The proposed ventilation methods are as follows: 1 leaf, 1-core stage, small ventilation, the temperature in the greenhouse is not higher than 28 ℃; 2 leaves and 1-core stage, the temperature in the greenhouse is not more than 25 ℃; after the three leaf one heart stage, the film on both ends of the shed is uncovered, and the shed end should be made with protective skirt, and the temperature in the shed is about 23 ℃;
after the 3-leaf stage, the criterion of "better cold than hot" should be followed, and the shed can not be closed when the temperature is about 10 ℃. In sunny days, ventilation should be carried out in the morning, and the shed should be closed before 4:00 p.m. if ventilation is carried out only when the temperature is high at noon, the seedlings will be hot or cold suddenly, which is easy to cause bacterial wilt. The vent should be changed with the change of leaf age, and the position of the vent should be replaced, so as to avoid the dwarf of grass seedlings near the tuyere due to low temperature caused by long-term ventilation.
The principle of greenhouse ventilation should be from 5:00 a.m. to 5:30 a.m., "as soon as the sun comes out, open the small mouth first, then the big mouth", "first the reverse side, then the front side", "clear day, rainy day also need to pass" and so on.
