Winter and spring sheds are ventilated and have learning

The author has been engaged in the technical guidance of shed production for many years, and found that even farmers who have been engaged in shed production for many years often make mistakes in ventilation and ventilation techniques in greenhouses, causing unnecessary losses to producers. Therefore, it is necessary to discuss the knowledge of ventilation and ventilation in greenhouse vegetable cultivation with farmers' friends. In the winter and spring season, how to ventilate the greenhouses where vegetables are grown?

It must be clarified that the purpose of ventilation in the greenhouse is to regulate the temperature, humidity and carbon dioxide concentration in the shed and to discharge harmful gases. It is especially important to properly and properly control the ventilation and ventilation technology. In the actual production and operation process, farmers' friends should pay attention to the following principles and measures.

1. Temperature: When the greenhouse is ventilated, the temperature in the shed must be higher than the temperature suitable for the growth of specific vegetables, so as to avoid chilling or freezing damage to the vegetables due to low indoor temperature after the venting. Therefore, it is necessary to understand and master the temperature requirements of various stages of growth and development of various vegetables.

2. The amount of air released: When the greenhouse is ventilated, it must adhere to the principle of keeping the wind from small to large, from small to large. At the same time, we must also pay attention to adjust the local temperature difference in the shed, relatively early ventilation at high temperature, put a large air outlet; at low temperature, it should be relatively late to release the wind, put a small air outlet. When closing the air vent, it should be from big to small, and gradually progress from more to less. In addition, ventilation should be prevented from directly blowing into the vegetable plants in the shed, resulting in high and low temperature, causing freezing damage to vegetable leaves and young fruits.

3. Time requirements for ventilation and ventilation: The purpose of ventilation and ventilation is to drain and cool, and meet the demand for carbon dioxide in photosynthesis of vegetables in the greenhouse. Therefore, the ventilation and ventilation time should generally be carried out when the temperature in the shed is too high, the relative humidity is large, and the photosynthesis is accelerated. That is to say, the 1-2 hours after the clear curtain is cleared in the morning. In addition, after watering and fertilizing or spraying pesticides, due to increased humidity, ventilation should also be short-lived. In the snowy weather, when the indoor relative humidity is large, carbon dioxide is deficient and harmful gas accumulation, it should also be carried out for a short time to release the small wind to meet the demand for carbon dioxide in vegetables. In addition, it can also reduce nutrient consumption in plants and improve the cold resistance of plants. In the case of a long time of yin and yin, it is necessary to open the curtains on the outer cover of the shed, and the amount of air to be released should be small to prevent the light from being too strong, and the transpiration is intensified, causing the vegetables to lose water and wilting.

In short, in the winter and spring seasons, the knowledge of ventilation and ventilation of cultivated shed vegetables should be comprehensively applied, and experience should be accumulated. It is necessary to consult and communicate with agricultural technicians frequently.

(Kong Fanhong)