Nitrogen is the main component of protein, which plays an important role in the growth of stems and leaves and the development of fruits, and is the nutrient element most closely related to yield. Before the first ear expanded rapidly, the plant's absorption of nitrogen gradually increased. Nitrogen is an integral part of chlorophyll synthesis, and both chlorophyll a and chlorophyll b contain nitrogen-containing compounds. Chlorophyll is a factory where plants make carbohydrates. Nitrogen can synthesize protein and promote cell division and growth.

2. Phosphorus

Phosphorus fertilizer can promote tomato flower bud differentiation, early flowering and fruiting, promote seedling root growth and improve fruit quality. When phosphorus is deficient, buds and roots grow slowly, plants are short, leaves are dark green and dull, and the back is purple.

Phosphorus application can promote the normal metabolism, growth and development of plants, and improve their cold resistance and drought resistance. Because phosphorus is related to the metabolism of sugar, protein and fat and their mutual transformation, it is necessary to plant phosphate fertilizer for grain crops, bean crops and oil crops.

3. Potassium

Potassium can promote the health of plant stems, improve fruit quality, enhance the cold resistance of plants, and increase the contents of sugar and vitamin C in fruits. Like nitrogen and phosphorus, potassium deficiency symptoms first appeared in old leaves.

When potassium supply is insufficient, carbohydrate metabolism is disordered, photosynthesis is inhibited and respiration is enhanced. Therefore, when potassium is deficient, the plant's stress resistance is weakened, and it is vulnerable to diseases, and the fruit quality is reduced and colored. The demand of potassium fertilizer for melons, fruits and tomatoes is mainly in the period of rapid fruit expansion.

Extended data

Nitrogen, phosphorus, potassium and other nutrients in the soil can not meet the needs of crop growth, and need to be supplemented by applying fertilizers containing nitrogen, phosphorus and potassium. In addition to chlorine, other trace elements need to be combined with micro-fertilizer application.

Fertilizers are generally inorganic compounds, and only urea [CO(NH2)2] is an organic compound. Any chemical fertilizer containing only one nutrient element and marked content is called unit fertilizer, such as nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer.

Any chemical fertilizer that contains two or more of the three nutrient elements of nitrogen, phosphorus and potassium and can indicate its content is called compound fertilizer or mixed fertilizer. Grade is the main index of fertilizer quality. Refers to the percentage of effective nutrient elements or their oxides in chemical fertilizer products.

Baidu encyclopedia-potassium

Baidu encyclopedia-phosphorus

Baidu encyclopedia-nitrogen