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The selection of shading nets for shade and light loving crops varies greatly

On the market, there are mainly two colors of sunshade: black and silver gray. Black has high sunshade rate and good cooling effect, but it has a great impact on photosynthesis. It is more suitable for shade loving crops. If it is used on some light loving crops, the coverage time should be reduced. Although the cooling effect of silver gray shading net is not as good as that of black shading net, it has little impact on crop photosynthesis and can be used on light loving crops.

Correctly use the sunscreen to lower the temperature and raise the illumination

There are two methods of sunshade coverage: full coverage and pavilion type coverage. In practical application, pavilion type coverage has better cooling effect due to smooth air circulation, so it is used more frequently.

The specific methods are:

Use the skeleton of the arch shed to cover the sunshade net on the top, leaving a ventilation belt of 60-80cm above.

If the film is covered, the sunscreen cannot be directly covered on the film, and a gap of more than 20 cm should be left to cool down with wind.

Although covering the shading net can reduce the temperature, it also reduces the light intensity, which has a negative impact on the photosynthesis of crops. Therefore, the covering time is also very important. It should avoid covering all day. It can be covered between 10 a.m. and 4 p.m. according to the temperature. When the temperature drops to 30 ℃, the shading net can be removed, and it should not be covered on cloudy days to reduce the adverse impact on crops.

When we buy sunshade nets, we should first make clear how high the sunshade rate of our shed is.

Under direct sunlight in summer, the light intensity can reach 60000 to 100000 lux. For crops, the light saturation point of most vegetables is 30000 to 60000 lux. For example, the light saturation point of pepper is 30000 lux, that of eggplant is 40000 lux, and that of cucumber is 55000 lux.

Excessive light will have a great impact on crop photosynthesis, resulting in blocked absorption of carbon dioxide, excessive respiratory intensity, etc. This is how the phenomenon of “midday rest” of photosynthesis occurs under natural conditions.

Therefore, using shading nets with appropriate shading rate can not only reduce the temperature in the shed around noon, but also improve the photosynthetic efficiency of crops, killing two birds with one stone.

Considering the different lighting needs of crops and the need to control the shed temperature, we must choose a shading net with appropriate shading rate. We must not be greedy for cheap and choose at will.

For the pepper with low light saturation point, the shading net with high shading rate can be selected, for example, the shading rate is 50%~70%, so as to ensure that the light intensity in the shed is about 30000 lux; For the crops with high isochromatic saturation point of cucumber, the shading net with low shading rate should be selected, for example, the shading rate should be 35~50% to ensure that the light intensity in the shed is 50000 lux