2013 ASHS Annual Conference

Grafting of seedlings is an emerging technique for watermelon production in many countries. Due to higher costs, the use of grafted seedlings can only be recommended if it provides clear biological and economic benefits. Since rootstock performance is influenced by compatibility with the cultivar, by the existing disease pressure, and by the climate conditions, it is necessary to evaluate rootstocks with predominant cultivars to appraise possible benefits in a given area. With this objective, four seeded watermelons cultivars (Catira, Delta, Santa Amelia and 1414) and some combinations of these with two commercial rootstocks, Macis (Lagenaria ciseraria) and Marathon (Cucurbita maxima x Cucurbita moschata) were grown, in Curacaví (33º26’18”S, 71º01’31”W), Chile, in a soil that two years before had been used for watermelon production. Results showed a significantly greater fruit number (0.9 to 1.3 fruits/plant) and fruit mass (4.6 to 6.9 kg/fruit), which translated into higher marketable yields (38.2 to 89.2 ton/ha), in all grafted combinations compared to cultivars. All four cultivars were progressively affected by Fusarium wilt, while the grafted combinations were not visibly affected by the disease.  In terms of quality, no significant differences were found in pulp color (a = ± 24.2), firmness (11.8 N), and soluble solids content (10.1 ºBrix) between fruits from cultivars and from grafted combinations. The higher yields and larger fruits resulting from grafted plants would lead to a higher income that would largely offset the costs of grafting, and the technique appears highly recommendable for the given conditions.