EFFECTS OF NITROGEN AND POTASH FERTILIZERS ON THE YIELD AND QUALITY OF LEAFY VEGETABLES

A field experiment was carried out to study the effects of N and K fertilizers on the yield and quality of three leafy vegetables. Application of N increased the yield of Chinese cabbage and celery by 22.7%～36.5% and 12.2%～44.6%, respectively; while K application increased the yield of Chinese cabbage, Cabbage and Celery by 7.8%～22.8%, 14.1%～32.7% and 34.6%～54.1%, respectively. The relationship between N rate and the yield of the 3 vegetables could be well described with quadratic regression equations. A significant linear relationship was found between K rate and the yield of Chinese cabbage and Cabbage, while a significant quadratic regression relationship was found to exist between celery yield and K rate. N application enhanced nitrate content of all the three vegetables studied and low K rate increased nitrate content of Cabbage by 4.4% and high K rate reduced it by 33.3%～41.1%. The effect of N and K on the nutritional quality varied with vegetable species. Vitamin C was highest in Chinese cabbage and lowest in Celery, and soluble sugars and amino acids were highest in Cabbage and lowest in Celery.