With controllable temperature, humidity, light, water and fertilizer conditions, the greenhouse system has become an ideal planting carrier for high value-added crops. Different crops have significantly different sensitivity to the environment. Those with strict requirements for growth conditions and high economic value can better play the advantages of greenhouse precision control and achieve a double improvement in quality and yield.
Tomatoes are representative crops of greenhouse vegetables. Their optimal growth temperature （25-28℃ during the day and 15-18℃ at night） can be accurately maintained by the temperature control system. The relative humidity during the flowering period is stable at 60-70%, which can significantly reduce the incidence of gray mold （80% less than open field planting）. In a greenhouse environment, the yield of tomatoes can reach 8-12kg/㎡, which is 50% higher than that of open fields, and the sugar content of the fruit is increased by 1-2 percentage points, and the shelf life is extended by 3-5 days.
Colored peppers are sensitive to light (requiring 30,000-50,000 lux photosynthetically active radiation). The greenhouse lighting system can make up for the lack of light in winter, extending the harvest period from 3 months in the open field to 8 months. By regulating CO₂ concentration (maintained at 800-1000ppm), the weight of single pepper fruit increased by 15%, the rate of deformed fruit decreased to less than 5%, and the proportion of export-grade products increased to more than 60%.
The flowering process of Phalaenopsis is sensitive to temperature （the temperature difference between day and night needs to be controlled at 5-8℃）.The greenhouse temperature control system can accurately control the temperature fluctuation at ±0.5℃, which promotes the uniformity of flowering to more than 90%, which is 40% higher than the natural environment. The relative humidity of the air is kept stable at 70-80% to avoid the tip of the leaves from burning. With the addition of LED light with a specific spectrum (the proportion of blue light is increased to 30%), the flowering period is shortened by 15 days, and the uniformity of the length of the flower arrow is increased to 85%.
Anthurium can achieve year-round production in the greenhouse. By adjusting the duration of light (12-14 hours/day) and the EC value of water and fertilizer (1.0-1.2mS/cm in the seedling stage and 1.5-1.8mS/cm in the mature plant), the annual flowering volume of a single plant reaches 8-10 flowers, which is 3-4 more than that of open-field planting. The color saturation of the spathe (Lab value a* increased by 10%) is significantly improved, and the commodity value increases by 20%.
Strawberries are cultivated on elevated platforms in greenhouses, and with a ground temperature control system (root temperature maintained at 18-20℃), they can be listed 2 months in advance (from November to May of the following year), with an output of more than 2,000kg per mu. Through bee pollination and coordinated regulation of temperature and humidity (humidity during flowering period 50-60%), the deformed fruit rate is controlled below 3%, and the sugar-acid ratio is increased to 12:1, which meets the needs of the high-end market.
As a tropical crop, pitaya can bear fruit normally in temperate greenhouses through a heating system (the night temperature in winter is not less than 15℃) and supplementary lighting (the annual cumulative light reaches 2,000 hours). The weight of a single fruit is increased to more than 500g, and the soluble solids content is 18%, which is 3 percentage points higher than that of open-field planting, achieving a commercial breakthrough in "southern fruit and northern planting".
Dendrobium candidum has strict requirements on the growth environment (air humidity 80-85%, scattered light intensity 20000-30000lux). The greenhouse's atomization humidification and shading system can perfectly match its needs. The survival rate of tissue culture seedlings is over 95%, 20% higher than that of greenhouse cultivation. By precisely controlling the harvest period (growth cycle 24 months), the content of dendrobium polysaccharides is stable at more than 25%, in line with the pharmacopoeia standard (≥20%), and the batch difference rate is less than 5%.
Anoectochilus roxburghii relies on specific temperature and humidity (20-25℃, humidity 75-80%) and weak light environment. The environmental control of the greenhouse can increase its total flavonoid content by 10%, and the heavy metal content (lead, cadmium) is controlled below 0.1mg/kg, meeting the organic certification standard. The market price is 30%-50% higher than that of open-air cultivation.
When choosing greenhouse crops, you should give priority to the "three highs" categories: high environmental sensitivity （such as Phalaenopsis and Dendrobium candidum）, high economic value （such as bell peppers and strawberries）, and high off-season premiums （such as winter tomatoes and pitaya）. These crops can give full play to the advantages of a controlled environment in the greenhouse system, achieve uniform quality and normalized supply, bring stable income to growers, and meet the market's continued demand for high-quality agricultural products.
