Differences In Yield And Quality Of Wheat With Different Gluten And Their Responses To Nitrogen Fertilizer And Density

The middle and lower reaches of the Yangtze River is the second largest wheat production area in China,of which rice wheat rotation is the main planting mode and one of the rice wheat rotation modes.The wheat planting area in this area is large,but due to the yield constraints caused by complex climate and soil factors,the yield potential in this area is difficult to play out.The low yield level and grain quality of wheat in this region have seriously restricted the development of wheat industry in this region.Therefore,it is necessary to carry out cultivation experiments of density and nitrogen management for varieties with strong adaptability in this region,to explore the physiological mechanism of yield and quality differences between different quality types of wheat under the regional climate and planting mode,and to reveal the key physiological processes and solutions that restrict the improvement of wheat yield and quality.It is very important for seeking the target strategy of achieving both yield and quality in this climate region to further improve the wheat yield level in the middle and lower reaches of the Yangtze River and promote industrial development.This study is carried out in Xiangyang City,Hubei Province,in the rice wheat rotation system in the middle and lower reaches of the Yangtze River Plain.The test materials are strong gluten wheat Zhengmai 9023（ZM9023）,medium gluten wheat Emai 596（EM596）and weak gluten wheat Shengxuan 6（SX6）,which are widely promoted wheat varieties of different quality types.By setting different planting densities of 200plants m^-2（D1）and 400 plants m^-2（D2）,And with three different nitrogen topdressing treatments(total nitrogen 225 kg ha^-1),50%base fertilizer+50%rejuvenation fertilizer（S1）,50%base fertilizer+50%jointing fertilizer（S2）and 50%base fertilizer+20%rejuvenation fertilizer+30%jointing fertilizer（S3）,to study the differences in yield and nitrogen use efficiency of wheat varieties of different quality types and their response to nitrogen topdressing nitrogen fertilizer period and density,It is expected to provide theoretical basis and technical support for further improving the yield and quality of wheat and nitrogen use efficiency in this region.The main results of this study are as follows:（1）With the increase of density,the number of ears of each wheat variety increased,the number of ears per unit area under D2 density was 130%-140%of D1,and the number of grains per ear and 1000 grain weight decreased.The yield of ZM9023 and SX6 increased with the increase of density.With the backward shift of topdressing period,the yield of different treatments showed a downward trend or no increase,while the topdressing treatment of rejuvenation+jointing period increased the yield.The maturity of EM596 and the accumulation of dry matter after anthesis decreased with the increase of density,while ZM9023 showed the opposite.The highest yield varieties in the two years were SX6 and EM596,and the yields reached 6486 kg ha^-1 and 7501 kg ha^-1 respectively.EM596 has the highest filling rate,the SPAD value of flag leaf at the late filling stage is higher than that of other varieties,and the filling duration is long,so the 1000 grain weight is significantly higher than that of the other two varieties.（2）Under the condition of low density,the yield of the three wheat varieties under S1and S3 treatment was higher than that under S2 treatment,between 5204-6080 kg ha^-1,but under the condition of high density,it was the highest under S3 treatment,in which SX6and ZM9023 reached a significant level.The number of grains per ear under S3 treatment was the highest,and the difference between treatments was significant.The yield of the three varieties was the highest under D2S3 treatment,but there was no significant difference between EM596 and D2S3 under D1S1.The yield of SX6 was slightly lower under D1S1,while ZM9023 was significantly lower than D2S3 under D1S1.（3）With the increase of planting density,the starch content of wheat grains of the three varieties increased,with strong gluten wheat the highest and weak gluten wheat the lowest;Except for EM596,the grain protein content of SX6 and ZM9023 also increased with the increase of planting density.When the topdressing period moved from the turning green stage to the jointing stage,the starch content of wheat grains decreased,but the total protein content increased.The response of grain protein content of different varieties of wheat to topdressing period is different.The grain protein content of EM596 is the lowest when topdressing treatment is carried out at S3 rejuvenation+jointing stage.The response of different varieties of wheat to it is different.The protein content of weak gluten wheat is the lowest.The grain protein content of strong gluten ZM9023 and SX6 and weak gluten wheat is the highest in S2,and the lowest in S1,which is between rejuvenation topdressing treatment and jointing topdressing treatment.（4）With the increase of density,the nitrogen accumulation,nitrogen use efficiency（NUtE）and nitrogen harvest index（NHI）of ZM9023 and SX6 decreased during flowering and maturity,and the activities of nitrate reductase（NR）and ammonia amide synthetase（GS）decreased with the increase of density,while the activities of glutamine synthetase（GS）were higher at low density.The response of NUtE to density is different among varieties.The NUtE of ZM9023 is higher at low density,which is opposite to that of EM596,and SX6 is basically the same at two densities.The response of NUtE to topdressing period was also different among varieties.ZM9023 was the highest under S1 and S3 treatment,EM596 was the highest under S3 treatment,and SX6 was the highest under S1 treatment.However,the NR and GS activities of flag leaves at flowering stage were consistent.NHI of the three varieties was the highest under S2 treatment.As the topdressing period moved back,the nitrogen accumulation after anthesis of wheat showed an upward trend,and the activities of NR and GS in flag leaves showed an upward trend.In conclusion,the increase of density has a better effect on the yield and quality of the three gluten wheat varieties in this experiment under high density,but different varieties have different responses to density and topdressing period in terms of quality and nitrogen use efficiency.Therefore,for different gluten wheat varieties,we should formulate appropriate cultivation measures,reasonably arrange the sowing density and topdressing period,optimize and improve the quality of wheat population,and finally achieve the synergy of yield,quality and efficiency,and improve the efficient utilization of fertilizer.