Why do you need to cool down at night when you grow vegetarian vegetables in greenhouses?

In nature, there is a temperature difference between day and night. During the day, the temperature is high and the light is sufficient, the plant grows quickly, and the photosynthesis response is fast. At night, when the temperature is low and there is no light, photosynthesis stops, and plants consume less nutrients, and begin to convert the organic matter absorbed and photosynthesized during the day into nutrients and store them in the body.

If the temperature at night remains at the same level as during the day, the crop will maintain a relatively fast "metabolism" at night, and the respiration of the plant will consume a lot of nutrients, and the organic matter produced by photosynthesis during the day without light at night will be consumed by the crop itself.

In our daily life, we all experience that crops grown in areas with a large temperature difference between day and night are more nutritious, richer and tasty than the same crops grown in areas with small temperature differences. For example, the growth rate of apples, rice, and watermelons in the north is slower than that in the south, and the ripening cycle is longer, but the quality is significantly better than that in the south.

Therefore, greenhouse planting should be based on the local environment, and the temperature in the greenhouse should be lowered at night as appropriate to form a good temperature difference between day and night. In this way, water and fertilizer consumption can be reduced, and the quality of crops can be maximized.

Cooling at night is to reduce the respiration of vegetarian plants to reduce their consumption of their own nutrients, fundamentally speaking, appropriate cooling at night is used to widen the temperature difference between day and night, which is conducive to nutrient accumulation Plant growth, can improve the speed of plant growth and the quality of plants.

The vegetables grown with a large temperature difference between day and night are more delicious, which is why vegetables are better in winter, the accumulation of nutrients by photosynthesis during the day and the low temperature at night The nutrients consumed by plant respiration are less, and the plants accumulate more nutrients in a day.

1. Chili peppers. Like high temperature, the temperature of germination is 30-45, the suitable temperature for growth is 26-30 during the day, 18-22 at night, the temperature below 15, the seed can not germinate, and the flowering can not be fertilized. In cultivation, the greenhouse temperature must be kept at 20-25, and if it is lower than 18, it will not grow normally.

2. Tomatoes. It likes high temperatures, and 25-30 is the ideal germination temperature. The suitable temperature for growth is 27 during the day and 17 at night.

The lower limit of the ground temperature during the cultivation period is 10, the minimum temperature according to the growth is 5, the most suitable temperature is 28, and the maximum shall not exceed 38.

3. Celery. Celery likes to be cold, and the required growing temperature is 20-22 during the day, 15-18 at night, and the temperature difference between day and night is 4-5. The ground temperature is required to be 18-20, and the minimum should not be less than 3-6.

The late stage is not less than 6-8, otherwise it will not be able to grow and develop normally.

Fourth, cucumbers. The requirements for temperature are stricter, the suitable temperature is 24-26 during the day, 14-15 at night, the lower limit of low temperature is 10-12, the temperature stops growing below 10, and the root activity above 30 is weak and the leaves are atrophied. The seedling growth period should not be lower than 18, and the minimum temperature is 20-23.

1. Lighting adjustment. Most vegetables have a light saturation point of 50,000 lux (the light intensity exceeds the light saturation point, which is not good for crop growth), but watermelon and tomato can reach 7 80,000 lux, cabbage, cabbage and peas are 40,000 lux, pepper is 30,000 lux, and vegetable corn can reach 100,000 lux. Vegetables requiring strong light include corn, watermelon, melon, tomato, eggplant, etc., which grow and develop well under strong light conditions, and the yield and quality decrease when the light is insufficient; Vegetables suitable for medium light intensity include cabbage, cabbage, radish, carrot, garlic, onion, pepper, etc.; Vegetables that are more resistant to low light include lettuce, celery, spinach, ginger, etc.

It is necessary to choose to plant in the shed according to the requirements of the light conditions of the cultivated vegetables. If you need strong light, try to make it have good lighting, and if you need medium strong light or weak light, you can consider covering shade nets or intermittent and intercropping in different seasons.

2. Temperature regulation. Among the environmental conditions affecting the growth and development of vegetables, temperature is the most sensitive, and at the optimal temperature, vegetables grow and develop rapidly, photosynthesis is vigorous, and the carbohydrates produced and accumulated are the most, which can improve the yield and quality. During the day, sunlight penetrates the film into the greenhouse, raising the temperature of the soil and other objects.

