The Effect Of Different NPK Fertilizer Combination On The Yield And Quality Of Potato

China is the biggest country of potato production in the world. But the average yield unit area is lower than other countries and the quality of tuber is also bad. One of the most important reasons is that fertilization is unreasonable. The trial was conducted to investigate the effects of yield and quality of tuber by fertilizing different concentration of NPK. Based on the data of experiment, the cultural mathematical model were set up by computer such as agricultural characteristics, chlorophyll content, photosynthetic rate, yield, dry matter content, starch content, vitamin C content, protein content and so on. The following conclusion were obtained:(1) Nitrogen was the important factor to plant height in the experiment, potassium was second. It was not disadvantageous to grow for plant, if nitrogen and potassium were fertilized excessively. The main factor was nitrogen to stem diameter, followed by potassium. But phosphorus had no significant influence on the main stem diameter. In trial, N P K were not significantly correlated to number of branch and the distance of burl.(2) In trial, it was high significantly correlated to chlorophyll content as to nitrogen and potassium. But phosphorus and the interaction of three factors had no significant influence on chlorophyll content. The size of order which three factors affected the rate of photosynthesis was K>P>N, but only potassium was significant to photosynthetic rate. Therefore, the main factors were potassium in photosynthesis. Considering the parameters of photosynthesis, it is advantageous to the growth and morphogenesis of plant that appropriate nitrogen is fertilized during the prophase of growth. And it can accelerate the form of tuber and the accumulation of starch.(3) Potassium was the most importance on the yield of potato among three factors. The second was nitrogen. Although phosphorus had a certain impact, the result was not significant. The growth of aboveground plant was correlated significantly to yield with a correlation coefficient of 0.627. In the same way, potassium was most important to the weight of mono-tuber, followed by phosphorus, nitrogen was the smallest. But the interaction was significant to the weight of mono-tuber between nitrogen and phosphorus. (4) Potassium had the most significant influence on the formation of dry matter, followed by nitrogen. Phosphorus was not significant. But the interaction of N-P and N-K. had significant influence on the content of dry matter. As to starch content, three factors were not significant. The first was nitrogen to the content of vitamin C, followed by potassium and phosphorus. And the content of vitamin C would decrease if phosphorus was fertilized excessively. As for protein content of tuber, phosphorus was the most important factor. The second was nitrogen and the last was phosphorus. But the interaction of P-K had significant impact on the formation of protein.(5) Through the simulation and forecast of computer, we can find out the optimal combination of NPK fertilizer about soilless cultivation in theory. The combination was following:N 248～296mg/L, P 62～68mg/L, K 480～560mg/L, and the proportion of NPK was 4.18 : 1 : 8.00.