For example, severe cooling can easily lead to serious inhibition of vegetable growth, and sometimes even directly freeze crops. Especially in the south, this phenomenon is very common. In the north, because there are greenhouses, there are relatively few cases of direct freezing damage, but in the north, greenhouses may collapse because of heavy snow, causing very serious losses.
Therefore, when winter comes, (in fact, it is not only winter, but also autumn and early spring, which are the high incidence periods of freezing injury or chilling injury. It is very important to help vegetables resist low temperature.
1, the adaptive temperature range of tomatoes is still relatively wide, but it must be remembered that if tomatoes are below 15℃ for a long time, it will bring disadvantages to the growth of tomatoes.
There are several key data nodes.
(1) When the temperature is lower than 15℃, the growth of tomato will slow down. (2) When the temperature is lower than 65438 03℃, the seedlings hardly grow. (3) The temperature below 65438 00℃ will affect germination. (4) When the temperature is lower than 8℃, the root growth of tomato will be affected. (5) When the temperature is lower than 5℃, the growth of stems and leaves stops completely. (6) If the temperature is lower than 65438 0℃, tomatoes will freeze to death.
2. Eggplant is also a kind of crop with large planting area, especially in greenhouse. Its temperature adaptation range is slightly narrower than that of tomato, and its low temperature tolerance is not particularly strong.
If the temperature of eggplant is lower than 20℃, it can grow normally, even if it grows slowly, it will affect the results. For example, you can pick an eggplant ten days or seven days ago. If it is below 20 degrees, it may take 15~20 days to pick an eggplant.
Eggplant, like tomato, has a temperature node of 15℃. If the temperature is lower than 15℃, eggplant will be seriously affected.
Therefore, when the temperature is 15 ~20℃, heat preservation and heating measures should be taken. If we don't spray some and preheat at this time, the output and quality will definitely be affected.
In addition, if you plant eggplant, you must remember that if the temperature in the north is too low and the air conditions are not suitable, try to plant eggplant as little as possible, and the south is relatively better.
Pepper is more delicious than eggplant and tomato. The temperature it can tolerate is relatively low. As long as the temperature is above 10℃, its growth is relatively normal.
But if it is lower than 10℃, it will affect its germination.
But for some special peppers, such as colored peppers, the symptoms of freezing (softness) began to appear at 5℃. Therefore, everyone must remember that if you plant colored peppers, the temperature should be higher, not lower than 5℃. In fact, most pepper varieties can tolerate the low temperature of about 3℃ for a short time, but the time cannot exceed 48 hours.
In addition, if the temperature is below 0℃, pepper will die in a large area.
Therefore, for most peppers, if the temperature starts to drop below 10 degrees, it is necessary to take heat preservation measures!
4. Cucumber is tender. In the north, cucumber topping often occurs in winter.
If the temperature is lower than 18℃, cucumber seedlings are basically difficult to grow. If the temperature is lower than 13℃, the seedlings will stop growing and some seeds will be difficult to germinate. If cucumber seedlings are cultivated, it is very important to control the temperature above 13℃.
Therefore, when the temperature is 18℃, it is necessary to take some measures for cucumber, such as spraying some antifreeze and taking some warm-keeping measures.
5. Green beans are also sensitive to temperature. Green beans have a very critical temperature node, which is 15℃.
If the temperature is lower than 15℃, you will find that even if it has flowers, it will not bear fruit or yield. When the temperature is lower than 13℃, the seedlings and roots stop growing and no nodules are produced. If the temperature is below 8℃, the seeds can't germinate. When we grow seedlings or beans, the low temperature must be kept above 8℃, otherwise it is easy not to germinate.
There is also an extreme low temperature, which is 3℃. If the temperature is lower than this extreme low temperature, plants will suffer and die.
The above is green beans, and there is another kind of beans called cowpea, which has a slightly stronger tolerance to low temperature than green beans. You can have a look.
6. Celery is a relatively low-temperature tolerant crop, which can tolerate MINUS 5℃.
As long as your greenhouse temperature is higher than 5℃, it can grow normally. But if the temperature is lower than 5℃ for a long time, its quality will be affected. For example, the rod is thin, or the blade ratio may be affected.
But when planting celery, we should pay attention to the temperature can not be lower than 4℃. If it is lower than 4℃, it is difficult for seeds to germinate.
7. Spinach grows below 12℃ and grows slowly. Below 4℃, it is difficult for seeds to germinate, and below 2℃, they will stop growing.
But the cold tolerance of spinach is relatively strong, that is to say, even if you lower the temperature below 0℃, such as -5℃ and-12℃, it may not freeze to death, but it will not grow. Under this condition, it is basically dormant, but it is still alive.
In production, we can use this characteristic to reasonably control the growth of spinach. For example, the spinach market is not good at this time, and you don't want it to grow so fast. What can we do? We can lower the greenhouse temperature appropriately, lower the constant temperature to below 12℃, slow down the spinach, and then raise the greenhouse temperature when the price of vegetables is high.
But we plant spinach mainly to harvest its leaves, so we must find ways to keep the growth temperature of spinach above 12 degrees, so that it can grow faster.