First of all, according to the seasonal changes of the year, in strong light seasons (usually accompanied by high temperatures), such as summer, greenhouses and other facilities are used for vegetable production(cheap 72 cell plastic seedling trays suppliers). The RH of dry air is 0 and that of saturated water vapor is 100%(starter trays). For example, the vernal equinox and autumnal equinox have 12 hours of sunshine regardless of whether it is sunny or cloudy.
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For example, in the growth and formation stage of eggplant fruit, the upper limit of light intensity is (5~7)×10°lux, and (8~9)×10°lux can also grow, but the yield and quality are reduced(v12 nursery pots). Correspondingly, the light intensity changes in the shed showed the same changing trend(trade gallon pot). Many vegetable farmers have a one-sided understanding of the high yield of vegetables is that the light is strong and the yield is high(cheap 72 cell plastic seedling trays suppliers).
If the seasonal changes of light intensity are not clear, it is difficult to adjust the light environment according to the seasons(cheap 72 cell plastic seedling trays suppliers). Taking the seasonal variation of solar radiation intensity (light intensity) in the Yangtze River basin as an example, according to the author's research results, the average light intensity in July is 2.2 times the average light intensity in December(thermoform pots). The greenhouse vegetables are produced in winter and spring.
According to the change of seasons, the temperature management of greenhouse vegetable production is carried out in cold seasons(v10 nursery pots). In cold seasons, the production of greenhouse vegetables, due to different types of vegetables, has different requirements for light in the formation stage of their product organs(square plastic nursery pots). Winter is often the main limiting factor(cheap 72 cell plastic seedling trays suppliers). The radiation wavelength composition in the facility is very different from that outside.
Adjust accordingly for different types(cheap 72 cell plastic seedling trays suppliers). For long-day vegetables, the light is important, the dark period is not important, and they can even bloom under continuous light(plastic tree pots). Generally, it is 50%~80% of outdoor. The light intensity of watermelon during fruiting period can be higher, and its light saturation point is about 10×10°lux(hole tray). There are two sources of water vapor in the air: soil evaporation and plant leaf transpiration.
According to the upper limit light intensity requirement of vegetables, the light intensity management of ordinary vegetables can refer to the following indicators(cheap 72 cell plastic seedling trays suppliers): the upper limit requirement of light intensity for leeks is about 2(plastic terracotta pots).5×10 lux, pepper is about 3×10 lux, cabbage and zucchini are about 5×10° lux, cucumber It is about 6×10° lux, eggplant and tomato are about 7×10° lux, and the seedling stage of watermelon is about 8×10° lux.
Different regions, different times of the day, different parts of the facility, and different positions of the sheds, the lighting in the sheds varies greatly, and needs to be understood and adjusted in time(v11 nursery pots). Vegetable farmers' one-sided understanding of high yields of vegetables is that they have strong sunlight and high yields(cheap 72 cell plastic seedling trays suppliers). The light environment in the shed facilities is characterized by low total radiation and weak light intensity(square succulent pots).
In addition, light quality also affects the growth and development of vegetables(cheap 72 cell plastic seedling trays suppliers). Generally speaking, light quality has an impact on vegetable quality(nursery flower pots). For the structure of greenhouse, please refer to questions 47 and 48; For the population structure of crops, please refer to question 7. Soil water can be directly absorbed by plant roots(decorative plastic plant pots). The light management of greenhouse vegetables should be based on the vegetables.
For example, the formation of anthocyanins requires strong red light(cheap 72 cell plastic seedling trays suppliers). Ultraviolet rays can increase the vitamin C in the peel, so the vitamin C content of tomatoes and cucumbers grown in glass greenhouses is not as high as that in the open field(plastic nursery pots for sale). The light transmittance of glass is high, and the light transmittance of plastic film is generally 60% ~ 80%, which decreases with the extension of service time, and dust will also affect it.
It is necessary to adjust and control the light environment of the shed from the main factors limiting the light transmittance(plastic nursery trade pots). There are four main factors affecting the light transmittance of the shed, namely: Outdoor solar radiant energy; Optical properties of covering materials; Structure of greenhouse(plastic nursery tray); Population structure of crops(cheap 72 cell plastic seedling trays suppliers). The influence of light time on the development of some crops is also restricted by temperature.
Outdoor solar radiation can only be regulated from other aspects on the basis of understanding its change law due to different time, region and season changes and is not artificially controlled(v9 nursery pots); The optical performance of the covering material is determined by the optical performance of the selected material. For example, strawberry requires short sunshine when forming flower buds(cheap 72 cell plastic seedling trays suppliers). The higher the temperature, the shorter the sunshine.
In North China, vegetables such as cucumber, rainbow bean and zucchini are planted in the greenhouse(plug trays for sale). The weak light period is from December to march of the next year. Electric lights and reflective screens can be used to fill the light, and they can be removed in April, otherwise Lai seedlings will be damaged by heat(cheap 72 cell plastic seedling trays suppliers). Long wave radiation increased(plug flats). The light distribution in the facility is extremely uneven in time and space.
Cucumber illumination (1 ~ 4) × 10 ° lux, shading shall be conducted in case of exceeding, and the temperature shall be controlled at about 25 ℃(cheap 72 cell plastic seedling trays suppliers). Uncover late in the morning, cover early in the afternoon, and shade appropriately at noon to create a growth environment with low temperature, weak light and short sunshine to induce male melons(sureroots deep cell plug trays). Shading by mat, shading net and pe net can increase the output by about 30%.
The light environment requires high light transmittance, large light-receiving area, and uniform light distribution(72 cell propagation tray). The so-called relative Hu humidity (abbreviated as RH) refers to the ratio of water vapor pressure in the air at a certain temperature to saturated water vapor pressure at that temperature, expressed by a percentage sign(cheap 72 cell plastic seedling trays suppliers). When the air temperature rises, the saturated water vapor pressure increases and the relative humidity decreases.
Many greenhouse vegetables grow in a relatively closed environment, so the management of water environment is particularly important(cheap 72 cell plastic seedling trays suppliers). The main source of water in soil is irrigation(plastic plant pots for sale). Generally speaking, the soil moisture content in the facility is greater than that in the open ground(terracotta plastic plant pots). It is not only a good solvent for various nutrient elements in the soil, but also plays a role in regulating soil temperature and affecting soil fertility.