Due to the relatively closed environment of greenhouse vegetables, especially in winter and spring, the ventilation is reduced, resulting in a serious shortage of co2 content in the greenhouse, which reduces the photosynthetic efficiency of vegetables and reduces the photosynthetic products, resulting in low yield of greenhouse vegetables. Poor quality. The addition of co2 gas fertilizer in the greenhouse can increase the chlorophyll content, make the plant grow robust, increase vegetable yield and improve product quality.
There are many ways to increase the concentration of co2 in the air in the greenhouse by fertilization methods, such as the use of liquid CO2 release method in steel cylinders, combustion of coal or other hydrocarbons to produce co2, and the implementation of intercropping or development of vegetables and edible fungi. Bioecological law. However, these methods are also generating harmful gases at the same time as co2 is produced, or the cost is high and the operation is inconvenient, which is not ideal. At present, the more commonly used methods for adding co2 are chemical reaction method and soil fertilization method.
1. Chemical reaction method A method in which a chemical reaction of sulfuric acid and ammonium hydrogencarbonate is used to form co2, and a by-product ammonium sulfate can be used as a fertilizer. Generally, for every 667 square meters of greenhouse, 3 kg to 4 kg of ammonium bicarbonate is used every day, and 96% of concentrated sulfuric acid is added from 2 kg to 2.5 kg, so that the concentration of co2 in the greenhouse can reach 1000 ppm. For specific operation, a commercially available co2 generator or a small plastic bucket can be used. Concentrated sulfuric acid should be diluted with water by 1:3 before use. When diluted, concentrate concentrated sulfuric acid into water. Do not pour water into concentrated sulfuric acid. Each greenhouse is equipped with 6 to 10 points of co2, and the barrel is evenly suspended in the greenhouse. The height of the barrel is slightly higher than the height of the vegetable growth point, so that the co2 is uniformly diffused and absorbed by the vegetables. In the chemical reaction, the plastic barrel may be first placed with ammonium bicarbonate, and then the diluted sulfuric acid may be injected; or the diluted sulfuric acid may be first placed in the barrel, and then the desired ammonium hydrogencarbonate is added. In short, the sulfuric acid reaction should be completed until the addition of ammonium bicarbonate does not produce bubbles, so as to reduce the acidity of the waste liquid, and use the waste liquid for 50 times or more of the water for top dressing.
2. The soil fertilization method applies the various fertilizers that can produce co2 to the soil, and the co2 which is slowly released by the decomposition is continuously replenished in the greenhouse to supply the growth and development of the vegetables. Commonly used soil fertilization methods include: (1) adding organic fertilizer method. Using various organic fertilizers to be applied to the soil and decomposing in the soil to produce co2; (2) deep application of ammonium bicarbonate. In the vegetable line, ammonium bicarbonate is buried in the soil layer of 8 cm to 15 cm per square meter in 8 cm to 10 cm, 2 times to 3 times per month, and the co2 concentration in the greenhouse is increased by the co2 produced by its natural decomposition. (3) Solid co2 granular fertilizer method. The commercially available spherical solid co2 granular fertilizer is applied to the soil by means of ditch application, acupoint application, etc., and the co2 is slowly released, and is applied once every 30 days to 40 days. This method has obvious effects and is safe to use.
Types and hazards of harmful gases in plastic greenhouses 1. The two gases, ammonia and nitrous acid, are mainly derived from nitrogen fertilizers and organic fertilizers applied to the soil, especially in the case of excessive fertilization and soil drought. High temperature will decompose and produce a large amount of ammonia in the short term (usually 3 days to 4 days after fertilization). When the concentration of ammonia exceeds 5ppm, some sensitive vegetables, such as cucumbers and tomatoes, will be harmed. The original leaves will be browned when they are boiled. When the concentration of ammonia reaches 4%, the seedlings of vegetables will be treated for 24 hours. Will die. When the content of nitrous acid gas in the air reaches 2ppm to 3ppm, it will cause damage to sensitive vegetables such as eggplant, tomato, pepper, etc. The symptoms mainly occur on the leaves close to the ground, rarely harming the new leaves, and it is also like being boiled by boiling water. Similarly, due to the acidification of nitrous acid, the veins gradually turn white. In severe cases, only the veins are left, and the mesophyll is bleached and died; this occurs mostly in 10 days to 15 days after fertilization. The easiest and most common method for testing the excess of ammonia and nitrous acid in plastic greenhouses is to determine the pH of the water droplets dripping from the top of the greenhouse, ie the pH. Under normal circumstances, the ph value of water droplets is 7.0 to 7.2, that is, neutral or slightly alkaline. If the water droplets are alkaline, the ammonia is excessive; if the water droplets are acidic, the nitrous acid gas is too much. If the pH is below 5.5, it will cause harm.
