Nitrogen Vertical Distribution Differed in Foliar and Nonfoliar Organs of Dryland Wheat during Grain Filling

The role of N remobilization in nonfoliar and foliar organs influences the N vertical distribution and accumulation of N in grain. We hypothesized that the N concentrations in foliar and nonfoliar organs affect the remobilization, vertical distribution, and accumulation on N in grain. A 2-yr field experiment was conducted to evaluate the effects of N input and mulching practice on N remobilization and N vertical distribution in the canopy of winter wheat (Triticum aestivum L.). The results showed that foliar organs had higher N concentration than nonfoliar organs in all treatments. Among the nonfoliar organs, the flag leaf sheath had the highest N concentration, followed by glumes and rachillae combination, while the stem had the lowest N concentration at anthesis and maturity. In the different internode segments of the stem, N concentrations decreased with grain filling, except for the exposed part of the peduncle. There was a top-to-down decline in N concentration within the canopy. Foliar organs contributed the most N to grain followed by the stem and the glumes and rachillae combination. The N286 treatment significantly improved N accumulation, remobilization, and vertical distribution in the canopy and N content in grain. Nitrogen concentration in the grain was positively correlated with the difference in N concentrations between apical and basal vegetative modules.