INFLUENCE OF POTASH ON HEAD YIELD AND QUALITY OF CHINESE CABBAGE

A field trial was conducted for investigating the effects of K fertilization on production of head yield and head quality of Chinese cabbage (Brassicd campestrisL). The res! results indicate that K application can enhance head yield of Chinese cabbage through increasing shoot biomass and proportion of head yield in shoot biomass. And it also can be found that head yield is significantly correlative to the amount of dry matter accumulated in it with the coefficients of 0.971 (KC1) and 0.985* * (K2SO4), which means that the production on head yield is based on the accumulation of dry matter in head. The test results also show that K dressings can improve the head quality by increasing the contents of rough protein, vitamin C, all amino acid as well as essential amino acid; reducing the content of NO3- in vein and mesophyll, and decreasing the ratio of vein fresh weight to mesophyll fresh weight in head. The growth rate of K fertilizer on head yield declines with the increase in the dose of K supply, but with the analysis of economic benifits, the adequate rate of K2O for Chinese cabbage is in 180 to 240kg/hm2, which can be regarded as a reference to K fertiliation in production of Chinese cabbage.