Studies On N Uptake And Distribution Characteristics And Physiological Mechanism For High Efficient Utilization In Potato

Nitrogen is one of the essential nutrient for plant growth. Nitrogen uptake, assimilation and translocationhave important influence on growth and development and yield formation directly or indirectly. In this paper,the method of field plot, micro-plot experiment and laboratory analysis are applied to study the influencemechanism of nitrogen nutrition conditions on potato tuber development, formation of yield and quality, andthe dynamic change regularity of different plant nitrogen forms, and to reveal relationship between N-contentin potato plants in whole growth period and yield; At the same time to study¹⁵N accumulation, uptakepercentage, distribution, nitrogen use efficiency in potato and nitrogen distribution in soil using¹⁵N tracingtechnique. The main results obtained from this experiment are as follows:1,The dry matter accumulation was increased in different Potato growth periods through nitrogenfertilizer application. The plant dry matter accumulation of nitrogen treatments was8725.8～11707.1kg·hm^-2at105days after sowing, and was increased from50.37%to71.38%compared with N0. With the increase ofnitrogen amount, the whole plant dry matter accumulation also increased gradually. Compared with N0, potatotuber dry matter accumulation was increased from42.80%to91.59%by nitrogen treatments at harvest, andnitrogen120kg·hm^-2treatment was highest.2,Nitrogen fertilizer application increased the yield of potato on the basis of phosphorus and potassiumfertilizer, and yield was increased from22.30%to61.48%. Nitrogen120kg·hm^-2treatment has the largestincrease in yield, and the yield was significantly higher than0and60kg·hm^-2treatments. Nitrogen fertilizerapplication increased significantly the proportion of potato middle tuber. With the increase of nitrogen amount,the large tuber weigh also increased gradually. Compared with other treatments, the large tuber weigh wasincreased from4876.8kg·hm^-2to1265.0kg·hm^-2by nitrogen120kg·hm^-2treatment.3,With the increase of nitrogen amount, protein content of tuber also increased gradually from63to91days after sowing, and nitrogen120kg·hm^-2treatment decreased rapidly after that. The vitamin C content ofpotato tubers with growth progress increased first and then decreased. When excessive nitrogen fertilizer atpotato tuber development later stage, vitamin C content of tuber decreased. The tuber educing sugar content ofnitrogen120kg·hm^-2treatment in the tuber growth period was the highest, and the soluble sugar contentdecreased gradually. Excessive nitrogenous fertilizer was not conducive to the transformation of soluble sugarto starch. The potato tuber starch content respectively was61.92～66.91g·100g^-1.DW at harvest. Excessivenitrogenous fertilizer was not conducive to the tuber starch accumulation and the amylose relative contentincrease at potato growth later stage. The tuber phenols content decreased first and then increased in potatotuber development period. Nitrogen application could obviously promote the Phenolics Metabolism andtransformation, decreased the tuber phenols content at potato tuber development later stage and improved thequality of tuber.4,Nitrogen application increased AN content of leaf. Tuber AN content of nitrogen treatment in the tuberdevelopment period was higher than one of N0. With the increase of nitrogen amount, SN content of stem alsoincreased gradually. Synthesis of SN determined the direction of the flow of nitrogen, was the main factors thatpromote nitrogen flow between potato organs, and was the "power source" through which potato tuber absorbed nitrogen efficiently.5,There is a very significant regression relationship between stem nitrogen content at each potato growthstage and yield, and stem nitrogen nutrition levels were important nutritional factors that could influencepotato yield. It was very important for potato to get higher yield that stem maintained higher nitrogen content.The leaf nitrogen content had important effects on yield at tuber formation stage; however one of stem wasmore apparent. There is a very significant regression relationship between root nitrogen content at starchaccumulation stage and yield, but one of stem was more apparent too.6,The absorbed nitrogen in above-ground of potato from fertilizer accounted for17.48%～29.31%of thetotal nitrogen, and that in tuber was17.25%～20.57%, and root was19.72%～24.82%, and whole plant was17.41%～28.98%. The absorbed nitrogen in potato plant was mainly from soil. The nitrogen uptake ofabove-ground from fertilizer was0.174～0.327g·plant^-1, and that of tuber was0.022～0.357g·plant^-1, and rootwas0.011～0.022g·plant^-1, and whole plant was0.185～0.578g·plant^-1. The nitrogen use efficiency of¹⁵Nfertilizer was10.28%～32.11%for potato. The range of variation of soil ANvalue was18.97～36.73kg·hm^-2inthe process of growth and development of potato. Soil ANvalue reduced12.93kg·hm^-2from49to77daysafter sowing, and the decline was by35.22%ï¼›It increased3.84kg·hm^-2from77to91days after sowing, andthe improvement was by16.13%.7,The nitrogen use efficiency of manure was2.16%～31.62%in the whole growth period of potato, andthat of chemical fertilizer was8.85%～19.42%. With the combined application of organic and chemicalfertilizers, the nitrogen from chemical fertilizer was the important N source for potato. However, manure had alarger role in late growth stage of potato.