Characteristics Of Nitrogen Utilization Under Different Nitrogen Strategies And Nitrogen Diagnosis In Potato

In this study, potato was evaluated to investigate the effect of yield formation and qualitative under different applying nitrogen rates, and the uptakes, accumulations and allocation of nitrogen, and NUE, efficiency analysis, and indexes and model of nitrogen diagnosis were established. The main results were shown as followings:The per shoot tuber yield, average tuber yield and yield increased with the increase of nitrogen rate when the nitrogen rate was less than 210kg·hm^-2, they were decreased by higher nitrogen application. The soluble protein content and deoxysugar content with the increase of nitrogen rate, but the starch protein content decreased.With square regressive curve, the optimal nitrogen application was200.5kg·hm^-2.Nitrogenous fertilizer increased the biomass, the leaf area, and the photosynthesis characteristic of potato. The best survey time of potato was AM 9: 00 11: 00 due to great change of photosynthesis parameter in else time.The absorption and accumulates of nitrogen decreased after increased with time in the period. Maximal value of the absorption and accumulates accordingly emerged in tuber initiation stage and in tuber bulking stage.The absorption and accumulates of nitrogen and the different organs nitrogen content increased with the increase of nitrogen rate, and this tendency was not obviously in seedling stage. Production value increased with the increase of nitrogen rate when the nitrogen was less than 210kg·hm^-2 , they were decreased by higher nitrogen application; But nitrogenous fertilizers efficiency increased with the increase of nitrogen rate when the nitrogen was less than 135kg·hm^-2 , they were decreased by higher nitrogen application. Agronomic efficiency (AE) and Physiological efficiency (PE) increased with the increase of nitrogen rate when the nitrogen was less than 135kg·hm^-2, they were decreased by higher nitrogen application. Recovery efficiency (RE) and Partial factor productivity of applied N (PEP) decreased with the increase of nitrogen rate.The results showed significant correlations between SPAD readings and chlorophyll content, chlorophyll content of leaf can be reflected by SPAD readings. The forth leaf (form the top of shoot) was suitable for nitrogen nutritional status test. The forth leaf (form the top of shoot) could be signal leaf of potato nitrogen nutritional status, and results showed significant correlations between SPAD readings of The forth leaf (form the top of shoot) and N applying rate, soil Nmin, petiole nitrate...