The three elements of fertilizer have different effects on the growth and development of wheat and cannot replace each other. Lack of coordination or imbalance will affect the growth of wheat. Nitrogen is a component of nitrogen-containing substances such as amino acids, protein, enzymes and nucleic acids, and it is the main component of wheat cell protoplasm. Nitrogen fertilizer can promote the growth of roots, stems, leaves and tillers of wheat, increase the green area and chlorophyll content, and strengthen photosynthesis. The most obvious change after applying nitrogen fertilizer is the deepening of green leaves. Appropriate amount of phosphorus can promote tillering at tillering stage, increase the number of spikelets and improve the seed setting rate at young panicle differentiation stage. Maintaining proper nitrogen nutrition in the late growth stage can increase grain weight and improve grain quality. If nitrogen nutrition is reasonable, wheat plants will be strong and grow well; Under nitrogen deficiency, leaves turn yellow, plant growth is inhibited, stems and leaves are small, branches are few and yield is low; Excessive nitrogen can easily lead to excessive growth, lodging, delayed maturity, increased cost and waste of plants.
Phosphorus is a component of nucleotides, nucleic acids and phospholipids. It is not only an important part of wheat nucleus, but also directly participates in respiration and photosynthesis, and participates in the synthesis, decomposition and transportation of carbohydrates. Adequate phosphorus is beneficial to tillering, rooting, ear development and grain filling of wheat, which can promote maturity and increase grain weight. In cold areas in winter, proper application of phosphate fertilizer can also enhance the safe wintering ability of wheat. When phosphorus is insufficient, root development is inhibited, tillering is reduced and leaves are dark green and dull. When phosphorus is seriously deficient, leaves are purple, photosynthesis is weakened, heading and flowering are delayed, grain filling is abnormal, 1000-grain weight is reduced, and quality is poor, which affects yield.
Potassium is not involved in the composition of organic molecules in plants, but it is an activator of many enzymes. In addition, air holes should be opened. Potassium can promote the formation and transformation of carbohydrates, so that sugar in leaves can be transported to growth organs. Potassium can enhance the resistance of wheat to low temperature, high temperature and drought. Potassium can also promote the development of vascular bundles, make stems tough and improve lodging resistance. When potassium is insufficient, the growth of wheat plants is delayed, the stems are short and brittle, the mechanical organization and transportation organization are underdeveloped, and it is easy to lodging; Drought resistance and cold resistance are weakened; Tillering ability and photosynthesis are limited; The leaves turn green, and there are dead tissues with large and small spots, and the lower leaves dry up early; Poor root growth, early heading, few grains per ear, insufficient filling, low yield and poor quality.
The effects of three elements of fertilizer on wheat growth and development are not isolated from each other, but interrelated and interactive. Phosphorus can promote the absorption of nutrients such as nitrogen, and potassium can also promote the transformation of nitrogen and phosphorus. Only when nitrogen, phosphorus and potassium are properly matched with other essential nutrients can greater fertilizer efficiency be exerted.