| In wheat corn rotation area of northern China plain, regulations of the uptake, distribution and translocation of nitrogen in different organs of wheat at different growth stages were studied, and differences of nitrogen translocation conversion rate to grain of different vegetative organs of wheat were analysed. In field experiment with Xinong 979 as material, samples of wheat were obtained at different growth stages, such as tillering, wintering, regreening, jointing, heading, grainfilling and maturing stages. Then, different above ground organs, including leaf, leaf sheath, stem, spike, spike stalk, glume and grain, were separated, and their nitrogen contents were determined. At mature stage of wheat, the order of the nitrogen content in different organs of wheat was as grain > leaf > leaf sheath > glume > stem > spike stalk; and the order of the nitrogen accumulation in different organs of wheat was as grain > leaf sheath > leaf > stem > glume > spike stalk. The results suggested that grain was the biggest organ of nitrogen distribution and accumulation in wheat, and leaf was the biggest source organ of nitrogen. Additionally, the growth stage from jointing to heading of wheat was the biggest uptake stage of nitrogen. In wheat corn rotation area of northern China plain, nitrogen harvest index of grain was 68.48%; nitrogen translocation conversion rate to grain from leaf was 54.52%; the uptake rate of wheat from jointing to heading stage was 48.07% of that in all growth periods. So the basal/topdressing ratio of nitrogen fertilizer should be five to five. |
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