How the coverage of nonwovens will directly affect the growth and production of vegetables, mainly in the following areas.

Light transmittance

    The transmittance of the nonwoven fabric with the weight of 20g / m2 was 87% and the weight of 30g / m2 was calculated by the plane coverage method with the JD-3 type illuminance meter in the season with small solar elevation angle in winter. 79%, 72% for 40 g / m2, and 73% for 25 g / m2. Of which 25g / m2 non-woven fabrics for the spunbond production, slightly less light transmission. Nevertheless, these four specifications of nonwovens can meet the requirements of covering vegetables compared to light.

2. breathability

     Non-woven fabric permeability is better than plastic plastic film, with a certain degree of permeability, after the cover does not have to cover the ventilation, labor and labor, the size of the air permeability and non-woven structure of the intermittent size, , But its air permeability and thermal insulation were negatively correlated, that is, insulation with the increase in permeability decreased. According to the determination, 20g / m2 non-woven air permeability of 5 ~ 6m3 / (m2.h), to meet the needs of vegetable growth.

3. Insulation

     Agricultural non-woven fabrics on the main insulation of vegetables in the vegetable leaf temperature, surface temperature and ground temperature have a certain degree of improvement.

(1) Vegetable leaf surface temperature increase According to the winter three sunny days, three cloudy measured lettuce in 20g / m2 non-woven fabric covered with open field (CK), no cover under the test comparison, non-woven fabric covered The average warming value of lettuce in winter was ± 0.75 ℃ when the determination time was 4:00, the temperature was increased at 0.9 ℃, the temperature was increased from 3:00 at 16:00 and 1.6 ℃ at 16:00, 00 when the temperature increase of 0.65 ℃, the highest temperature increase at noon, up to 3 ℃, night cooling stage can still increase the temperature 0.65 ~ 0.75 ℃. Obviously, the increase in leaf temperature is very beneficial to the growth of winter production, in the actual use of the process, in order to improve the effect of night warming, plant foliage should not be close to non-woven fabric cover.

(2) the surface temperature increased, the use of 20g / m2 non-woven fabrics directly covered in winter lettuce, sunny surface average temperature of nearly 2 ℃, cloudy at about 1 ℃, especially at night low temperature, the ground effective radiation Weakened, better insulation effect, up to 2.6 ℃, but the effect of cloudy day is only about 50% of the sunny night.

(3) the increase of the temperature in the ground, still 20g / m2 of agricultural non-woven surface covered with winter lettuce as an example, the determination of soil 5cm, 10cm, 15cm, 20cm different depth of soil warming effect, sunny day were 1.8 ℃ , 1.1 ℃, 1.1 ℃, 0.7 ℃, while the rainy days are lower, respectively, 0.8 ℃, 0.7 ℃, 0.4 ℃, 0.3 ℃. The results show that the warming effect of sunny day is obviously higher than that of rainy days. The warming effect of shallow soil layer is higher than that of deep soil layer. The effect of warming effect can exceed 20cm. In the cold winter, the improvement of soil temperature is beneficial to the absorption of soil moisture and nutrients to the roots of vegetables, so that the root growth is accelerated and robust, so as to promote the growth of aboveground stems and leaves, and improve the resistance of the upper part of the ground. In winter, the effect of soil temperature on crop growth is more important than that of aboveground temperature, and the effect is more obvious.

(4) improve the comprehensive cold-proof capacity, the temperature of the growth of vegetables, increasing yield and increase a great impact. The cold-warming effect of 20g / m2 non-woven fabric is obvious, and it is 3.8 ℃ higher than that of open field under extreme low temperature (-7.2 ℃). According to the relevant information, lettuce seedlings short-term ability to withstand low temperature between -5 ~ 6 ℃, the use of agricultural non-woven anti-low temperature capacity of the limit can reach -9.5 ℃, such as the use of quantitative large non-woven or Nonwovens are used together to further improve the ability to prevent low temperatures.