Fruit quality of tomato plants grafted on Solanum rootstocks

Fruit quality of the tomato plants (Lycopersicon esculentum Mill. cv. Momotaro) grafted on Solanum rootstocks was compared with that of tomato plant grafted on its own roots. The Solanum rootstocks used were S. sisymbriifolium, S. torvum and S. toxicarium; all of which are resistant to soil-born disease. The plants were grown under three levels of fertilizer, consisting of 15 N, 8 P2O5, 17 K2O. Fructose and glucose were detected in tomato fruits grafted on the four rootstock species, fructose content always exceeding that of glucose. The major organic acids were citric and malic;formic, oxalic, and pyrrolidone carboxylic acids were present at low concentrations. Regardless of the rootstocks, the amount of reducing sugars and organic acids in a fruit varied slightly with the cropping season, and the amount of fertilizer applied. The small difference in these fruit ingredients among tomato plants on the four rootstocks suggests that the fruit quality of the tomato plants grafted on other Solanum species is not different from that of tomato on its own roots.