2. When carbon monoxide and sulfur dioxide gas plastic greenhouses are heated by coal fire, a large amount of carbon monoxide and sulfur dioxide gas are often generated due to incomplete combustion or unclear flue. The hazards of these two gases can be divided into three types: one is recessive poisoning, the vegetable itself has no obvious visible symptoms, but the assimilation function is reduced, the quality is worse, generally has little effect on the yield; the second is chronic poisoning, gas Intrusion from the stomata on the back of the blade, brown spots appear on the stomata and its surroundings, the surface is yellowed; the third is acute poisoning, which produces whitening symptoms similar to those of nitrous acid gas.
3. Toxic gases emitted by plastic film itself Some plastic films will produce some volatile substances during use. These substances can invade the inside of plants through pores or water holes in the leaves, destroying cell tissues and chloroplasts, and significantly reducing photosynthesis. , seriously affecting the yield and quality of vegetables. It has been shown that when the amount of 2-2-isobutyl phthalate dissolved in the water droplets of the greenhouse reaches 10 ppm to 30 ppm, the water droplets will be seriously poisoned after being atomized or absorbed by the roots and leaves through the vegetables; The concentration of chlorine in the air reaches 0.1ppm. When exposed to 2 hours, the radish can be harmed to a concentration of 0.5ppm to 0.8ppm. Only 4 hours of exposure can cause most vegetables to be damaged. Initially, white veins appear between the veins. Light brown irregular spot or blocky lesions, when the whole leaves become white or even fall off in severe cases; when the concentration of ethylene gas in the protected area reaches 1ppm or more, the leaf margin and veins of the vegetables can be yellowed and then whitened until Withered.
In addition, when the smoked pesticides in the greenhouse are excessive, the vegetables will also cause harm to the vegetables. For example, excessive use of chlorothalonil fuming agents will cause the leaves and edge tissues of the vegetables to die and die, especially under high temperature and high humidity conditions. The victim is more serious.
Fertilization period and time greenhouse vegetables have different fertilization effects at different growth stages. Increasing the application of co2 at the seedling stage can shorten the seedling age, accelerate the development, promote the differentiation of flower buds, and facilitate the cultivation of strong seedlings; do not apply co2 before planting until the seedlings are slowed down, and control the amount of co2 when applying the seedlings to prevent the plants from growing long; fruit and vegetables are fruit and The fruit expansion period is the best period for adding co2, and the fertilization should last for one month, and it cannot be stopped in the middle to avoid premature senescence of the plants.
The daily application time should be based on the daily variation of the co2 concentration in the greenhouse. Co2 was applied half an hour after the morning exposure; the sun was continuously applied for more than 2 hours and maintained at a higher concentration until one hour before ventilation; the rainy weather should stop being applied.
Precautions for fertilization 1. Since co2 is heavier than air, in order to uniformly apply the added co2 to the functional leaves of the crop, the co2 generating device should be placed at the height of the canopy of the plant population, and multiple points should be applied to ensure its uniformity. So that the added co2 is fully and effectively utilized.
2, long-term high concentration of application of co2 will have harmful effects on vegetables, such as aging plants, leaf roll, chlorophyll decline. Therefore, the use concentration should be slightly lower than the optimum concentration, the number of applications should be appropriately reduced, and the management of fertilizer and water should be strengthened.
