The main function of the film is to control the temperature, light and humidity in the shed and prevent the influence of the external environment. Therefore, when selecting the film, the transparency, moisture retention, and service life of the film should be considered.
1. Transparency. The transparency of the shed film is good, and the solar energy in the shed is more, which is more conducive to the growth of the crop under certain conditions, and can also increase the temperature inside the shed, and can improve the yield and quality of the product. The drip-free and drip-film that are common on the market have a great influence on the light transmission of the film. After the water droplets are formed on the non-drop film, it will flow down the film surface and will not easily form aggregates. It is not easy to flow down and it affects the light transmittance when a large amount of material is collected. Different colors of the shed film are selective to the light entering the shed, for example, the violet ray pattern can absorb and reflect the purple light, which has a great effect on preventing the growth of stem and leaf vegetables. Therefore, for some vegetables with stems and leaves as the main ingredient such as leeks, celery, Chinese cabbage and other optional use of purple film.
2. Insulation moisture retention. In cold winter and spring seasons, the heat preservation and moisture retention of the greenhouse film plays an important role in maintaining the temperature and humidity in the greenhouse and ensuring the normal growth of the crop. Therefore, the film used in the winter and spring seasons is preferably of a thicker, light-transmissive, and low-temperature resistant type.
3. Useful life. The common filming time in the market varies from a few months to several years. In general, the longer the service life, the higher the price. However, the useful life of the film is not as long as possible. If the film is used for a long time, the film will have a certain degree of aging, and the light transmittance and heat preservation effect will be reduced. If the time limit is too short, it needs frequent purchase and replacement to increase work. the amount. Therefore, if it is used only for a short period of time, it will use a type with a shorter life span. If it is used for a long time, it will be purchased according to actual conditions.
The difference between the taste of purple onion and yellow onion
Purple onions and yellow onions also have a big difference in taste. Purple onions have a lighter spicy taste and a slightly sweet taste. They can be eaten raw, but the yellow onions are particularly spicy. They cannot be eaten raw and are suitable for frying. Eat after making or making soup. In addition, the purple onion has relatively thick flesh and high juice content, while the yellow onion has very thin flesh quality and low juice content.
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