In summer, with the increase of light intensity and temperature, the main factors affecting the growth of vegetables are too high temperature and light intensity in the shed. To reduce the temperature and light intensity in the shed, the sun protection net for plants is the first choice. Some vegetable farmers reported that although the temperature decreased after using sun protection nets for plants, the growth of cucumber is weak and the yield is low. After detailed understanding, we believe that this is caused by the high shading rate of the sunscreen used. There are two main reasons for the high shading rate: one is the problem of using method; the other is the problem of the net itself. For the use of the net, we should pay attention to the following aspects:
First, select the sun protection net for plants correctly. There are mainly two colors of sun protection nets for plants in the market: dark and silver gray. The rate of dark sun protection nets for plants is high, and the cooling effect is good. However, it has a great influence on the light coordination. It is more suitable to use on leafy vegetables. If it is used on some light loving vegetables, the covering time should be reduced. While the cooling effect of the silver-gray sun protection net for plants is not as good as the dark one, but it has little effect on the light synergism of vegetables. It can be used in eggplant, fruit and other light loving vegetables.
Second, use the sun protection net for plants correctly. There are two ways to cover up the sun screen: all cover up and bower-type cover up. In actual use, bower-type cover up is better because the atmosphere is smooth and the cooling is better, so there are more ways to use it. When it is applied, the framework of the arch shed is used to cover the sunshade at the top, and a ventilation belt of 60-80cm is left on it. If cover has film, the sun protection net for plants cannot cover up on film indirectly. The user should leave more than 20 centimeters free and use wind to cool down the temperature.
Although covering the sun protection net can reduce the temperature, it also reduces the light intensity, which has a negative impact on the photosynthesis of vegetables, so the covering time is also very important. It should be avoided to cover the whole day. It can be covered between 10 a.m. and 4 p.m. according to the temperature. When the temperature drops to 30℃, the sun protection net can be removed, and do not cover in cloudy days, so as to maximize the reduction of adverse impacts on the vegetables.