3. During the application of co2, the shed should be kept relatively closed to prevent the co2 gas from escaping outside the shed to improve the utilization of co2 and reduce the production cost.
The concentration of co2 in the air of fertilization concentration is generally about 300ppm. However, when the concentration of co2 in vegetable crops is below 600ppm～1500ppm, the photosynthetic rate is the fastest. Among them, the concentration of co2 in fruit and vegetable is 1000ppm～1500ppm, and that of leafy vegetables is 1000ppm.
Symptoms and remedial measures of lack of carbon dioxide in vegetables 1. Symptoms of lack of carbon dioxide in greenhouse vegetables: 1 vegetables with sufficient carbon dioxide, strong plant growth, high chlorophyll content, dark green and lustrous leaves, vegetables lacking carbon dioxide, dark and dull leaves, plants The potential is poor. 2The vegetables with sufficient carbon dioxide bloom early, and there are many female flowers.
The flowers and fruits are less shed, and the vegetables lacking carbon dioxide bloom late, the female flowers are less, and the flowers and fruits are more shed. 3 The vegetables with sufficient carbon dioxide are strong on the leaves, and the leaves lacking carbon dioxide are flat, perpendicular or drooping with the main branches, spots appear on the leaves, or uneven, or yellow and rot. In addition, if one or two vegetables close to the vents grow stronger, the results are more, the fruits are well developed, and the vegetables far from the vents are growing poorly, the flowers and fruits are more shed, the fruit is rare, and the delay is not long. An important basis for carbon dioxide.
2, remedial measures: There are two main types, one is to strengthen ventilation and ventilation, to promote gas exchange inside and outside the shed; the second is to carry out carbon dioxide fertilization. Carbon dioxide fertilization is a new technology that has a significant effect on increasing the yield of vegetable protection and cultivation. The yield increase is generally around 30%, especially for the winter production of winter-heated greenhouses and the early spring production of spring-type greenhouses. . The best time for carbon dioxide fertilization is generally 9 hours after sunrise, from November to January, 8 hours from late January to late February, and 6:30 to 7:00 from March to April; The application period is best when the fruit is rapidly inflated. The application concentration is generally about 1000ppm; in winter, the greenhouse cucumber is 1300ppm～1700ppm in seedling stage and 1500ppm～2000ppm in fruit setting. The amount of application exceeds the damage of the leaves and the occurrence of focal edges, which is not conducive to photosynthesis and harmful to human health. In addition, in greenhouses where carbon dioxide is applied, the temperature during the day should be increased by 3 °C to 4 °C, and the temperature fluctuation at night should be slightly increased. It is slightly higher in the first half of the night and slightly lower in the lower half of the night to improve the fertilization effect.
How to avoid the harmful gases in the greenhouse, not only affect the growth and development of vegetables, but also directly endanger the health of the vegetable farmers. Therefore, we must actively take measures to prevent and cure.
l, scientific fertilization of greenhouse vegetable fertilization, should be based on high-quality soil and fertilizer, appropriate application of phosphorus, potassium fertilizer, as little as possible application of nitrogen fertilizer, no application of cake fertilizer and human waste, and adhere to the base fertilizer, supplemented by topdressing. Topdressing should be strictly in accordance with the principle of “small number of times†to prevent excessive fertilization; generally, when urea is applied, it should not exceed 0.6 kg per 10 square meters. The method of top dressing is to apply deep ditching, and then apply the soil tightly, and timely watering to dilute the fertilizer.
2. Timely ventilation and ventilation. When the temperature is high at noon, open the vents to circulate the air; even on cloudy or snowy days, perform a short ventilation at noon to reduce the harmful gases in the shed as much as possible. , reduce the humidity of the air.
3, reduce the toxic gas source plastic greenhouse when using coal fire to warm, try to make the fuel fully burned, and install a chimney on the stove, the harmful gas is exported out of the shed.
