Vegetable seedling grafting in Japan

In vegetable production in greenhouses, most of the damages by, continuous cropping are caused by soil-borne diseases and nematodes. Grafting of fruit-bearing vegetables is popular in Japan to control damage from Fusarium wilt, bacterial wilt, and nematodes. The proportions of the area using grafted plants of watermelon, cucumber, melon, tomato and eggplant were 57%, 59%, and 59% of the total production area in 1980, 1990, and 1998, respectively. Plants have been grafted onto various rootstock species and cultivars by various grafting methods. Recently, tube grafting method has been developed and became popular for plug-cultured seedlings. Healing and hardening are key factors for the survival of grafted plants. Exposing seedlings to sunshine and withholding water supply for two to three days prior to grafting increases success. For graft healing, high humidity should be maintained so as not to dry the cut surfaces. The hardening process after healing requires frequent checking of the state of grafted plants to increase survival, especially under conditions of temperature fluctuations. Grafting provides increased disease tolerance and vigor to crops and should be considered a low-input, sustainable horticulture practice for the future.