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 toma to plant grafted on its own roots. The Solanum rootstocks used were S. sisymbriifolium, S. torvum and S. toxicarium; all of which are resist ant to soil-born disease. The plants were grown under three levels of fertilizer, consisting of 15 N, 8 P2O5, 17 K2O. Fructose and glucose w ere detected in tomato fruits grafted on the four rootstock species, f ructose content always exceeding that of glucose. The major organic ac ids were citric and malic;formic, oxalic, and pyrrolidone carboxylic a cids were present at low concentrations. Regardless of the rootstocks, the amount of reducing sugars and organic acids in a fruit varied sli ghtly 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 pla nts grafted on other Solanum species is not different from that of tom ato on its own roots.