The 2011 ASHS Annual Conference

Vegetable grafting is considered as a promising alternative to methyl bromide for controlling soil-borne diseases and improving crop yield. Grafting methods that determine efficiency of this technique have been continuously developed to meet different demands. In cucurbits, hole-insertion and one-cotyledon grafting are the most commonly used methods. When using hole-insertion method, both cotyledons of the rootstock plant are remained while grafting clips are not needed. In contrast, one-cotyledon method removes one cotyledon of the rootstock plant and the grafting union is supported by a grafting clip. Owing to incomplete removal of the apical meristem tissue from the rootstock plant, re-growth of rootstocks, also referred as rootstock suckers, is the major concern about these two methods. Cotyledon-devoid method that removes both cotyledons of rootstock plants has been proposed to eliminate the rootstock sucker problem. In this study, hole-insertion, one-cotyledon and cotyledon-devoid grafting methods were compared by grafting ‘Athena’ muskmelon (Cucurmis melo) onto three squash interspecific hybrid rootstocks including ‘Strong Tosa’, ‘Tetsukabuto’, and ‘Just’. In addition, a melon rootstock ‘Dinero’ was used. Non-grafted scions and rootstocks were used as controls. The results showed that the graft survival rate did not differ significantly among the three grafting methods. Rootstock suckers were developed in most plants grafted onto squash interspecific hybrid rootstocks when using hole-insertion and one-cotyledon methods. Interestingly, fewer suckers were observed with the ‘Dinero’ rootstock while sucker development was delayed. Number of true leaves, chlorophyll content, leaf area, aboveground biomass and root fresh weight were measured 22 days after grafting. Plants grafted with hole-insertion and one-cotyledon methods demonstrated significantly higher levels of aboveground biomass compared with plants grafted with cotyledon-devoid method and non-grafted scions. Furthermore, it indicated that grafting methods that maintain at least one cotyledon of the rootstock plant might help to produce grafted melon transplants with greater vigor. Root fresh weight was significantly lower in the grafted plants than that of non-grafted rootstock plants. This may be attributed to the influence of the scion on root development and/or the delay of root growth by the grafting and healing process.