How does photosynthesis in orchids take place

OrchidsPhotosynthesis mainly relies on the chlorophyll in the leaves to absorb light energy, using carbon dioxide and water to produce organic matter and release oxygen, while converting light energy into chemical energy stored within the organism. Its main role is to convert inorganic matter into organic matter and store it in the various organs. From this we can understand that light isorchidsthe key to carrying out photosynthesis, and is the essential condition for maintainingorchidslife, and the driving force for orchid growth. I. The mechanism of photosynthesis in orchids: TheFlower'sphotosynthesis of orchids is not a simple process; it can be divided into two major steps: the light reaction and the dark reaction. The light reaction can only proceed in the presence of light; the dark reaction can proceed with or without light. Under strong light, the photosynthetic rate is affected by temperature within a certain range, accelerating as temperature rises, and the light reaction proceeds rapidly. The entire process of the light reaction will be limited by temperature and the dark reaction. In the light reaction, water is decomposed by the light energy absorbed by chlorophyll, that is, light with the help of chlorophyll splits water into hydrogen atoms and hydroxyl atoms, and the hydroxyl atoms then form water and release oxygen. The next step of photosynthesis is the dark reaction, which is the fixation and reduction of carbon dioxide. The hydrogen atoms split off in the light reaction use chlorophyll as a carrier and are transferred to carbon dioxide molecules through various compounds. Before carbon dioxide can be reduced, it must first be fixed into some kind of compound, and only then can it be reduced by hydrogen into organic matter. II. The products of photosynthesis in orchids: The direct products of photosynthesis in orchids are carbohydrates, including monosaccharides, disaccharides and polysaccharides, among which sucrose and starch are the most common. There are also proteins, fats and organic acids, but these substances account for a relatively small proportion and are only re-synthesized through the intermediate products of carbohydrate metabolism. These substances will be further synthesized into various other organic compounds, such as nucleic acids, auxins, lignin, vitamins, alkaloids, anthocyanins and so on. The quantity of the various products of photosynthesis has a certain relationship with the age of the plant, the light conditions and the status of nutrient elements. Young tender leaves produce more protein, so they are more drooping and soft. As light increases, more carbohydrates are produced, so the leaves are firmer and more likely to "set heads". Under red light more carbohydrates are synthesized; under blue light more protein is synthesized. As nitrogen nutrition increases, more protein is produced; conversely, more carbohydrates are produced. Therefore, under conditions of abundant nitrogen and weak light, more protein is formed in orchid leaves, which easily causes the orchid plant to grow leggy, with soft and lodging leaves. III. Factors affecting photosynthesis in orchids: TheFlower'sphotosynthesis of orchids, like other physiological processes, is affected by a series of internal and external factors. The degree of aging of orchid organs, the chlorophyll content in the body and the external environment all have a direct influence on theFlower'sphotosynthesis of orchids. Here we mainly analyze the influence of the external environment on orchid photosynthesis. 1. Light intensity: Light is the key to photosynthesis and the energy source of photosynthesis; without light, orchids cannot carry out photosynthesis. Light intensity is closely related to photosynthetic intensity. The commonly used unit of light intensity is lux, which can be measured directly with a light meter. On a clear summer day, the light intensity on bare ground is above 100000 lux; on a clear winter day the light intensity on bare ground is about 25000 lux; while on rainy days the light intensity is less than 1/10 of that on a clear day. (The above data are for the Jiangsu-Zhejiang region; light intensity also differs in different regions.)Cymbidium goeringii.Cymbidium tortisepalumand Chun Jian are relatively suitable at a light intensity of 6000~10000 lux,Cymbidium faberiandFour SeasonsOrchidrequire somewhat higher, 9000~14000 lux,Cymbidium sinenseis lower, 4000~6000 lux, and for variegated-leaf orchids the light intensity should be correspondingly reduced. Under normal circumstances, orchids can carry out photosynthesis under relatively weak light, and the weaker the light, the weaker the photosynthesis; if the light intensity increases, photosynthesis also strengthens accordingly. But when the light intensity reaches a certain level, and the light intensity is increased further to the light saturation point, photosynthesis no longer strengthens accordingly; if the light intensity continues to increase beyond this point, the photosynthesis of orchids will decline, and at the same time strong light often leads to high temperatures, which easily causes a lack of water in the leaves, closure of the stomata and thus an insufficient supply of carbon dioxide. It can be seen from this that Chinese orchids are shade-tolerant plants, and when the light intensity is relatively strong, shading is needed to reduce the light intensity so that orchids can carry out photosynthesis normally. 