Essential elements and their physiological functions in Cymbidium plants

In addition to the water content of the orchid plant, the remaining substance is in the matter. It contains organic matter and ash. Organic matter accounts for 90% of dry matter, mainly including carbon, hydrogen, helium and oxygen. During the determination and treatment, they are released as carbon dioxide, water vapor, free nitrogen and other substances. Ash is derived from the mineral salt absorbed by the plant in the cultivation substrate, and the elements it contains are mineral elements. Although nitrogen is not a mineral element, for orchids, it is also absorbed from the cultivation substrate in the form of inorganic salts, so it is also included in the mineral elements in the study of the physiology of Chinese orchids.

Orchids need more than a dozen mineral essential elements, of which a large number of elements are carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur and so on. The trace elements with less demand are iron, boron, copper, zinc, manganese, chlorine, steel and so on. Hydrogen and oxygen are obtained from plants from water, carbon from the atmosphere, and mineral elements and nitrogen from cultivation media.

The physiological functions of essential elements are multifaceted. Some elements are directly involved in the composition of protoplast or other parts, such as helium is one of the constituent elements of amino acids, proteins, chlorophyll and many enzymes, and phosphorus is an important constituent element such as nucleic acid and phospholipid. The salt formed by calcium and pectic acid is the main component of the gel layer in the cell wall, and magnesium is the constituent element of chlorophyll molecules. Some elements are the components of the enzyme or the regulator of the enzyme, such as iron is the auxiliary component of cytochrome oxidase, catalase and peroxidase, copper is the auxiliary component of ascorbate oxidase, potassium ion acts as an activator for the enzyme, etc. Phosphorus can promote the synthesis, mutual transformation and transport of carbohydrates, proteins and fats in the body, indicating that some elements can play a certain role in the transformation and transportation of substances.

Because all kinds of essential elements have specific physiological effects on plants. Therefore, the orchid plant will show some unique symptoms when it lacks or absorbs too much elements, such as the plant will be short and the leaf color will turn yellow when the plant is deficient in nitrogen, and the absorption of excess nitrogen will grow and droop, affecting the ornamental value. Especially for the national orchid varieties of line art, excessive nitrogen may lead to the fading of line art or the color is not obvious. It mainly increases the amount of chlorophyll and masks other pigments.

Phosphorus is a component of nucleic acid, phospholipid and many enzymes, which is actively involved in intracellular material metabolism and energy metabolism in plants. It can promote flowering and fruiting and improve the cold resistance and drought resistance of the plant. Therefore, when phosphorus deficiency occurs, plants, including roots, may be seriously inhibited. The plant is relatively short and weak, the pseudo-corm is small, and the root is underdeveloped and slender. Therefore, in the process of cultivation, it is necessary to strengthen the supplement of phosphorus, especially the varieties of Magnolia and odd flowers, in order to promote their root system development and promote the "heading" of pseudobulbs (refers to the enlargement of pseudobulbs), so that odd flowers can bloom easily. The line art class enhances the drought resistance and can prevent the thread part of the leaves from being burned by the sun. Because of the developed root system and large pseudobulm, other orchid varieties will also promote the germination of new buds and improve the speed of reproduction.

Potassium is the activator of some enzymes, which actively participates in a variety of physiological activities of cell protoplasm, which can promote the metabolism of protein and improve the hydration of cell colloid. When potassium was suitable, the plant was stout, the pseudocorm enlarged obviously, and the leaf was thick and hard. If potassium deficiency makes the plant short, weak and slender, the young leaves are easy to wilt. The edge of the old leaf turns brown and withered, and the leaf is thin and weak. Therefore, in order to make the orchid plant stout and improve the disease resistance of leaves, especially in the period of new buds and new leaves, potassium should be strengthened, especially in Guangxi and Vietnam, because the leaves are thin and soft and easy to grow, so the input of potassium should be strengthened. in order to increase the leaf thickness and promote sturdiness.

Magnesium is not only the constituent element of chlorophyll, but also the activator of some enzymes. Orchids planted in places with strong light often need magnesium to promote the production of chlorophyll. If the lack of magnesium leaves are easy to aging, can not be connected for many generations, affecting the competitiveness of commodities in the market. At the same time, flowering is also suppressed, and the color of the flowers is pale and not bright. However, because magnesium is the main component of chlorophyll, when cultivating orchids with green moss spots or "rotten bottom", the green pigment may be more obvious and affect the ornamental value of line art, which must be paid attention to in cultivation. What is worth trying is that some post-epiphany or post-bright varieties of thread art, such as some varieties of "Dashimen" and those of Daming Orchid, should be specially controlled to supplement some magnesium elements in order to prevent the line art from fading. promote the thread art to change from Hou Ming to Qianming or improve, so that the art color can emerge.

