Response of plant yield and leaf ion contents to salinity in grafted tomato plants

Although many studies have been carried out to determine the response of grafted trees to saline conditions very few have used the grafting techniques in vegetables with this objective. In this study, scions of the Lycopersicon esculentum cv Moneymaker (salt-sensitive) were grafted onto rootstock Lycopersicon esculentum cv Pera (salt-tolerant), and compared with Moneymaker (MM) grafted on its own root (control). In the survival grafted plants, more than 90 % success was achieved. After the graft had established, plants were transplanted to the greenhouse. The salt treatment (50 mM NaCl) was added to irrigation water from 10 days after the transplant to the end of the experiment, and the EC of the irrigation solution was 6.5 dS m(-1). Fruit yield was determined after several harvests, and Na+ and K+ concentrations were measured at the end of the experiment in completely developed leaves. The fruit yield was significantly greater in grafted plants of MM onto Pera than in self-grafted plants. Since the fruit weight were very similar in both grafted combinations, the yield increase in MM/Pera, with respect to MM/MM, was mainly due to a higher fruit number. There were also significant differences between the Na+ and K+ concentrations in the leaves of the salt-treated grafted plants, with the MM/Pera leaves accumulating more Na+ and K+ than MM/MM ones. These preliminary results suggest that root characteristics determine, at least partially, the salinity response of tomato and, consequently, the grafting may be a valid strategy for the tomato culture in saline conditions.