Because NPK fertilizers contain nitrogen, phosphorus, and potassium, they have different promotion effects on plants. Among them, the nitrogen element is mainly to increase chlorophyll and strengthen vegetative growth; the phosphorus element is mainly to promote the formation of flower buds, the flowers are large and colorful, and the fruits are early-maturing; the potassium element is mainly to improve the ability of resistance to diseases and insect pests, cold resistance, drought resistance and lodging resistance.