Relationship between Plant Nutrition Principle and Fertilization of Orchid

When orchid friends discuss the cultivation techniques of orchids, there are often the following situations about the fertilization of orchids:

First, do not dare to apply nitrogen fertilizer, for fear that after the application of nitrogen fertilizer, the plant will grow tall, the leaves will be long and wide, and the leaves will walk on the leaves.

Second, partial application of phosphorus and potassium fertilizer, the main application is potassium dihydrogen phosphate, it is considered that the application of phosphorus and potassium fertilizer plants will grow well, the leaves will not walk. However, due to the lack of nitrogen, the growth of the orchid plant was short, the leaves were yellowish green, stiff, lack of luster, the new buds did not grow up, the whole orchid plant had more cellulose, and the aging phenomenon appeared.

Third, fertilization is not weighing, do not know the amount of fertilizer, easily grasp the matter, add compound fertilizer or potassium chloride fertilizer on the plant material, after watering, because the fertilizer is too thick, the leaf sheath of the orchid plant turns black, and the growth of the plant stops. Pull up the orchid plant with your hand and observe that the root has turned black or moldy.

Judging from the above, it is all due to the lack of understanding of the role of several major fertilizers. Therefore, this paper introduces the effects of nitrogen, phosphorus and potassium on plant growth, which can be used as a reference for orchid friends when applying fertilizer.

The role of nitrogen: many important organic compounds in plants contain nitrogen. Nitrogen is an important part of protein. The content of nitrogen in protein accounts for 16%. The protoplasm in cells is mainly composed of proteins. Proteins exist in every living cell and are the material basis of the life process. No protein can be formed without nitrogen. Without protein, there will be no protoplast and no life.

Chlorophyll, enzymes, vitamins and plant hormones (such as gibberellin) in plants all contain nitrogen. If there is no or lack of nitrogen, the formation of these compounds will be affected. As far as the formation of chlorophyll is concerned, when the plant is deficient in nitrogen, the chlorophyll in the body decreases, or even can not be formed, so that the leaves are yellowed, the intensity of photosynthesis is weakened, and the protein formation is also limited. When the nitrogen supply is sufficient, the leaves are dark green, which promotes the formation of chlorophyll and photosynthesis. At the same time, it can also promote the assimilation of nitrogen and the formation of protein, so that the cells grow rapidly and the stems and leaves flourish. When the nitrogen nutrition of orchids is sufficient, the pseudobulbs will also expand, thus storing more nutrients, so orchids should also be properly applied nitrogen fertilizer. However, if there is too much nitrogen supply, the plant grows too luxuriantly, and only a small amount of carbohydrates make up cellulose, so the plant has the phenomenon of overgrowth, soft leaves and easy infection. Diseases and insect pests.

Commonly used as nitrogen fertilizer are: sulfate hinge, urea, ammonium nitrate, ammonium phosphate, peanut bran. Human and animal urine, etc.

The role of phosphorus: phosphorus exists in plants in the form of organic and inorganic compounds. In normal growing plants, phosphorus is most abundant in meristem and is used to form nuclear proteins and other phosphorus compounds. Nitrogen and phosphorus are the most important compounds in protoplasm. they participate in various processes of transformation of organic matter in cells, and participate in the process of cell division and reproduction. Nuclear proteins and other phosphorus compounds (such as phospholipids) are formed during cell division and organ growth.

Phosphorus also exists in many enzyme molecules. Phosphorus is involved in the metabolism of carbohydrates in plants, and almost all compounds produced by photosynthesis contain phosphorus. The synthesis of starch and sucrose in plants requires the participation of phosphorus, and phosphorus also promotes the transport of carbohydrates in plants. Promote plant respiration. Phosphorus is closely related to the formation of amino acids and proteins in plants. Due to the inseparable relationship between phosphorus metabolism and nitrogen metabolism in plants, most of the phosphorus in the old leaves is transferred to the growing tissues during phosphorus deficiency (proved by radioactive phosphorus studies, phosphorus can be transferred at a high speed, so phosphorus deficiency is first shown in the old leaves). The absorption of ammonia compounds is also limited when phosphorus deficiency, so the effect of nitrogen fertilizer alone will not be very good in the case of phosphorus deficiency. If nitrogen fertilizer and phosphorus fertilizer are applied together, good results can be obtained.

