Effects of Combined Application of N,P and K on Photosynthesis of Flag Leave During Grain Filling Period for a Hybrid Rice,Liangyou 108

By the method of quadratic orthogonal rotational combination design with three factors,studies were conducted on the effects of different application levels of N,P and K fertilizers on photosynthetic characteristics of flag leaves for a hybrid rice,Liangyou 108.A regressive equation was established between photosynthetic rate and the application level of fertilizer.The result indicated that nitrogen,potassium and phosphorus fertilizers could significantly enhance photosynthetic rate of flag leaves.The effects order were phosphorus nitrogenpotassium.P fertilizer had the most significant effect on the photosynthetic rate among N,P,K and there was obvious interaction between P and K.In the moderately fertilized rice field,the optimum fertilization formulation was: N 190.2-240.6 kg/hm2,P2O5 50.8-83.6 kg/hm2,23.8-363.0 kg/hm2 K2O,and the photosynthetic rate could reach the value of 20.5 μmol/(m2·s).