Ventilation and ventilation are required during the growth of greenhouse vegetables in order to adjust the temperature, humidity, carbon dioxide concentration and harmful gases in the greenhouse. When farmers are ventilating, apply appropriate techniques to minimize the effects of ventilation on the growth of vegetables. 1. Temperature requirements. According to the temperature requirements of the growth and development of the vegetables grown in the greenhouse, it is generally necessary to perform ventilation and ventilation when the temperature in the greenhouse is higher than the temperature at which the vegetables are grown to prevent the occurrence of chilling or freezing damage. 2. Air volume requirements. Ventilation and ventilation of the shed keeps the principle of small to large and windy to the wind. Pay attention to adjust the local temperature difference inside the shed, relatively early ventilation at high temperature, put a large air outlet; relatively late at low temperature, put a small air outlet. At the same time, prevent cold wind from directly blowing to vegetable plants, causing freezing damage to vegetable leaves and young fruits. Close the air vents should be carried out from large to small, from more to less. 3. Time requirements. The purpose of ventilation and ventilation is to cool down the water and replenish carbon dioxide. The time is generally controlled when the temperature in the greenhouse is too high, the relative humidity is large, and the photosynthesis of vegetables is accelerated. It is usually ventilated 1 to 2 hours after the curtain is cleared on a sunny morning. In addition, after watering or fertilizing or spraying pesticides, it should also be ventilated for a short period of time; in the case of rainy weather, when the relative humidity in the shed is large, carbon dioxide is deficient and harmful gases are accumulated, small winds should also be put in a short time; When encountering a long period of yin and yin, carry out a small wind on the outer cover of the shed. Disclaimer: Some articles on this website are transferred from the Internet. If legal rights of third parties are involved, please inform this website. phone The frequency of the ultrasonic energy meter is 1 megahertz (1 million Hz / s), the direction is accurate, and the penetration is strong. Through the three major effects of sound waves (mechanical, warm, physical and chemical effects) on various parts of the human body, to achieve the role of massage relaxation. Ultrasound Treatment, Healthcare Ultrasound, Medical Ultrasound, Therapeutic Ultrasound Shenzhen Guangyang Zhongkang Technology Co., Ltd. , https://www.nirlighttherapy.com