Abstract: 【Objective】Nitrogen plays important roles in promoting plant growth and development. The objective of this study is to clarify the characteristics of distribution and transportation for barley nitrogen efficiency genotype, and to provide a theoretical basis for efficient nitrogen management and high-yield cultivation of good varieties.【Method】In this study, a soil culture pot experiment was conducted with barley genotype of high nitrogen utilization efficiency (DH61, DH121+) and low nitrogen utilization efficiency (DH80). Four nitrogen treatments were designed, including no nitrogen, low nitrogen (125 mgN·kg^-1 soil), normal nitrogen (250 mgN·kg^-1 soil) and high nitrogen (375 mgN·kg^-1 soil), respectively. The purpose was analysis grain yield, aboveground biomass , the characteristics of nitrogen transportation and fractions in different organs of barley with high nitrogen utilization efficiency (NUE) at late growth stage.【Result】When applied nitrogen reduced, the amount of aboveground biomass and grain yield were decreased among all tested cultivars. Under the same nitrogen application level, the amounts of biomass and grain yield of high NUE genotype were higher than that of low NUE genotype. The grain yield of high NUE genotype was, respectively, 1.96 times and 2.03 times, 2.10 times and 2.37 times higher than that of low NUE genotype in no nitrogen and low nitrogen treatments. Nitrogen concentration of high and low NUE genotype had no significant difference in no nitrogen and low nitrogen treatments at flowering and grain filling stages. High NUE genotype had a strong ability in dry matter forming. The amount of nitrogen accumulation of high NUE genotype was higher than that of low NUE genotype. And the ratio of nitrogen accumulation during the whole growth period of high NUE genotype was higher than that of low NUE genotype before flowering stage. Nitrogen accumulation of high NUE genotype was 1.48 times, 1.36 times and 1.37 times higher than that of low NUE in low nitrogen (125 mgN·kg^-1 soil), normal nitrogen (250 mgN·kg^-1 soil), and high nitrogen (375 mgN·kg^-1 soil) treatments. Adequate nitrogen accumulation of high NUE before flowering had laid a foundation for early filling of seeds. When applied nitrogen reduced, nitrogen translocation showed a single peak curve, nitrogen transfer rate and the amount of nitrogen transported to grain contribution rate gradually declined, over fertilization of nitrogen fertilizer is not conducive to grain transport. For high NUE genotype(DH61,DH121+), nitrogen in grain mainly relied on nitrogen translocation from vegetative organs, which accounted for 35.06%, 40.06% and 76.37%, 81.72% in no nitrogen and low nitrogen treatments, respectively; but for low NUE genotype(DH80), nitrogen in grain mainly relied on nitrogen uptake by root at reproductive stage which accounted for 68.20% and 34.84%. Higher transfer efficiency associated with different forms of nitrogen in plant composition and change. In different nitrogen treatments, assimilable nitrogen content in stalk and leaf increased, functional nitrogen content changes smoothly and structural nitrogen content was reduced from flowering to filling, while assimilable nitrogen content increased, and structural nitrogen content slowly declined in grain. High NUE showed a strong decline and nitrogen transport capacity of the structural nitrogen content. The structural nitrogen content of high NUE in stem and leaf decreased by 49.65% and 62.54% in low nitrogen treatment from flowering to filling, and it decreased by 66.54% and 28.17% from heading to maturity.【Conclusion】Grain nitrogen content of high NUE in stems and leaves is decided by the structural nitrogen content decomposition and transformation after flowering, and structural nitrogen recycling in vegetative organs conducive to nitrogen use efficiency.

Key words: barley, high nitrogen utilization efficiency genotype, nitrogen transportation, fractions