| Nitrogen application at different growth stages of potato will have effect on tuber yield and quality by influencing the vine growth and tuber development. Using Kexinl3as experimental materials. Plot experiments were conducted to study the effects of tuber yield and quality as well as accumulation, translocation and distribution of dry matter, N, P and K. The research to indicate the best method of N fertilizer application for providing the basis for improve yield and quality of potatoes. This experiment under the condition of N180kg/hm2, setted up six treaments.3:2,1:1A,1:2A applied by ratios of3:2,1:1,1:2at the early tuber formation stage.1:1B,1:2B applied by ratios of1:1,1:2at the end of tuber formation stage.1:1:1applied by ratios of1:1:1at the early tuber formation stage and. the early tuber bulking stage. The main conclusions were as follows:N content were showing the order leaves> petioles> stems> tuber all the time. The N content of tuber (1:1B) increased by16%than1:1:1, the N accumulation of tuber were increased also by24%than3:2and1:1:1, and the N distribution ratio of tubers were increased by16%and29%than3:2and1:1:1at harvest. Each index all reached5%significant level.P content were showing the order stems> leaves,petioles> tuber before the end of tuber bulking stage, but that were tuber> leaves,petioles> stems after the end of tuber bulking stage. Applying the1/2N at the end of tuber formation stage can promote the accumulation and distribution of P in the tubers.1:1B accumulated more P than3:2and1:1:1by18.8%and38.8%, and was higher distribution ratio by9.4%and20.6%at harvest. Each index all reached5%significant level.K content were showing the order petioles> stems> leaves> tuber before the end of tuber bulking stage, but that were tuber> stems> petioles> leaves after starch accumulation stage.. The K content of tuber was less than vegetative organs before the tuber bulking stage, and was on the contrary after starch accumulation stage.3:2and1:2ratio of nitrogen basal and topdressing was selected will promote that K uptake by potato plant, but chosen1:1ratio of nitrogen basal and topdressing can improve the distribution of K in the tubers. The K accumulation of potato plant and tuber (1:1) was always lower, but the distribution of K in the tubers were increased by13.5%and11%than3:2and1:2at harvest (p<0.05)Dry matter accumulation of potato whole plant was "slowâ†'fastâ†'slowâ†'fastâ†'slower" shaped.The that of1:1A and1:2A vegetative organs showed a single peak curve, and that of3:2and1:1:1and1:1B and1:2B showed a bimodal curve.When tuber formed and the that of tubers was always a linear growth. At harvest period, the dry matter accumulation of potato (1:1B) was highest,and that of tuber were increased by13%and16%than3:2and1:1:1, and the distribution of dry matter in the tubers were increased by13%and12%(p<0.05). The later N topdressing the higher dry matter accumulation of tuber will obtain with1:1ratio of nitrogen basal and topdressing. Dry matter accumulation of potato whole plant of what applying1/3N at the early of tuber bulking stage was highest, but the distribution of dry matter in vegetative organs was larger, and dry matter accumulation of tuber was lowest.1:1B obtained the highest yield (38.1t/hm2), compared with1:1:1, tuber yield increased by14.1%, harvest index increased by16.7%; Compared with1:2A, marketable tuber ratio increased by4.4%(p<0.05). Dressing N at the early tuber bulking stage (1:1:1) or applying2/3N at the end of tuber formation stage (1:2B) could decrease the dry matter content of tuber (p<0.05), but could decrease specific gravity slightly. The suitable N fertilizer application ratio of basal and topdressing could influence the yield and quality of tuber largely. |
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