Response Of Nitrogen Accumulation,transportation And Metabolism To Nitrogen Application Rate In Wheat Cultivars With Different Grain Protein Content

In order to clarify the differences of nitrogen absorption and utilization,yield and quality formation of wheat cultivars with different grain protein content and their responses to nitrogen fertilizer,and to form a nitrogen fertilizer application technology with high yield and good quality,field experiments were carried out in the wheat experimental base in Wenxi from 2018 to 2020.In 2018-2019,a single factor completely random design was adopted: LX99,HM13,SN22,LX77,YN999 and SN29.Two factor split plot design was used in the experiment from 2019 to 2020.The main plot was medium protein cultivars SN22 and high protein cultivars YN999 and JM44,and the sub plot was 75（N75）,150（N150）and 225 kg hm^-2（N225）nitrogen application rates.The effects of nitrogen fertilizer on nitrogen accumulation,translocation,yield and quality with different experimental treatment were studied,and the physiological mechanism was analyzed.Cluster analysis results from 2018 to 2019 showed that YN999,HM13 and LX99 were high protein content cultivars,SN22,SN29 and LX77 were low protein content cultivars.Compared with the low protein content cultivars,the high protein content cultivars increased the nitrogen absorption and translocation capacity,increased the panicle number,and decreased the grain number per panicle,1000 grain weight,yield and water use efficiency.They improved the water absorption rate,dough formation time,dough stability time,weakening degree and farinogram quality.They also increased the nitrogen absorption efficiency by 4.1% and partial nitrogen productivity by 1.8%.From 2019 to 2020,the results showed that SN22,YN999 and JM44 increased the activities of glutamine synthetase（GS）and glutamic acid synthetase（GOGAT）and soluble protein content in flag leaves and grains after anthesis,increased the nitrogen accumulation of plants at maturity stage,nitrogen accumulation after anthesis and its contribution rate to grains,and improved the yield,grain protein,and protein yield.And their nitrogen uptake efficiency,nitrogen harvest index and nitrogen partial productivity were improved.The grain protein content,flour water absorption,stabilization time,wet gluten content and falling value of low protein content cultivars SN22 increased,but there was no significant difference between 150 kg hm^-2 and 225 kg·hm^-2 N application rates.The grain protein content and processing quality of YN999 and JM44 were the highest under 225 kg·hm^-2 nitrogen application.With the increase of nitrogen application rate,panicle number,1000 grain weight,yield and partial nitrogen productivity of YN999 and JM44 increased,but nitrogen absorption efficiency decreased.In conclusion,YN999 and JM44 increased the activities of nitrogen metabolism enzymes in flag leaves and grains after anthesis,and increased the nitrogen accumulation of plants at the late growth stage.The combination of 225 kg·hm^-2 nitrogen fertilizer could achieve the simultaneous improvement of yield and quality.SN22 combined with 150 kg·hm^-2 nitrogen fertilizer had the better effect.