Enhanced Graft-take Ratio and Quality of Grafted Tomato Seedlings by Controlling Temperature and Humidity Conditions

This study was conducted to enhance graft-take ratio and quality of grafted tomato seedlings by controlling temperature and humidity during the healing and acclimatization processes. Three temperature levels (20℃, 23℃, and 26℃) were carried out to determine optimum temperature on four rootstocks. In addition, twelve combinations of three relative humidity levels (70%, 80%, and 90%) and four temperature levels (17℃, 20℃, 23℃, and 26℃) were set up to evaluate the effect of relative humidity and temperature on the graft-take ratio of grafted seedlings. In the other hand, five relative humidity periods (H0, H1, H2, H3, and H4: 90% relative humidity for first 0, 1, 2, 3 and 10 days and afterwards relative humidity was reduced to 70%, respectively) were examined effect of relative humidity periods on the graft-take and quality of grafted seedlings. The higher graft-take ratios (84.0~87.4%) were showed at 23℃ compared to 20℃ and 26℃ in all rootstocks. Graft-take ratios decreased and number of diseased plants increased at high temperature. The graft-take ratios increased with increasing relative humidity in all temperature levels on the 3 rd and 7 th day after grafting. However, increasing relative humidity significantly increased percent of diseased plants. The graft-take ratio reduced at (26℃) and (17℃) temperature under all relative humidity conditions. The graft-take ratio increased with increasing period of 90% relative humidity. Maximum graft-take ratios were observed in H2 and H3 treatments. Graft-take ratio decreased with increasing 90% relative humidity for 10 days (H4). Diseased plants had not been found in H0, H1, H2, and H3 treatments. Seedling quality was improved through increasing fresh and dry weight of root, compactness, and root morphology of tomato seedlings in H2 and H3 treatments. Therefore, high relative humidity (90%) for first 2 or 3 days and afterwards reduced low relative humidity (70%) at 23℃ condition during healing and acclimatization promoted the graft-take and quality of grafted tomato seedlings.