Abstract
The relative value of the y coordinate of the center of gravity of the leaf area on video image (wilting index) has been proposed as useful for the image diagnosis of the water status of greenhouse vegetables. In order to evaluate the usefulness of this method, cucumber (cv. ‘Tokiwa Hikari 3A’) plants were grown in solution culture in a growth chamber and were subjected to osmotic stress, anoxic stress, and hypoxic stress and the responses of the transpiration rate, stem width and wilting index were compared. Stem width, which seems to reflect continuous changes in the turgor pressure of cells, seemed to be suited to the detection of relatively light water stress. However, for the detection of severe water stress that causes wilting, the wilting index, which seems to be able to detect a threshold value of turgor pressure, was superior. Thus, the use of stem width and the wilting index together was suggested to be useful for the detection of water stress.
