Effect Of N,P,K On The Growth And Yield Of Chinese Yam

Chinese yam is a kind of important special local vegetable that can earn foreign exchange and has effect of medicine and tonic. But the research about fertilization and mineral nutrition absorption and distribution in Chinese yam is rare. The phenomenon of applying fertilizer blindly exists on production, which influence yield and quality very much, and decrease the benefit of Chinese yam production. For this reason, this paper studied the effect of nitrogen, phosphorus and potassium on Chinese yam's growth and development, yield, absorption and distribution of nutrition element. In the meantime, we also studied the morphological characteristics changes of Chinese yam. Analyzed by computer, we determined the optimizations of Chinese yam fertilizer, and offered the scientific theoretical foundation for applying fertilizer rationally in Chinese yam. The main results were as follows:1. N, P, K affected growth of Chinese yam. In a certain range, plant growth increased when the quantity of fertilizer increased. But if the quantity were too much, the growth would decrease.2. N, P, K affected photosynthesis ability of Chinese yam. When the ratio of N and K is reasonable, photosynthetic rate are high. The period of high light effect is long. Photosynthetic rate in later period of tuber vigorous growth stage deceased slowly and photosynthetic matter accumulated more.3. N, P, K affected the Chinese yam's ability of utilizing nutrition. It also affected the absorption and distribution of mineral nutrition. When usage of N,P and K is reasonable, the absorption amount of N, P, K, Ca, Mg, Fe, Mn, Cu and Zn is increased too. The amount which distributed to tuber was also augmented , which helped to improve economic coefficient.4. N, K affected the yield of Chinese yam. If the proportion of N and K is reasonable, yield would be high. K had more influence than N, and N, K had district mutual effect. In this experiment, if usage of N and K are below 19.91kg/667m2^ 47.40kg/667m2, yield would increase with the increase of fertilizer. But if used too much fertilizer, yield would decrease. The fertilizer plan of highest yield is N 16.27kg/667m% K2O 52.86kg/667m2, yield could reach 2768.72 kg/667m2.5. Phosphorus also affected the yield of Chinese yam. In this experiment, the optimal usage of P is 15Kg / 667m2, yield could reach 2754.7kg/667m2.