Effects of Fertilizer and Density on Photosynthetic Characteristics and Yield of Potato

Densities and different fertilizers of nitrogen(N),phosphate(P),and potassium(K) were tested in field experiments of three replications using 4 factors 5 levels versatile regressive rotary compound design.The results indicated that photosynthetic rate of potato leaves and plot yield showed significant regression relations with different combinations of fertilizer and density;The effect of fertilizer and density on photosynthetic rate of potato was K N P density;The effect on plot yield was K P N density;There was significant positive correlation between photosynthetic rate of potato leaves and plot yield.Too low or too high N,P,K may inhibit photosynthetic rate of potato leaves.The photosynthetic rate of potato leaves decreased with the increase of potato density,and the rate accelerated.Interactions of N × P,N×density,and K×density had positive influence on photosynthetic rate of potato leaves.Interactions of N×P,N×K,and P×K had positive influence on tuber yield.The optimal combination for the maximum photosynthetic rate of potato leaves was N 172.5 kg·hm-2,P2O5 112.125 kg·hm-2,K2O 90 kg·hm-2,and density of 60 000 plants·hm-2.The optimal combination for the maximum theoretical yield was N 172.5 kg·hm-2,P2O5 112.125 kg·hm-2,K2O 67.5 kg·hm-2,and density of 60 000 kg·hm-2.