4. Use non-toxic plastic film instead of plastic film with more plasticizer as the film.
5, remedial measures found that greenhouse vegetables suffer from sulfur dioxide damage, timely spraying barium carbonate, lime water, stone sulfur mixture or 0.5% synthetic detergent solution; cucumber suffers from ammonia hazard, spraying 1% vinegar solution on the opposite side of the leaf, both Has a significant effect.
There are many ways to increase the concentration of co2 in the air in the greenhouse by fertilization methods, such as the use of liquid CO2 release method in steel cylinders, combustion of coal or other hydrocarbons to produce co2, and the implementation of intercropping or development of vegetables and edible fungi. Bioecological law. However, these methods are also generating harmful gases at the same time as co2 is produced, or the cost is high and the operation is inconvenient, which is not ideal. At present, the more commonly used methods for adding co2 are chemical reaction method and soil fertilization method.
1. Chemical reaction method A method in which a chemical reaction of sulfuric acid and ammonium hydrogencarbonate is used to form co2, and a by-product ammonium sulfate can be used as a fertilizer. Generally, for every 667 square meters of greenhouse, 3 kg to 4 kg of ammonium bicarbonate is used every day, and 96% of concentrated sulfuric acid is added from 2 kg to 2.5 kg, so that the concentration of co2 in the greenhouse can reach 1000 ppm. For specific operation, a commercially available co2 generator or a small plastic bucket can be used. Concentrated sulfuric acid should be diluted with water by 1:3 before use. When diluted, concentrate concentrated sulfuric acid into water. Do not pour water into concentrated sulfuric acid. Each greenhouse is equipped with 6 to 10 points of co2, and the barrel is evenly suspended in the greenhouse. The height of the barrel is slightly higher than the height of the vegetable growth point, so that the co2 is uniformly diffused and absorbed by the vegetables. In the chemical reaction, the plastic barrel may be first placed with ammonium bicarbonate, and then the diluted sulfuric acid may be injected; or the diluted sulfuric acid may be first placed in the barrel, and then the desired ammonium hydrogencarbonate is added. In short, the sulfuric acid reaction should be completed until the addition of ammonium bicarbonate does not produce bubbles, so as to reduce the acidity of the waste liquid, and use the waste liquid for 50 times or more of the water for top dressing.
2. The soil fertilization method applies the various fertilizers that can produce co2 to the soil, and the co2 which is slowly released by the decomposition is continuously replenished in the greenhouse to supply the growth and development of the vegetables. Commonly used soil fertilization methods include: (1) adding organic fertilizer method. Using various organic fertilizers to be applied to the soil and decomposing in the soil to produce co2; (2) deep application of ammonium bicarbonate. In the vegetable line, ammonium bicarbonate is buried in the soil layer of 8 cm to 15 cm per square meter in 8 cm to 10 cm, 2 times to 3 times per month, and the co2 concentration in the greenhouse is increased by the co2 produced by its natural decomposition. (3) Solid co2 granular fertilizer method. The commercially available spherical solid co2 granular fertilizer is applied to the soil by means of ditch application, acupoint application, etc., and the co2 is slowly released, and is applied once every 30 days to 40 days. This method has obvious effects and is safe to use.
Types and hazards of harmful gases in plastic greenhouses 1. The two gases, ammonia and nitrous acid, are mainly derived from nitrogen fertilizers and organic fertilizers applied to the soil, especially in the case of excessive fertilization and soil drought. High temperature will decompose and produce a large amount of ammonia in the short term (usually 3 days to 4 days after fertilization). When the concentration of ammonia exceeds 5ppm, some sensitive vegetables, such as cucumbers and tomatoes, will be harmed. The original leaves will be browned when they are boiled. When the concentration of ammonia reaches 4%, the seedlings of vegetables will be treated for 24 hours. Will die. When the content of nitrous acid gas in the air reaches 2ppm to 3ppm, it will cause damage to sensitive vegetables such as eggplant, tomato, pepper, etc. The symptoms mainly occur on the leaves close to the ground, rarely harming the new leaves, and it is also like being boiled by boiling water. Similarly, due to the acidification of nitrous acid, the veins gradually turn white. In severe cases, only the veins are left, and the mesophyll is bleached and died; this occurs mostly in 10 days to 15 days after fertilization. The easiest and most common method for testing the excess of ammonia and nitrous acid in plastic greenhouses is to determine the pH of the water droplets dripping from the top of the greenhouse, ie the pH. Under normal circumstances, the ph value of water droplets is 7.0 to 7.2, that is, neutral or slightly alkaline. If the water droplets are alkaline, the ammonia is excessive; if the water droplets are acidic, the nitrous acid gas is too much. If the pH is below 5.5, it will cause harm.