Calcium can promote the protoplast to the gel state and is one of the constituent elements of the cell wall. In the cultivation of Chinese orchid, calcium can make the plant firm, the head strong, the meristematic ability increased and the root absorption capacity increased. If the lack of calcium, the plant becomes weak, the performance of overgrowth, premature senescence. The young leaves are fragile and yellowed, the cells of the sharp meristem are easy to rot, and the pseudocorm knot is not obvious. Therefore, measures are taken to supplement calcium in the cultivation of Cymbidium. Generally, bone powder or shell powder is used for topdressing, and the effect is easy to achieve. Because these bone powders contain a large amount of calcium and need a corresponding process of decomposition, it will not cause fertilizer damage to orchid plants, so it is a common method to add calcium in large-scale cultivation of Chinese orchids. Especially when the orchids cultivated in pond mud are transferred to other cultivation substrates, because the old ones are easy to rot, it is of great significance to strengthen the supplement of calcium, improve the meristematic ability of reporting lines and improve the product quality.

Sulfur is one of the main elements that make up proteins. If sulfur is deficient, the growth of the plant will be inhibited in the later stage, and the pseudo-corm is small and sparse. In order to promote the late growth of the orchid plant, the addition of sulfur can be enhanced by making the pseudocorm head earlier. However, sulfur may cause the yellow leaves of some early new buds with yellow and red pigments to turn green earlier, thus reducing the appreciation value in the appreciation of magnolia. Therefore, these varieties should be treated carefully when applying sulfur. Even some varieties with lines in the veins may dim the color when the sparse elements are strengthened.

Iron is the constituent element of some enzymes, such as cytochrome oxidase, catalase and so on. Without iron, the growth of plants is generally abnormal and weak, and the growth of pseudocorms and roots is inhibited. Therefore, in order to ensure the normal growth of orchid plants, promote the development of newspaper lines and "knot" early, iron should be properly added in the process of cultivation. However, the line magnolia has the artistic effect of pursuing obvious yellow or white lines on the leaves. If the cultivation substrate contains too much iron, it may cause the color of the line art to return to green and lose the value of cultivating the line magnolia. Therefore, in order to make some varieties whose thread art is not obvious, we can choose the cultivation substrate with less iron element or not to add iron element as soon as possible, and we might as well try its effect.

Manganese is the activator of some enzymes, which is closely related to the oxygen evolution reaction in photosynthesis. Due to the lack of manganese, the plant is short and thin, the growth of pseudocorm is weak, and the number of flowering is reduced. Therefore, the supplement of manganese should be strengthened in non-linear arts and varieties that pursue flowering effect. However, due to the manganese element can make the yellow and white line art of the leaves green, so that the color is not bright, so the addition of manganese element in the online magnolia should be enough.

Boron has corresponding significance for material transport, biofilm permeability and differentiation of transport tissue in plants. The lack of shed can make the plant short and delicate, the leaf tip dry, the new leaf rough, the leaf vein easy to break, the meristem inactive, the root tip dead and the flower easy to fall off. The cultivation of orchid cultivars should strengthen the addition of boron element. Boron deficiency can make the leaves red. When the online Yilan pursues the color effect, it might as well limit the absorption of boron by the orchid plant, so as to improve the appreciation value of Yilan.

Copper is a component of oxidase, which can improve the drought resistance of plants. However, the lack of copper will make the orchid plant stunted, the plant slender and prone to disease. Therefore, in order to improve the drought resistance of the plant and promote its normal development, copper should be properly supplemented in the process of cultivation. However, the lack of copper can lead to green deficiency and yellowing of leaf tips, so the absorption of copper by orchid plants should be properly restricted during the cultivation of online magnolia in order to maintain obvious or even strengthen the artistic color.

Zinc is not only the component of some enzymes, but also the activator of some enzymes. Therefore, the lack of zinc affects the composition and activity of enzymes, resulting in abnormal plant growth, short and delicate. However, the lack of zinc will make the leaves yellowing, so the addition of zinc should not be too urgent in this respect, so as not to affect the effect of the performance.

The lack of any essential element in the plant will show certain physiological symptoms. However, some external factors, such as the virus in the disease, cause yellowing, and even the conditions of the cultivation substrate will affect the absorption or transport of nutrients by plants, and will also cause the disease of element deficiency. The symptoms caused by insect toxins caused by some pests are often similar to nutritional deficiencies and must be distinguished so that measures taken in mineral nutrition management can be effective. (Liu Zhongjian)