Grafting is widely established in agriculture and provides practical advantages for vegetable production. We investigated physiological differences between the grafted combinations of Dutch (Starbuck and Maxifort) and Japanese (Reiyo, Receive and Magnet) tomato cultivars. Plants were grown hydroponically until the flowers on the first truss bloomed, and the following parameters were measured: fresh weight of the aerial parts, root surface area, root permeability (by using a pressure chamber),

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... d water potential of exudates (by using an isopiestic psychrometer). The Starbuck/Maxifort combination had higher values of the aerial part weight, root surface area, and root permeability than Reiyo/Receive, whereas Reiyo/Maxifort tended to have higher values of these parameters than Reiyo/Receive and Reiyo/Magnet. Maxifort had a significantly larger root surface area than Receive, but root permeability was not significantly different. InReiyo/Maxifort and Starbuck/Receive, these parameters were not significantly different except for a single comparison of root permeability. Thus, root permeability and root surface area may depend not only on the rootstock but be also affected by scion in grafted plants. Water potential of exudates was similar in most combinations and experiments. This shows that three rootstock cultivars provided similar nutrient concentrations even with different scions.