved;The practical yield for N150,N225 and N375 respectively increased by 29.7%,35.3%and 29.7%,and theoretical yield respectively increased by 27.6%,37.6%and 13.9%.The 225 kg-ha-1 nitrogen rates could get maximum practical and theoretical yield as well as the highest harvest index.There are two factors of nighttime warming and different nitrogen rates that contribute to the practical and theoretical yield.Nitrogen rates play a greater influence on the effective ear number and harvest index than nighttime warming.Nighttime warming plays a greater influence on the grain number per panicle,1000-grain weight and the aboveground biomass.Eventually nighttime warming plays a greater influence on practical yield and theoretical yield.3.The main reasons why we could get the higher yield of winter wheat under nighttime warming are as follows.Nighttime warming treatment significantly improved the effective ear number,grain number per panicle,1000-grain weight,the aboveground biomass and harvest index.The main physiological performances are as follows:SPAD values were significantly improved,which delayed plant senescence at the jointing,heading and flowering stages.SPAD values were proportional to the net photosynthetic rate.While SPAD values increased,the net photosynthetic rate of flag leaves was also improved.The SS(sucrose synthase)and SPS(sucrose phosphate synthase)activities were significantly improved in the winter wheat flag leaves.The leaves’ soluble total sugar content and sucrose content were increased.Then the aboveground biomass was improved which was contributing to increasing grain yield.The GS(glutamine synthetase)and NR(nitrate reductase)activities were significantly improved.The free amino acid content and total nitrogen content in wheat leaves,stems and grains was significantly improved which were contributing to increasing soluble protein. |
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