EVALUATION OF GRAFT-TAKE USING A THERMAL CAMERA

Presently, in Japan, grafting transplants are widely used for greenhouse cultivation. Automatic machinery for the grafting process was developed by the Institute of Agricultural Machinery in Japan. It is desirable to evaluate the grafted plants as soon as possible after grafting. A method of evaluating grafted plants using a thermal camera was studied. In this study to evaluate the quality of graft-take plants, leaf temperature was measured as the light intensity was varied. A thermal camera with an image processor was used to measure the leaf temperature. The camera could measure temperatures from 20°C to 32°C with sensitivity of 0.8°C. The plants were placed in a growth cabinet in which the temperature was kept at 25°C, and the light intensity was changed from 0 to 67 μEm^-2sec^-1 and from 67 to 0 μEm^-2sec^-1.

It was assumed that if the quality of graft-take was good, the water would move smoothly from the root to the leaf which was grafted, and the leaf temperature would decrease due to vapor transpiration. The results showed that the rate of change in leaf temperature depended on the quality of graft-take. The leaf temperature of the good quality graft-take plants was 2 to 3°C less than that of bad quality graft-take plants. Therefore, the quality of graft-take may be estimated by this method.