Abstract
Control of water stress to the plant is one of the important technologies for greenhouse and field cultivation. The quality of the crops might be improved by optimizing control of water stress. In this study, the plant's responses to the randomly varying two levels of light intensity were measured, and the frequency characteristics of the plant were calculated. Cross correlation functions with varied light intensity and transpiration, diameter, and leaf temperature were calculated. The result showed time lag of these functions were about 4min., 8min., and 1min. respectively. The step response of the lighting to the plant was also measured, and the frequency characteristics under random lighting condition and from step response showed good agreement.
