Air-circulator effects on the greenhouse environment and tomato photosynthetic parameters in a Chinese solar greenhouse
In view of the lack of airflow and the inhomogeneous distribution of temperature during daytime under conditions of closed cultivation in the solar greenhouse, the applicability of an air circulator was tested in this study in a Chinese solar greenhouse of Tongzhou District, Beijing. The effects of the air circulator on the indoor airflow field, temperature and humidity field as well as growth of the crop (tomato) were also tested. The applicability of different types of air circulators in the Chinese solar greenhouse was further analyzed. The results showed that the usage of an air circulator brought effective airflow disturbance to the Chinese solar greenhouse and improved the airflow environment in the canopy space. The canopy temperature was reduced by 3-4°C before and after noon, the relative humidity increased by approximately 8%, and the maximum temperature was inhibited effectively at noon. The temperature difference between the north and south of the Chinese solar greenhouse was reduced, and the spatial distribution of temperature was increased. In terms of growth tests, flow disturbance increased the net photosynthesis rate (Pn) of tomato leaves by 31%, and stomatal conductance (Gs) by 57%. The maximized coverage of the designed wind speed (0.5 m s-1), and the best disturbing flow could be achieved with the most suitable air circulator (SFG2.5-2) placed 1-2 m above the canopy. The study showed that the usage of an air circulator could disturb the air in the Chinese solar greenhouse effectively, improve the distribution of temperature and humidity as well as provide a suitable environment for plant growth.
Zhuang, Y., Zhang, Y., Zhao, S., Song, W., Ma, C., Chen, X. and Zhang, T. (2018). Air-circulator effects on the greenhouse environment and tomato photosynthetic parameters in a Chinese solar greenhouse. Acta Hortic. 1227, 197-204
Chinese solar greenhouse, CSG, air circulator, environmental parameter, growth