What is the application principle of foliar fertilizer?

To clarify the principle of foliar fertilizer, we must first clarify the leaf structure. The basic structure of leaves is leaves, petioles and stipules. Leaves include epidermis, mesophyll and veins. Mesophyll is generally divided into palisade tissue and sponge tissue (C3 plants are different from C4 plants).

Characteristics of angiosperm leaves: epidermis is divided into upper epidermis and lower epidermis, which is generally composed of a layer of cells. There are pores on the epidermis, which are generally composed of two kidney-shaped guard cells. The leaf structure of monocotyledonous Gramineae is basically the same as that of common angiosperms. But the epidermis has two kinds of cells, rectangular and square. Stomatal guard cells are dumbbell-shaped, and there are subsidiary guard cells outside the guard cells.

Generally speaking, stomata are open during the day and closed at night. When foliar fertilizer is sprayed, the fertilizer enters from stomata and is absorbed by plants.

According to their functions, foliar fertilizers can be classified into the following four categories. The first kind of compound foliar fertilizers, such as Tianda 2 1 16, chitosan oligosaccharide, etc., contain marine active components and also contain various trace element fertilizers necessary for plant growth. It can activate the expression of plant resistance genes and strengthen plant nutrition.

The second category: nutrient foliar fertilizer. This foliar fertilizer is rich in nutrients such as nitrogen, phosphorus, potassium and trace elements. Its main function is to provide various nutrients for crops and improve the nutritional status of crops, and it is especially suitable for supplementing various nutrients in the later period of crop growth. The third category: regulated foliar fertilizer. This foliar fertilizer contains substances that regulate plant growth, such as auxin and hormone, and its main function is to regulate the growth and development of crops. Suitable for the prophase and metaphase of plant growth. The fourth category: biological foliar fertilizer, which contains microorganisms and metabolites, such as amino acids, nucleotides, nucleic acids and so on. Its main function is to stimulate crop growth, promote crop metabolism, and reduce and prevent the occurrence of pests and diseases.