High temperature in greenhouses is the main cause of fertilizer damage

Recently, many vegetable farmers have encountered some problems after spraying or spraying fertilizer. After investigation, it has been found that whether it is the yellowing of the plant stem after the tomato application (Figure 1), the dry ear, or the spraying of foliar fertilizer Symptoms of chlorotic plaque (Figure 2) or suspected yellow leaf curl virus produced by the leaves actually produce fertilizer or phytotoxicity.

After analysis, it was found that the occurrence of phytotoxicity and fertilizer damage were inseparable from the environmental conditions in the greenhouse (at temperatures above 30°C) when spraying or spraying micro fertilizers. With the passage of spraying time, if the pesticide is applied after 3:00 PM, the symptoms of phytotoxicity in the greenhouse tomato will decrease as the temperature gradually decreases. If it is sprayed in the morning, the symptoms of drug injury will increase with the gradual increase of temperature. At the same time, the greater the humidity (above 85%), the greater the spread of liquid droplets attached to the leaves of the liquid, the faster the penetration, and the more serious the occurrence of phytotoxicity. If it is an agent containing heavy metal ions such as copper and manganese ions, the risk of young buds, young fruit and flower heads will be increased. Yellowing of growing points, long rust spots on young fruit, and withering of flower heads will occur.

Generally speaking, the application of 0.3% to 0.5% urea can promote the turning of green leaves, and the effect of absorbing and adding green to the leaves in the ventilation and ventilation environment of 18°C ​​to 28°C is obvious. However, in the high temperature environment above 30°C, the respiratory function of the plant cells is accelerated and the photosynthesis is relatively weakened. If the dose of the pesticide is further increased, the leaves will be burned or burned, resulting in dehydration and bleaching of the leaves.

The vegetable farmers are afraid that the herbicides in the wheat field will drift and they will not dare to let off the wind for a long time. This will cause the greenhouses to be exposed to the high temperature environment of the sheds for a long time. The nutrient absorption of the plants will be lower than the respiratory consumption, and the growth status will be weak. If the fertilizer is applied again, the boron and potassium fertilizers that are not easy to produce fertilizer will be sprayed. It will also speed up the breathing of the leaves, weaken the photosynthesis, and cause the symptoms of "flower buds" in the leaves.

Summarizing these phenomena, it is not difficult to find that one common reason is "high temperature." To solve this problem, on the one hand, reduce the temperature of the greenhouse, properly water the plant, maintain the temperature required for normal growth of the plant during the day by 24°C to 28°C, and increase the air outlet or add a shade net. On the other hand, it is required to spray pesticides and fertilizers as early as possible in the evening or early morning. For the phytotoxicity and fertilizer damage already caused by high temperature, you can spray Bihu 4000 to 5000 times to relieve symptoms, or spray foliar fertilizers such as chloroplasts, ancient rice leaves, and Ruipei green, to promote the leaf spot Turn green.

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