How to water greenhouse vegetables in winter and spring

The air temperature is low in winter and spring, and the water temperature is also low. after each watering, the ground temperature will drop greatly, which not only leads to the abnormal growth of greenhouse vegetables for several days, but also induces many humidity-loving diseases such as Botrytis cinerea, downy mildew and leaf mildew due to the increase of humidity in the shed after watering, which directly affects the yield, quality and benefit of vegetables. So, how can watering achieve the best results? Specifically, the following points should be done:

First, take a look

1. Look at the growth. Look at the plant growth, usually when the plant is short of water, the leaves will wilt, the growth will weaken, and the navel rot of fruit will occur more often, so water should be replenished in time.

2. Look at the soil moisture. To look at soil moisture, if watering in the greenhouse soil is not dry, not only is not conducive to improve the soil temperature, but also easy to lead to poor soil permeability, resulting in anoxia of roots, resulting in retting roots, the phenomenon of yellow leaves.

3. Look at the weather. Be sure to watch the weather forecast before watering, not only to choose sunny days to water, but also to ensure that there are 2-3 days of sunny days after watering, so as to avoid overcast and rainy weather after watering, resulting in increased humidity in the shed, lower ground temperature, and frequent occurrence of diseases. In the deep winter season, it is more necessary to pay attention to the fact that it is not suitable to water in the first two days after a cloudy day.

4. Look at the ground temperature. The daily average ground temperature suitable for vegetable growth is about 22 ℃, while in the deep winter, the temperature in the interior of the greenhouse is mostly 15 ℃-20 ℃. If the watering is excessive or the watering time is not right, it will make the ground temperature drop rapidly, cause root injury, and endanger the growth of the aboveground part of the plant. Therefore, watering at low temperature had better be carried out after pulling the grass in the morning.

Second, pay more attention

1. Pay attention to covering the plastic film. Plastic film mulching can not only reduce ground water evaporation, maintain soil moisture, reduce air humidity and reduce the occurrence of diseases, but also increase ground temperature and accelerate the growth rate of vegetables.

2. Pay attention to moderate watering. Winter and spring greenhouse vegetable watering, generally follow the principle of no shortage, dry rather than wet, keep the soil water content in the crop rhizosphere at about 60%, prevent excessive frequent watering, and avoid flooding. Excessive watering is easy to reduce the air temperature and soil temperature in the greenhouse, which is disadvantageous to the growth of crops. The greenhouse vegetables in winter and spring should be watered frequently with small water, or irrigated plant by plant with a kettle, which can basically meet the needs of crop growth, and prevent the temperature and humidity in the greenhouse from decreasing obviously, so as to restrain the occurrence of a large number of diseases and insect pests.

3. Pay attention to timely watering. When the vegetables wilt and the tendrils cannot stretch normally, it means that there is a shortage of water and should be watered in time. Watering should be carried out around noon on a sunny day and properly ventilated and wet after watering to prevent excessive humidity in the shed, resulting in the spread of diseases and insect pests. Especially Botrytis cinerea of tomato and downy mildew of cucumber are easy to occur under the conditions of high temperature and high humidity.

4. Pay attention to the regulation of water temperature. When the difference between the water temperature and the temperature in the greenhouse is more than 5 ℃, it is easy to cause root damage. It is better to use deep well water with higher water temperature, or pre-storage irrigation in the shed.

5. Pay attention to dark irrigation under plastic film. For greenhouse vegetables such as melons, eggplant fruits and beans, plastic film mulching should be used during cultivation, and dark irrigation under plastic film should be used during irrigation. Plastic film can be used to heat water temperature and ground temperature, restrain excessive evaporation of water, prevent excessive humidity in the greenhouse and avoid the spread of diseases and insect pests.