Compared with outdoor lighting, growers should have a clear understanding of the actual lighting that plants in their greenhouse can get, and then determine the supplementary lighting space that needs to be filled. The design, location, and equipment use of each greenhouse will affect the actual indoor lighting. Growers can obtain the average light parameters over the years through the greenhouse or the weather station of the city. It is worth noting that the northern solar altitude angle is low in winter.
Tomatoes are light-loving plants and need strong light during the growth process. The light requirements for growing tomatoes indoors is 400-500umole/m2/ which is an ideal state. Before the light intensity reached 400 μmol/m2/s, the net photosynthetic rate of tomato leaves increased rapidly with the increase of light intensity. When the light intensity enters the range of 500-800μmol/m2/s, the increase rate of the net photosynthetic rate slows down. After more than 800μmol/m2/s, it is close to saturation. Considering the supplementary light benefit of the greenhouse, when the external natural light intensity exceeds 450W/m2, the top light LED is not recommended to start.
The specific light supplement time can be calculated according to the current crop needs, the actual natural light in the greenhouse and the installed supplement light intensity.