Characteristics Of Nitrogen Accumulation,Translocation And Utilization In Different Wheat Varieties

Nitrogen application plays an important role in plant growth and development.Wheat is one of the most important crops in the world.The study on nitrogen utilization efficiency of wheat and the analysis of genetic mechanism are of great significance to the breeding of wheat varieties and the improvement of wheat yield.The period after anthesis is important for wheat to obtain nitrogen,which promotes the formation of yield and quality.In this study,the six wheat experimental varieties in Huanghuai wheat region were used as a test material.The nitrogen transport and absorption after anthesis was studied.Physiological characteristics in seeding stage could reflect the condition of nirtogen supply.In this study,the soluble sugar content,NDVI value and chlorophyll content of 14 varieties with different nitrogen effects were measured at the seedling stage,and the correlation between them was studied.Root system architecture(RSA)determined the composition of plant root system,and significantly affected by nitrogen level.Under different nitrogen levels(deficiency and normal),120 winter wheat accessions from the Huanghuai wheat region were counted for their root architecture-related traits.Genome-wide association study(GWAS)was employed to identify the relevant loci for nitrogen use efficiency.1.Nitrogen accumulation and translocation after anthesis of different wheat varietiesAfter anthesis,nitrogen accumulation in vegetative organs of different wheat varieties showed a decreasing trend,while nitrogen accumulation in wheatear showed an increasing trend.The nitrogen distribution ratio of each organ was different in each wheat variety in each period.Among all wheat varieties,leaf and stem accounted for the largest proportion of nitrogen in anthesis period.At the maturity stage,most nitrogen is transferred to the grain,so the proportion of nitrogen in the grain is the highest,which is accounted for 63%?67.5%,significantly higher than that of all vegetative organs.The nitrogen distribution ratio of vegetative organ at the maturity stage was not of significant difference in rachis and glume,stem and leaf,but the lowest in leaf sheath.At the maturity stage,The proportion of nitrogen content in grain was not of significant difference in different varieties.The contribution rate of nitrogen transport to grains was highest in leaves.2.The Relationship between physiological characteristics at seeding stage and N-efficient typesFor 14 varieties derived from seeding stage of soluble sugar,chlorophyll content and the NDVI value,variance analysis results show that the soluble sugar content in the different between genotype and environment is extremely significant difference.There are significant differences between Chlorophyll content in different genotypes and N-efficient types;there are significant differences between NDVI value in different genotypes and N-efficient types,there are significant differences between extremely significant difference exists between the environment.And physiological character of different materials in the comparative analysis between different N-efficient types results show that NDVI value of the high-efficiency nitrogen types and the middle-efficiency nitrogen types is of significant difference,but with no significant difference between the low-nitrogen-efficient types.The difference between high-efficiency nitrogen types and middle-efficiency nitrogen types of chlorophyll content was not significant,and the middle-efficiency nitrogen types and low-efficiency nitrogen types of chlorophyll content was significantly;The differences between high-efficiency nitrogen types and middle-efficiency nitrogen types of soluble sugar content was significantly,but with no significant difference between the low-nitrogen-efficient types.3.Genome-wide association study of nitrogen related traits of wheat rootUnder different nitrogen levels(deficiency and normal),120 winter wheat accessions from the Huanghuai wheat region were counted for their root architecture-related traits(total root length,total root surface area,total root volume,average root diameter,and root tip number).Genome-wide association study(GWAS)was employed to identify the relevant loci for nitrogen use efficiency.A total of 53 associated loci were detected,which explained 7.2%–16.5% of the phenotypic variation.These loci distributed on all chromosomes and mainly centered on chromosomes 1A,1D,2A,2B,2D,3B,3D,4A,4B,5A,5B,5D,6B,7A and 7D,respectively.