Greenhouse, a relatively closed production system, will play an important role in meeting the demand for food growth in the future. In recent years, the lack of greenhouse light has attracted more and more attention. On the one hand, the decrease of greenhouse light transmittance caused by greenhouse orientation, structure and covering material characteristics, on the other hand, the lack of greenhouse crop light caused by climate change, such as continuous rainy and rainy weather in winter and early spring, frequent haze weather and so on. Insufficient light has a direct negative impact on greenhouse crops, causing serious losses to production. Plant supplementary light can effectively alleviate or solve these problems.
Incandescent lamp, fluorescent lamp, metal halide lamp, high pressure sodium lamp and new LED plant lighting beads have been or are being used in greenhouse lighting. Therefore, this paper systematically summarizes the previous research results and their production and application status, and provides a reference for the selection and application of light sources in greenhouse supplementary lighting.
Difference of High Pressure Sodium Lamp and LED Plant Supplementary Light Bead Lighting
Differences in Applicable Conditions and Life Spans
High-voltage sodium lamp is the third generation lighting source. It has a wide range of applications under conventional alternating current, high luminous efficiency and strong penetration ability. Its maximum life is 24,000 hours, and the minimum can be maintained at 12,000 hours. Sodium lamp is a kind of thermal light source, because it can produce heat at the same time of illumination. In the use process, there are also self-extinguishing problems. As the fourth generation of new semiconductor light source, LED is driven by DC. Its lifetime can reach more than 50000 hours, and its attenuation is small. As a cold light source, it can be close to plant irradiation. Comparing LED with high pressure sodium lamp, it is pointed out that LED has higher security, does not contain harmful elements and is more environmentally friendly.
Difference of the Effects of High Pressure Sodium Lamp and LED Supplementary Light on Crops
A large number of production practices and scientific research in agricultural production have proved that artificial plant light supplementation can not only increase crop yield, shorten the planting cycle, but also effectively improve crop quality, which is an important means of ensuring efficient production in modern agriculture. In the process of seedling raising and greenhouse crop management, using high-pressure sodium lamp and LED to supplement light can promote crop growth and development, and change crop yield, morphology and physiological indicators.
Differences in Yield and Quality
The ultimate goal of crop cultivation is high yield and high quality. The quality of pepper, tomato and eggplant seedlings could be improved by supplementing light with LED. The single fruit quality and yield of tomato increased significantly under 10 hours of supplementing light. The effect of LED light supplementation on cucumber production is also shown in Cucumber planting. LED can improve the quality of grape fruit, among which the blue light treatment is the fastest growing, the single fruit quality is higher, the sugar content is the highest, and the single fruit quality is the highest when the UV light treatment is mature. In the same way, 70W high pressure sodium lamp had a significant effect on the yield of strawberry, with an increase of 17.9%. High pressure sodium lamp and LED light supplement had significant effects on plant morphology. The visual fruit quality of cucumber was also improved by supplementing LED side light. On the basis of sodium lamp, add LED. Compared with only sodium lamp treatment, cucumber color is brighter.
