Stage of nutrient absorption by plants: Plants need to go through different stages of growth and development in the whole growth and development cycle (from seed germination to new seed formation), and each stage of growth and development has different nutritional characteristics, showing different demands for nutrient types, quantities and proportions, which is the stage of nutrient absorption by plants. Although plants absorb nutrients in stages, the general trend is that the absorption at seedling stage is small and the intensity is small; When the growth is vigorous, especially when vegetative growth and reproductive growth coexist, the quantity and intensity of absorbed nutrients increase obviously; When it is close to maturity, the absorption will gradually decrease. However, at any stage, the effect curve between plant growth rate and nutrient supply (that is, the growth effect curve) has three clear regions.

Relationship between nutrient supply and plant growth