Effects of Different Potassium Fertilizers and Fertilization Times on Yield and Quality of Leafy Vegetables

We studied the effects of different potassium fertilizers(KCl and K2SO4) and fertilization times on yields and quality of lettuce and Chinese cabbage. The results showed that, the yields of lettuce and Chinese cabbage were increased while the potassium fertilizers were applied at different periods compared to the treatment taking potassium fertilizer as base fertilizer, and KCl was better than K2SO4for increasing yield of lettuce, while K2SO4was better for increasing yield of Chinese cabbage. Soluble sugar content of lettuce was decreased. Vitamin C content of Chinese cabbage was increased in all treatments, while nitrate content was decreased, in addition, the amino acid content was increased except for the treatment taking K2SO4as base fertilizer(K2-1 treatment). Total nitrogen content of Chinese cabbage changed little. Total phosphorus, potassium and chloride contents of lettuce were all increased, and total sulfur content of lettuce leaves was increased except for K1-3 treatment. Total sulfur content of lettuce stem was increased except for K2-4 treatment. Total phosphorus content of Chinese cabbage was increased by 15.6% in the treatment K1-4, while those of other treatments were decreased. Total potassium content of Chinese cabbage was increased, and K2SO4was better than KCl. The K1-4 treatment had highest total utilization rate of potassium fertilizer.