How to choose a shading net?
The main function of shading net is to block strong light and reduce greenhouse temperature. Covering shading net is an important measure for sparse vegetable production in greenhouse during high temperature seasons. However, if an inappropriate shading net is used, it will not only cause the plant to grow excessively, but also be unfavorable for flowering and fruit setting. It is necessary to scientifically and reasonably use shading nets. Don't judge the quality of sunshades based on color: currently, the sunshades sold in the market are mainly black and silver gray. Black shading nets have high shading efficiency and fast cooling, making them suitable for short-term coverage in fields that require careful management in hot summer; The silver gray shading net has a low shading rate and is suitable for light loving vegetables and long-term coverage. The quality of the sunscreen is not determined by the color the final say The color of the sunscreen is added in the process of raw material manufacturing. So, different vegetables should choose different shading nets. For example, tomatoes are a light loving crop. As long as the daily flowering time of 11-13 hours is met, the plant will grow vigorously and bloom earlier. Although the effect of light duration on tomatoes is not as important, the intensity of light is directly related to yield and quality. Insufficient light can easily lead to malnutrition, elongation, and reduced flowering of plants. The light saturation point of tomato is 70000 lux, the light compensation point is 30000~35000 lux, and the general summer noon light intensity is 90000~100000 lux. Black shading nets have a high shading rate of up to 70%. Using black shading nets, the light intensity cannot meet the normal growth needs of tomatoes, which can easily lead to excessive growth of tomatoes and insufficient accumulation of photosynthetic products. The shading rate of most silver gray shading nets is 40%~45%, and the light transmittance is 40000~50000 lux, which can meet the normal growth needs of tomatoes. So it's best to cover tomatoes with a silver gray shading net.
To distinguish which material is made of sunshade nets: There are currently two types of production materials for sunshade nets on the market, one is high-density polyethylene produced by petrochemical enterprises, and the other is reprocessed from recycled old sunshade nets or plastic products. It is understood that sunshades produced with recycled materials not only have low smoothness, a hard feel, and often have a pungent odor, but also have a short service life, most of which can only be used for one year. The high-density polyethylene sunscreen is anti-aging and durable, and its service life can reach 4 years. It is more careful to buy sunscreen by weight: there are two ways to sell sunscreen in the market now: one is by area, and the other is by weight. When choosing, vegetable farmers should not rely solely on one way to purchase. They should carefully compare the materials and density to prevent illegal distributors from selling inferior "heavy" shading nets.
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