These objects, in turn, release heat into the space in the form of long-wave radiation. Because the covering materials such as film and straw mat at night prevent part of the long-wave radiation from penetrating, this part of the heat is left in the shed to improve the air temperature, and because the heated air in the greenhouse is not easy to be blown away by the wind, it is also the reason for the warming of the shed.

3. Regulation of water contention. Moisture conditions are mainly air temperature and soil moisture content. Different vegetables require different amounts of water.

The same vegetable needs different amounts of water at different stages of growth and development. In the plastic greenhouse, due to the good air tightness, it is less affected by the external rain. In the absence of ventilation, the relative temperature in the shed is high due to the action of soil evaporation and crop transpiration.

The temperature is too large, easy to cause diseases, reduce the air temperature mainly through natural ventilation and exhaust temperature, low temperature season to put a small wind at noon, put the top wind, if there are conditions, try to shake the foot wind, to avoid hurting the mu. In the high temperature season, it should be put in early and let go of the wind. It is necessary to irrigate reasonably according to the water requirements of different crops and different growth periods of crops.

Recently, with the arrival of autumn and winter, the temperature is gradually decreasing, at this time, greenhouse growers are worried about the problem of frost damage, every year will be done in advance of anti-freezing measures, because the greenhouse investment is not small, once the vegetables are frozen, it is very likely to lose money.

So, what are the dangers of low temperature to vegetable growth? What are the warming measures for greenhouses? Let's take a look.

What are the hazards of low temperature to the growth of vegetablesUsually there are two kinds of low temperature obstacles: cold injury and freezing injury: low temperature injury above zero is called cold injury, and low temperature injury below zero degree is called freezing injury.

When vegetables encounter low temperature, especially cold snap invasion or sudden cooling or rainfall, they will show a variety of symptoms, such as seedlings encounter low temperature, cotyledons are raised, the back of the leaf is rolled upward, and the leaf edge gradually wilts and dries up; If the low temperature lasts for a long time, the leaves are dark green and dull, the growth point of the terminal bud is frozen, and the growth of the root system is hindered, resulting in the formation of deformed flowers, resulting in low temperature flower drop or deformed fruits; The fruit is not easy to color and ripen or the color is light to affect the quality, and the serious plants are soaked in water, and the stems and leaves are dry and die. State scrambled.

Greenhouse warming measures: 1. All vegetables in vegetable greenhouses are ridged and cultivated.

The high ridges have a large surface area, receive more sunlight during the day, and absorb more heat from the air, so they heat up quickly.

However, the ridge should not be too high and too wide, generally 15 20 cm high and about 30 cm wide.

2. Covering the plastic film can increase the ground temperature at 10 cm by an average of 2 3, and the ground low air temperature can be increased by about l.

At the same time, because the plastic film is not breathable, it can inhibit water evaporation, reduce the number of watering, and indirectly increase the ground temperature.

3. The roof behind the vegetable greenhouse is covered with advanced thermal insulation material polystyrene board, and wheat straw is not used for heat preservation, because although the heat preservation effect of wheat straw is good, it is easy to decay and has a short service life.

3. Hang a plastic film reflection on the back wall of the greenhouse to improve the light intensity of the cultivation bed, so that the heat stored in the wall is slowly released indoors at night, which can maintain a higher temperature in the second half of the night and prevent the freezing of seedlings.

4. Multi-layer coverage, which is a common warming method.

To maintain the tightness of the greenhouse film, build a shed in the shed or cover the small arch with insulation materials, cover the film at night, and cover the film with grass, but now it is generally used to use black-hearted quilts.

5. Keep the shed film clean, increase the amount of light, and increase the temperature in the shed.

The heat in the shed mainly comes from solar radiation, and when the sunlight enters the shed through the greenhouse film, due to the "greenhouse effect", a part of the light energy is converted into heat energy.

6. Using the warming block, today, I will bring you a product from Shandong Liaocheng Science and Technology Innovation Agricultural Science and Technology - greenhouse warming block, which can help the greenhouse increase by 4-7 degrees.