In the greenhouse vegetable cultivation process, because of closed facilities, there is little exchange of air inside and outside, and harmful gases such as ammonia, nitrous acid gas, carbon monoxide, sulfur dioxide, and chlorine are not emitted, which can harm the growth and development of vegetables. Production management should pay attention to prevention.
First, the cause of harmful gases
1. Ammonia. Mainly comes from the decomposition of available nitrogen fertilizers in the soil, such as urea, diammonium phosphate, ammonium bicarbonate, ammonium sulfate, etc. These fertilizers will decompose and evaporate when they encounter high temperature environment and produce ammonia, especially in the shed. Fertilization method (point application, applicator) topdressing this type of fertilizer can easily cause ammonia to evaporate and increase the content of ammonia in the air. Ammonia also comes from uncontaminated manure in the soil, such as chicken manure, pig manure, cow manure, and cake manure. These fertilizers will also release ammonia if they are decomposed and fermented by microorganisms after being applied to the soil without being fully decomposed.
2. Nitrite gas. It mainly comes from the nitrification reaction of nitrogenous fertilizer in the soil. After the nitrogen fertilizer is applied to the soil, nitrite gas is produced by the nitrification of microorganisms. If you use too much available nitrogen fertilizer in the greenhouse, it is easy to produce nitrous acid gas.
3. Chlorine. Mainly from toxic plastic film or toxic plastic pipe.
4. Carbon monoxide, sulfur dioxide. It is derived from the burning of coal or firewood when heated and heated in a greenhouse.
Second, harmful gas hazards
1. Ammonia. Ammonia hazards appear more than 3 to 4 days after dressing. When the concentration of ammonia in the air reaches 5 ml/l, the crop will be harmed. The first victim is the leaf margin and part of the heart leaf of the vigorously vitalized leaves. The leaf margin tissue first turns brown and then becomes white, and when it is severe, it will die. . If the ammonia concentration reaches 40 ml/l, the crop will be more seriously harmed, even killing the whole plant. Cucumbers, tomatoes, peppers, etc. are more sensitive to ammonia reactions, and eggplants are less responsive.
2. Nitrite gas. Most of the harm symptoms occur 10 to 15 days after fertilization. When the concentration of nitrous acid in the air reaches 2 ml/l, the crop will be harmed. If white spots appear on the leaves, the veins will turn white. Tomato, eggplant, cucumber, celery, lettuce, etc. are more sensitive to nitrous acid gas.
3. Chlorine. Chlorine gas enters the mesophyll tissue through the stomata of the leaf of the crop, destroying the chlorophyll and mesophyll tissues. At the beginning, the leaf margins turn white and dry, and the entire leaf dies when severe.
4. Carbon monoxide and sulfur dioxide. Both plants can have white or brown spots on the front and back of the leaves, and those with heavy leaves can die.
Third, preventive measures
1. Pay attention to ventilation. As long as the temperature is not very low, open the tuyere every day, ventilation for at least 50 minutes. Because the “ammonia†and “nitrification†reactions of soil and fertilizers always release ammonia gas and nitrous acid gas, they must be ventilated to avoid excessive levels and damage crops. Ventilation is best in the early morning or at night, and it can simultaneously discharge the indoor steam, reduce the air humidity in the facility, and help prevent and control the occurrence of diseases. If the outdoor temperature is too low, ventilation will cause a rapid decline in indoor temperature, ventilation should be properly reduced, but no ventilation is allowed, can be a once every 2 days, change the morning and night ventilation for afternoon ventilation, time can be less than 30 minutes. Every morning, test the dew on the shed film with a pH test paper. If it is alkaline, it indicates that ammonia gas is produced and the air must be released promptly.
2. Scientific fertilization. Before organic fertilizers are applied to the sheds for 2 to 3 months, they must be added with water and wetted. After the accumulation, the plastic film is tightly sealed and fully fermented and decomposed before being applied to the shed.
Chemical fertilizers are forbidden to use nitrogen fertilizers, such as urea, ammonium bicarbonate, ammonium sulfate and diammonium fertilizers, in the facilities. If these fertilizers are applied to the soil, they cannot be dissolved and absorbed by the soil solution in time. Hazardous crops. Therefore, the use should be reduced as much as possible. If topdressing must be applied, it should be combined with watering. Fertilizer should be dissolved into an aqueous solution in advance, flushed with water to prevent evaporation of ammonia and harm the vegetables.
3. Pay attention to the film quality. Can choose to use polyethylene plastic film or reliable PVC plastic film, not only can prevent harmful gas dissolved in water droplets harm vegetables, but also reduce the disease.
4. Safe heating. Furnace and flue design should be reasonable, installation must be closed, and high-quality low-sulfur coal should be used for fuel. Strengthen heat management to prevent smoking. When the indoor ignition warms up, it must be fully fired with open flame, and the burning time must be strictly controlled to prevent harmful gases such as carbon monoxide and sulfur dioxide from exceeding the standards and endangering crops.
5. symptomatic rescue. When there are signs of poisoning, the cause should be identified. In addition to taking targeted measures, measures such as watering, fertilizing, loosening soil, etc. should be taken to promote the rapid recovery of the affected plants.
Our medicinal synthetic polyisoprene gasket for injection does not contain any substances that can easily produce pyrogen. We now use a unique technique to add cytotoxicity to the routine test of butyl rubber stoppers such as pyrogen, hemolysis, acute systemic toxicity test and so on. Systemic injection test and intradermal stimulation test have been used abroad for many years.Our good puncture resistance ensures the minimum rate of chip drop during the puncture process and our good self-sealing performance can guarantee no leakage during using process in hospital.Also,good retention of puncture device ensures that there is no needle slider and needle drop in the process of hospital use.
Isoprene Gasket,Medical Synthetic Isoprene Gasket,Pharmaceutical Polyisoprene Disc,Pharmaceutical Synthetic Disc
SUZHOU CRH PHARMACEUTICAL TECHNOLOGY CO.,LTD , https://www.crh-health.com