How to manage the temperature, humidity and light after tomato planting in greenhouse in early spring?

(1) Temperature Management Greenhouse and other facilities are usually used for early-maturing cultivation of spring tomatoes, but the microclimate in the greenhouse in spring is characterized by large temperature changes; The temperature in the shed varies with the temperature outside. Due to the thermal insulation effect of agricultural film, the temperature in the shed can reach 38℃ on sunny days, and the highest temperature in the shed can reach 50℃ after the weather turns fine. In production, ventilation and cooling are neglected before and after the Spring Festival, and the phenomenon of burning seedlings or affecting the fruit of the first inflorescence often occurs. Therefore, attention should be paid to the temperature management in the shed in winter and spring.

The highest temperature in the shed generally appears between noon 12 and 2 pm, and after 2 pm, the temperature in the shed gradually decreases, which can drop by 3 ~ 5℃ per hour; The lowest temperature in the shed appears at 5 ~ 6 o'clock before sunrise.

In the management of temperature in greenhouse, corresponding temperature control can be taken according to the changes of temperature in greenhouse and the requirements of temperature conditions in each growth period of tomato. It is generally required to "look at three things", that is, look at the weather, seedling conditions and temperature at that time. Generally, the greenhouse should be kept warm after planting and before returning seedlings, but if the temperature is above 30℃, it should be ventilated for a short time (about 1 hour). After the seedlings are put back, the temperature should be controlled according to the growth stage of the plants (Table 4).

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Table 4 Temperature management indexes of spring tomato at different growth and development stages

In particular, it is easy to form thick frost on sunny nights in winter, so we should pay attention to antifreeze and heat preservation. We can cover the skirt with grass pieces and cover the top film with a sunshade net. Cooling is achieved by ventilation. The principle of ventilation is to ventilate on the leeward side, and gradually increase the ventilation opening from small to large, so shoulder ventilation should be adopted.

(2) Humidity management High humidity is another feature of greenhouse microclimate. Because of the airtight film, the air humidity in the shed can be as high as 70% ~ 100%, which is easy to induce many diseases, such as plants growing in vain and falling flowers and fruits. Therefore, measures must be taken to reduce the humidity in the shed. The main methods are as follows: before planting 10 ~ 15 days, cover with drip-free film; Reasonable ventilation and controlled irrigation; Do a good job of ditching and drainage around the greenhouse.

(3) Light management In winter and spring tomato cultivation, temperature and light are contradictory, and heat preservation measures (covering) will reduce the light transmittance. Therefore, we must coordinate this contradiction: we can choose suitable covering materials and adopt scientific covering methods. Some data show that the light transmittance of new agricultural film is 80% ~ 90%, and some even reach 95%, and the light transmittance of old film will decrease 10% ~ 15%. The light transmittance of anti-aging agricultural film is low, and the light transmittance of drip film is lower than that of non-drip film 10% ~ 20%. In addition, the light transmittance of bamboo-wood greenhouse is about 10% lower than that of steel tube greenhouse. Therefore, it is necessary to use a new drip-free anti-aging film as far as possible, and at the same time, the sunshade net on the top film should be removed as soon as possible in the morning, and the ceiling film and the intermediate film in the shed should also be removed as soon as the temperature is acceptable. Even in rainy days, the cover in the shed should be removed for a period of time (noon), and snowy days are no exception (and the snow on the shed should be removed in time).