I. Harm and Prevention of Harm
Gas disasters often cause damage to vegetables in a short period of time, resulting in a significant reduction in the production of vegetables and a decline in quality.
1. Ammonia. In greenhouses, fertilizers such as organic fertilizers such as chicken manure, human waste, and cake fertilizers, and urea, etc., which are not fully cooked, can be fermented and decomposed under high temperature for 3 to 4 days to produce large amounts of ammonia, and ammonia gas invades through the pores of the leaves. The affected parts were mainly leaves, which showed flooding at the victim's site. The leaf color became lighter, whiter, or lavender, and the leaf margins were burning. In severe cases, the plants could die. Cucumbers, tomatoes, peppers, and celery are the most sensitive to ammonia and suffer the most.
2. Nitrite gas. Once a large amount of organic fertilizer and ammonium nitrate is applied in the greenhouse, a large amount of nitrous acid gas is emitted from the soil during the conversion from alkaline to acidic in the soil. The leaves of the affected vegetables were immersed in water with irregular chlorophyll or brown spots. In severe cases, the leaf segments turned white and withered; when the concentration reached 10 mg/kg, the veins also turned white and died. Vegetables such as tomato, eggplant, lettuce, and pepper are more sensitive to nitrous gases.
Preventive measures: First, rational fertilization, shed indoor not a large number of disposable chicken manure, cake fertilizer, human waste and other organic fertilizers and urea, diammonium phosphate and other fertilizers, can use the enzyme composting compost or full Decomposed organic fertilizers adopt formula fertilization to reduce the use of chemical fertilizers. At the same time pay attention to the selection of a reasonable fertilization method, topdressing urea, diammonium phosphate and other fertilizers, should be buried and combined with watering, to avoid the volatilization of harmful gases. The second is ventilation, ventilation, greenhouse vegetable management, should pay attention to regular ventilation to reduce the accumulation of harmful gases within the shed. After the top dressing, the ventilation and ventilation should be strengthened when the temperature is high at noon.
Second, the harm and prevention of drafts
Draughts are the rapid convection of cold air caused by the close of the winter greenhouse or the opening of the air outlet. This kind of wind has a great influence on the growth of vegetables. After a cold wind rushed over, the vegetables grew poorly, while the leaves wilted and fell.
The most effective measure for preventing cross-winds is to install a windshield at the door and the air outlet to cushion the drafts against the vegetables. Especially at the doorway, in addition to setting the windshield film, the shed door is best to hang the cotton curtain, which is both heat-insulating and wind-blocking, which can effectively block the entrance of the draft wind. For vegetables that are harmed by drafts, they should be promptly sprayed with foliar fertilizer or plant growth regulators to promote their recovery as soon as possible.
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