2. When carbon monoxide and sulfur dioxide gas plastic greenhouses are heated by coal fire, a large amount of carbon monoxide and sulfur dioxide gas are often generated due to incomplete combustion or unclear flue. The hazards of these two gases can be divided into three types: one is recessive poisoning, the vegetable itself has no obvious visible symptoms, but the assimilation function is reduced, the quality is worse, generally has little effect on the yield; the second is chronic poisoning, gas Intrusion from the stomata on the back of the blade, brown spots appear on the stomata and its surroundings, the surface is yellowed; the third is acute poisoning, which produces whitening symptoms similar to those of nitrous acid gas.
3. Toxic gases emitted by plastic film itself Some plastic films will produce some volatile substances during use. These substances can invade the inside of plants through pores or water holes in the leaves, destroying cell tissues and chloroplasts, and significantly reducing photosynthesis. , seriously affecting the yield and quality of vegetables. It has been shown that when the amount of 2-2-isobutyl phthalate dissolved in the water droplets of the greenhouse reaches 10 ppm to 30 ppm, the water droplets will be seriously poisoned after being atomized or absorbed by the roots and leaves through the vegetables; The concentration of chlorine in the air reaches 0.1ppm. When exposed to 2 hours, the radish can be harmed to a concentration of 0.5ppm to 0.8ppm. Only 4 hours of exposure can cause most vegetables to be damaged. Initially, white veins appear between the veins. Light brown irregular spot or blocky lesions, when the whole leaves become white or even fall off in severe cases; when the concentration of ethylene gas in the protected area reaches 1ppm or more, the leaf margin and veins of the vegetables can be yellowed and then whitened until Withered.
In addition, when the smoked pesticides in the greenhouse are excessive, the vegetables will also cause harm to the vegetables. For example, excessive use of chlorothalonil fuming agents will cause the leaves and edge tissues of the vegetables to die and die, especially under high temperature and high humidity conditions. The victim is more serious.
Fertilization period and time greenhouse vegetables have different fertilization effects at different growth stages. Increasing the application of co2 at the seedling stage can shorten the seedling age, accelerate the development, promote the differentiation of flower buds, and facilitate the cultivation of strong seedlings; do not apply co2 before planting until the seedlings are slowed down, and control the amount of co2 when applying the seedlings to prevent the plants from growing long; fruit and vegetables are fruit and The fruit expansion period is the best period for adding co2, and the fertilization should last for one month, and it cannot be stopped in the middle to avoid premature senescence of the plants.
The daily application time should be based on the daily variation of the co2 concentration in the greenhouse. Co2 was applied half an hour after the morning exposure; the sun was continuously applied for more than 2 hours and maintained at a higher concentration until one hour before ventilation; the rainy weather should stop being applied.
Precautions for fertilization 1. Since co2 is heavier than air, in order to uniformly apply the added co2 to the functional leaves of the crop, the co2 generating device should be placed at the height of the canopy of the plant population, and multiple points should be applied to ensure its uniformity. So that the added co2 is fully and effectively utilized.
2, long-term high concentration of application of co2 will have harmful effects on vegetables, such as aging plants, leaf roll, chlorophyll decline. Therefore, the use concentration should be slightly lower than the optimum concentration, the number of applications should be appropriately reduced, and the management of fertilizer and water should be strengthened.
3. During the application of co2, the shed should be kept relatively closed to prevent the co2 gas from escaping outside the shed to improve the utilization of co2 and reduce the production cost.