2. Carbon dioxide concentration: Carbon dioxide is the main raw material of photosynthesis, and its content will directly affect the progress of photosynthesis. Under normal circumstances, the most suitable carbon dioxide concentration for orchid photosynthesis is 0.1%, while the carbon dioxide content in the air is usually around 0.03%. Within a certain range, appropriately increasing the carbon dioxide concentration in the air can significantly increase photosynthesis. When cultivating orchids in a greenhouse, the method of carbon dioxide fertilization can be applied to increase the carbon dioxide content in the air. (I have not tested this myself, so I do not know how effective it is; I hope orchid friends who have used it can introduce it in detail.) In addition, fermentation of organic matter can also increase the indoor carbon dioxide concentration. However, when the carbon dioxide concentration in the air is too high, it is also unfavorable to orchid photosynthesis; when the concentration exceeds 1%, it will cause poisoning of the orchid protoplasm and closure of the stomata, thereby inhibiting photosynthesis. At this time, if the light intensity is increased, the usable concentration of carbon dioxide can be relatively raised. Therefore, ventilation, exhaust and lighting equipment should be installed in the orchid room. 3. Temperature: Under normal circumstances, orchids can carry out photosynthesis normally at 5~36 degrees, and the most suitable temperature is 15~30 degrees. Below 5 degrees, photosynthesis is inhibited. Starting from the lower temperature limit, photosynthesis strengthens as temperature rises, but when it exceeds 36 degrees, photosynthesis will be very weak or even stop. The influence of temperature on orchid photosynthesis is directly related to light intensity and carbon dioxide concentration; within a certain range, under conditions of higher light intensity and higher carbon dioxide concentration, photosynthesis will also strengthen accordingly. When light intensity is low and carbon dioxide concentration is low, raising the temperature is instead unfavorable to orchid growth. Therefore, when cultivating orchids in a greenhouse, heating equipment should be equipped with lighting equipment to achieve good results. At night or on rainy days, the temperature in the orchid room should be appropriately lowered to increase the temperature difference and promote the accumulation of dry matter. 4. Water: Water is a raw material of photosynthesis, but of the water absorbed by orchids, very little, less than 1%, is used for photosynthesis, while most of the water is used in other physiological processes and lost through transpiration. Therefore, the influence of water on photosynthesis is not direct; it mainly affects other physiological activities, thereby indirectly affecting photosynthesis. When the water metabolism of orchids is disrupted, the water in the leaves decreases, causing the stomata to close and preventing the entry of carbon dioxide, thereby also affecting the photosynthesis of orchids. 5. Nutrient elements: Nutrient elements also have a certain influence on orchid photosynthesis. Magnesium and nitrogen are components of chlorophyll; iron and manganese participate in the formation of chlorophyll; boron, potassium, phosphorus, etc. can promote the transport and transformation of organic matter. Therefore, rational fertilization plays a very important role in the smooth progress of orchid photosynthesis. (Xinyuanxuan) CultivationWhen cultivating orchids, the method of carbon dioxide fertilization can be applied to increase the carbon dioxide content in the air. (I have not tested this myself, so I do not know how effective it is; I hope orchid growers who have used it can give a detailed introduction.) In addition, fermentation of organic matter can also increase the indoor carbon dioxide concentration. However, when the carbon dioxide concentration in the air is too high, it is also unfavorable to orchid photosynthesis. When the concentration exceeds 1%, it will cause poisoning of the orchid protoplasm, and the stomata will close, thereby inhibiting photosynthesis. At this time, if the light intensity is increased, the usable concentration of carbon dioxide can be relatively raised. Therefore, ventilation, exhaust, and supplemental lighting equipment should be installed in the orchid room. 3. Temperature: Under normal circumstances, orchids can carry out photosynthesis normally at 5~36 degrees, and the most suitable temperature is 15~30 degrees. Below 5 degrees, photosynthesis is inhibited. Starting from the lower temperature limit, photosynthesis strengthens as the temperature rises, but when it exceeds 36 degrees, photosynthesis will become very weak or even stop. The effect of temperature on orchid photosynthesis is directly related to light intensity and carbon dioxide concentration. Within a certain range, under conditions of higher light intensity and higher carbon dioxide concentration, photosynthesis will also strengthen accordingly. When light intensity is low and carbon dioxide concentration is low, raising the temperature is instead unfavorable to orchid growth. Therefore, in the greenhouseCultivationWhen cultivating orchids, heating equipment should be equipped with supplemental lighting equipment to achieve good results. At night or on cloudy and rainy days, the temperature in the orchid room should be appropriately lowered to increase the temperature difference and promote dry matter accumulation. 4. Water: Water is a raw material for photosynthesis, but of the water absorbed by orchids, very little less than 1% is used for photosynthesis, while most of the water is used in other physiological processes and lost through transpiration. Therefore, the effect of water on photosynthesis is not direct; it mainly affects other physiological activities, thereby indirectly affecting photosynthesis. When the water metabolism of orchids is disrupted, the water in the leaves decreases, causing the stomata to close and preventing carbon dioxide from entering, thus also affecting orchid photosynthesis. 5. Nutrient elements: Nutrient elements also have a certain effect on orchid photosynthesis. Magnesium and nitrogen are components of chlorophyll; iron and manganese participate in the process of chlorophyll formation; boron, potassium, phosphorus, etc. can promote the transport and transformation of organic matter. Therefore, rational fertilization plays a very important role in the smooth progress of orchid photosynthesis. (Xinyuanxuan)