THE HISTORY AND PRESENT STATE OF THE GRAFTING OF CUCURBITACEOUS VEGETABLES IN JAPAN

Research on vegetable grafting and the spread of methods for this in Japan began around 1920 with a study on watermelon. Cucurbita moschata was initially used as a rootstock with watermelon to prevent fusarium wilt. In the 1930s, watermelon cultivation using rootstocks from bottle gourd or wax gourd, especially bottle gourd, was rapidly adopted after suitable rootstock species and accessions had been selected and a stable grafting method using cotyledonary-stage seedlings had been developed. From the 1950s through to the 1970s, sudden wilt of bottle-gourd-grafted watermelon caused by the pathogens Fusarium oxysporum f. sp. lagenariae and/or Pythium spp. or by physiological disorders spread, and rootstocks to replace that of bottle gourd were sought. Based on the results of various trials, mainly on Cucurbita spp., the fusarium-wilt-resistant (f. sp. lagenariae) bottle gourd variety ‘Renshi’ was eventually released in the 1980s. Since then, fusarium-wilt-resistant bottle gourd rootstocks have been the main rootstocks used in Japan. The best choice for a rootstock cultivar is dependent on the production area, and many different rootstock species and cultivars are used for various conditions. The state of grafting of cucurbitaceous vegetables in Japan is briefly surveyed.