The concentration of co2 in the air of fertilization concentration is generally about 300ppm. However, when the concentration of co2 in vegetable crops is below 600ppm～1500ppm, the photosynthetic rate is the fastest. Among them, the concentration of co2 in fruit and vegetable is 1000ppm～1500ppm, and that of leafy vegetables is 1000ppm.
Symptoms and remedial measures of lack of carbon dioxide in vegetables 1. Symptoms of lack of carbon dioxide in greenhouse vegetables: 1 vegetables with sufficient carbon dioxide, strong plant growth, high chlorophyll content, dark green and lustrous leaves, vegetables lacking carbon dioxide, dark and dull leaves, plants The potential is poor. 2The vegetables with sufficient carbon dioxide bloom early, and there are many female flowers.
The flowers and fruits are less shed, and the vegetables lacking carbon dioxide bloom late, the female flowers are less, and the flowers and fruits are more shed. 3 The vegetables with sufficient carbon dioxide are strong on the leaves, and the leaves lacking carbon dioxide are flat, perpendicular or drooping with the main branches, spots appear on the leaves, or uneven, or yellow and rot. In addition, if one or two vegetables close to the vents grow stronger, the results are more, the fruits are well developed, and the vegetables far from the vents are growing poorly, the flowers and fruits are more shed, the fruit is rare, and the delay is not long. An important basis for carbon dioxide.
2, remedial measures: There are two main types, one is to strengthen ventilation and ventilation, to promote gas exchange inside and outside the shed; the second is to carry out carbon dioxide fertilization. Carbon dioxide fertilization is a new technology that has a significant effect on increasing the yield of vegetable protection and cultivation. The yield increase is generally around 30%, especially for the winter production of winter-heated greenhouses and the early spring production of spring-type greenhouses. . The best time for carbon dioxide fertilization is generally 9 hours after sunrise, from November to January, 8 hours from late January to late February, and 6:30 to 7:00 from March to April; The application period is best when the fruit is rapidly inflated. The application concentration is generally about 1000ppm; in winter, the greenhouse cucumber is 1300ppm～1700ppm in seedling stage and 1500ppm～2000ppm in fruit setting. The amount of application exceeds the damage of the leaves and the occurrence of focal edges, which is not conducive to photosynthesis and harmful to human health. In addition, in greenhouses where carbon dioxide is applied, the temperature during the day should be increased by 3 °C to 4 °C, and the temperature fluctuation at night should be slightly increased. It is slightly higher in the first half of the night and slightly lower in the lower half of the night to improve the fertilization effect.
How to avoid the harmful gases in the greenhouse, not only affect the growth and development of vegetables, but also directly endanger the health of the vegetable farmers. Therefore, we must actively take measures to prevent and cure.
l, scientific fertilization of greenhouse vegetable fertilization, should be based on high-quality soil and fertilizer, appropriate application of phosphorus, potassium fertilizer, as little as possible application of nitrogen fertilizer, no application of cake fertilizer and human waste, and adhere to the base fertilizer, supplemented by topdressing. Topdressing should be strictly in accordance with the principle of “small number of times†to prevent excessive fertilization; generally, when urea is applied, it should not exceed 0.6 kg per 10 square meters. The method of top dressing is to apply deep ditching, and then apply the soil tightly, and timely watering to dilute the fertilizer.
2. Timely ventilation and ventilation. When the temperature is high at noon, open the vents to circulate the air; even on cloudy or snowy days, perform a short ventilation at noon to reduce the harmful gases in the shed as much as possible. , reduce the humidity of the air.
3, reduce the toxic gas source plastic greenhouse when using coal fire to warm, try to make the fuel fully burned, and install a chimney on the stove, the harmful gas is exported out of the shed.
4. Use non-toxic plastic film instead of plastic film with more plasticizer as the film.
5, remedial measures found that greenhouse vegetables suffer from sulfur dioxide damage, timely spraying barium carbonate, lime water, stone sulfur mixture or 0.5% synthetic detergent solution; cucumber suffers from ammonia hazard, spraying 1% vinegar solution on the opposite side of the leaf, both Has a significant effect.
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