Response Of Grain Yield And Quality Of Wheat Recombinant Inbred Lines To Nitrogen Reduction

Recombinant inbred line populations have similar genetic backgrounds and are permanent populations.They can be repeated comparative tests and are suitable for the study of complex traits that are greatly affected by the environment.In this experiment,the population of Ning 7840 and Clark wheat recombinant inbred lines and their parents were used as materials.Two nitrogen fertilizer levels of nitrogen reduction and control were set at 150 and 240 kg·ha-1,respectively.Differences in quality,dry matter accumulation,and nitrogen transport response to nitrogen reduction,and further layered milling techniques were used to explore the spatial distribution of the response of protein content in different parts of wheat grain endosperm to nitrogen fertilizer.The main findings are as follows:1.The effect of nitrogen reduction on the wheat yield of recombinant inbred linesThe amount of nitrogen fertilizer significantly affected the spike number,spike number,grain weight,yield,harvest index and biological yield of the recombinant inbred line population.There were differences in the response of different wheat lines to nitrogen fertilizer among the recombinant inbred line groups.With reduced application of nitrogen fertilizer,the number of panicles,number of spikes per ear,harvest index and biological yield decreased significantly with the decrease of nitrogen fertilizer application,while the weight of 1000-grain showed a clear upward trend with the decrease of nitrogen fertilizer application.The change trend of flag leaf SPAD value is relatively stable.As the fertility process advances,the SPAD value gradually decreases.Nitrogen reduction treatment had different effects on SPAD values at different growth stages.From the perspective of change rate,jointing stage>heading stage>flowering stage>filling stage.Based on the clustering analysis of the yield and nitrogen responsiveness of the tested genotypes under reduced nitrogen and control conditions,the recombinant inbred line population can be divided into yield-sensitive nitrogen-responsive sensitive type,yield-sensitive nitrogenresponsive type,and yield dullness There are four types of nitrogen-responsive sensitive type and sluggish yield.The two-year results show that there are 8 yield-sensitive nitrogen-responsive strains,12 yield-sensitive nitrogen-responsive strains,17 yieldsensitive nitrogen-responsive strains,and 10 yield-sensitive nitrogen-responsive strains.2.The effect of nitrogen reduction on the wheat quality of recombinant inbred linesThe grain protein content,protein yield,wet gluten content,and hardness index of the wheat recombinant inbred line population decreased within a certain range with the decrease of nitrogen application.The quality traits of different wheat lines differed significantly due to different genotypes.According to the distribution range of hardness parameters,we divide them according to different endosperm texture,which can be divided into soft wheat,hard wheat and mixed wheat.Among them,58 are soft wheat,16 are mixed wheat,and59 are hard wheat.The stratification results show that from the outer layer to the inner layer of mature grains,the protein content increases first and then decreases,with the highest content in the P2 and P3 layers（transition layer and outer endosperm）,and the protein content in the endosperm decreases gradually from the outer layer to the inner layer.Nitrogen reduction reduces the protein content of each layer of the grain.The rate of change of protein content in each layer can be used to reflect its sensitivity to nitrogen fertilizer response,so that it can be divided into three types:inner layer response sensitive type,middle layer response sensitive type and outer layer response sensitive type.Among them,there are 34 inner layer response sensitive lines,49 middle layer response sensitive lines,and 50 outer layer response sensitive lines.3.The effect of nitrogen reduction on the characteristics of nitrogen absorption and utilization of wheat in recombinant inbred linesThe amount of nitrogen fertilizer used is reduced,and the amount of material transported before flowering,the amount of dry matter accumulated after flowering,the nitrogen content of plants and grains,and the amount of nitrogen accumulated are also reduced.Compared with normal nitrogen application,nitrogen reduction treatment significantly reduced the transfer of dry matter from wheat vegetative organs stored before flowering to grains.Nitrogen fertilizer absorption efficiency,nitrogen fertilizer agronomic efficiency,nitrogen fertilizer physiological efficiency,and nitrogen harvest index increased with decreasing nitrogen application.There are also significant genotype differences in nitrogen dry matter production efficiency and nitrogen grain production efficiency.With reduced nitrogen fertilizer application,plant nitrogen content,grain nitrogen content,grain nitrogen accumulation,plant nitrogen accumulation during flowering,plant nitrogen accumulation during maturity,post-flowering nitrogen accumulation,and postflowering accumulated nitrogen contribution rate all decreased.Due to the influence of its own genetic factors,different wheat lines have different nitrogen absorption capacity,and thus different nitrogen content.The variation range under nitrogen reduction treatment is larger than that of the control,which shows that as the nitrogen fertilizer application amount increases,the coefficient of variation between lines gradually decreases,and the difference gradually decreases.According to the six indicators selected by path analysis,the number of ears,protein yield,wet gluten content,NUTE（nitrogen utilization efficiency）,NAE（nitrogen fertilizer agronomy utilization rate）,NPEG（nitrogen grain production efficiency）,the six indicators were used to reconstitute self-rebred The sensitivity of the nitrogen fertilizer response of the line group is divided.Using the principal component analysis method,cluster analysis is carried out according to the comprehensive score,and finally it can be divided into three types:nitrogen retardation type,nitrogen intermediate type and nitrogen sensitive type.Among them,21 were nitrogen-deficient,6 were nitrogen-neutral,and 74 were nitrogen-sensitive.This experiment explored the effects of nitrogen reduction on the yield,quality,dry matter accumulation and nitrogen transport of recombinant inbred lines.And using layered milling technology,the mature grains are layered from the outside to the inside according to the ratio of 7%[P1],23%[P2],20%[P3],30%[P4],20%[P5]Powder to explore the spatial distribution of nitrogen response in different parts of wheat grain endosperm.Based on the clustering analysis of the yield and nitrogen responsiveness of the tested genotypes under nitrogen reduction and control conditions,the recombinant inbred line population can be divided into yield-sensitive nitrogen-responsive sensitive type,yield-sensitive nitrogen-responsive type,and yield dullness There are four types of nitrogen-responsive sensitive type and sluggish yield.The two-year results showed that there were 8 yield-sensitive nitrogen-responsive types,12 yield-sensitive nitrogenresponsive lines,17 yield-sensitive nitrogen-responsive lines,and 10 yield-sensitive nitrogen-responsive lines;Divided by the rate of change of laminin content,34 inner-layer response-sensitive lines,49 middle-layer response-sensitive lines,and 50 outer-layer response-sensitive lines can be screened out;the number of spikes and proteins screened by path analysis Yield,wet gluten content,NUTE（Nitrogen Utilization Efficiency）,NAE（Nitrogen Fertilizer Agronomy Utilization Rate）,NPEG（Nitrogen Grain Production Efficiency）are the six indicators for the absorption,utilization,accumulation and translocation of nitrogen in the recombinant inbred line population.The sensitivity of nitrogen fertilizer response to yield and quality components is generally divided.Using principal component analysis and cluster analysis based on comprehensive scores,it can be divided into nitrogen-blunt type,nitrogen intermediate type and nitrogen sensitive type.Among them,21 were nitrogen-deficient,6 were nitrogen-neutral,and 74 were nitrogen-sensitive.At the same time,it also provides excellent germplasm resources for genetic breeding,and provides a certain reference basis for the determination of new breeding goals.