Commonly used as phosphate fertilizer are: potassium dihydrogen phosphate, ammonium phosphate, calcium superphosphate, bone powder and so on.

The role of potassium: potassium in young and active growing organs of plants, such as buds, young leaves, root tips have a large amount of potassium, and the protein content in these organs is also high, potassium in plants is related to the distribution of protein. Potassium is different from nitrogen and phosphorus, potassium does not participate in the composition of important organic matter in plants, most of them exist in plants in a free state, and these potassium can be extracted from plants with water. Potassium in senescent leaves of plants can be transferred to young tissues, so there is little potassium in old leaves. When the supply of potassium is sufficient, more nitrogen enters the plant and a large amount of protein is formed. Potassium enhances the metabolism of carbohydrates, resulting in the formation of more amino acids, as potassium enhances the activity of proteases that promote protein synthesis. Potassium is closely related to the synthesis and transport of carbohydrates in plants and the conversion of monosaccharides into disaccharides and polysaccharides. The synthetic or accumulated carbohydrates are stored (such as pseudobulbs of orchid storage organs). So the potassium content in storage organs is very rich. Sufficient potassium supply can promote the good development of mechanical tissue, increase the cellulose in stems and leaves, strengthen the plant and have strong disease resistance. When potassium is deficient, monosaccharides accumulate in the leaves, which hinders the speed of photosynthesis, reduces the intensity of photosynthesis, and affects the formation and transport of carbohydrates.

Used as potash fertilizer are: potassium sulfate, potassium nitrate, potassium chloride, potassium dihydrogen phosphate, plant ash and so on.

Plant physiologists in Guangdong have done some physiological and biochemical studies on Cymbidium in recent years. It is believed that the pseudobulb stores a lot of water and nutrients. The nitrogen nutrition of mixed application of nitrogen and nitrate nitrogen was better than that of nitrate nitrogen alone. When phosphorus nutrition was sufficient, the activity of acid phosphatase decreased. After the improvement of potassium nutrition level, the leaf growth is good, the incidence is less, the number of flowers is also more, different potassium levels, phosphopyruvate esterase and potassium are positively correlated, while nitrate reductase is also increasing, indicating that with the improvement of potassium level, the utilization of nitrogen is also increased. It shows that nitrogen, phosphorus and potassium are essential nutrient elements in the growth and development of orchids as well as other plants.

The role of calcium, magnesium and other trace elements: calcium can stabilize the structure of biofilm, maintain cell integrity, and promote cell elongation and root growth. Magnesium is an indispensable element for the synthesis of chlorophyll, which increases and promotes photosynthesis. Boron is not involved in the composition of enzymes, and no boron-containing enzymes have been found so far. Boron is mainly distributed in floral organs such as ovary and stigma of plants and plays an important role in the formation of reproductive organs. Boron deficiency often causes the death of meristem, which may be related to the involvement of boron in long-distance sugar transport. Lack of boron bow is ashamed of cotton falling flowers, peanuts "have shell but no kernel", root growth point stops growth and necrosis. Iron, platinum, zinc, manganese, copper and other trace elements, their main nutritional function is as the basic components or activators of enzymes in cells. For example, the rhizobia of leguminous plants can fix molecular nitrogen in the air into ammonia, and then synthesize organic nitrogen-containing compounds from ammonia, its function is with the help of nitrogenase, and nitrogenase contains iron and these two trace elements can play the role of nitrogen fixation, if there is no iron, silver, nitrogenase can not fix nitrogen.

Commonly used as trace elements for plant nutrition are: calcium superphosphate, bone powder or lime, magnesium sulfate, boric acid or borax, ferrous sulfate, manganese sulfate, zinc sulfate, copper sulfate, key acid or silver acid hinge and so on.