Plastic greenhouses plant vegetables , often due to improper fertilization methods in the process of vegetable cultivation, neglecting greenhouse ventilation, causing excessive toxic gases in the shed, endangering vegetables, and often misdiagnosed as vegetable diseases, resulting in vegetables that are not harvested or even rejected.

First, the hazards of toxic gases in vegetables grown in greenhouses:

1. Nitrogen is applied to the process of vegetable planting, such as excessive urea, barium sulfate and other quick-acting fertilizers, or improper fertilization methods. For example, due to the application of unfertilized organic fertilizer, ammonia is decomposed under high temperature conditions in the greenhouse, which will cause damage to vegetables. Water-stained spots appear on the leaf margin tissue, and in severe cases, the whole leaf wilted and died. Often misdiagnosed as frost or other diseases, vegetables sensitive to ammonia are cucumber, tomato, zucchini and so on.

Excessive application of ammonium nitrogen fertilizer by nitrous acid gas will reduce the effect of certain bacteria and cause local acidity of the soil. When the PH value is less than 5, nitrous acid gas is produced, which can cause white spots on the leaves of vegetables, and the whole leaves become white and dead, often misdiagnosed as powdery mildew. Vegetables sensitive to nitrous acid gas are eggplant, cucumber, zucchini and celery. , peppers, etc.

3. Ethylene and chlorine If the quality of the agricultural film or mulch film in the greenhouse is poor, or there is residual film in the ground, it is exposed to sunlight, and it is easy to produce harmful gases such as ethylene and chlorine under high temperature conditions in the shed. When the concentration reaches a certain level, the leaf margin or vein of the vegetable can be yellowed, and then whitened. In severe cases, the whole plant is dead. Often misdiagnosed as bacterial angular leaf spot, the damage to cucumber is particularly serious.

In addition, heating in the winter heats up, if the fuel is not burned enough, it will produce toxic gas, and if the ventilation is not timely, the carbon dioxide will accumulate too much. Affect vegetable production.

Second, how to prevent toxic gases in greenhouses:

1. Rational fertilization of vegetables. The organic fertilizer applied in the greenhouse must be fermented and fermented, the fertilizer should be of high quality, and the urea should be mixed with the superphosphate. The base fertilizer should be applied 20 cm deep, and the depth of the fertilizer should be about 12 cm, and watered in time after application.

2, greenhouse ventilation. In sunny and warm weather, the greenhouse should be ventilated in combination with the temperature adjustment. The rain and snow weather should also be properly ventilated.

3. When constructing the greenhouse, use safe and non-toxic agricultural film and mulch film to remove the waste plastic products and their residues in the shed in time.