GRAFTING, A USEFUL TECHNIQUE FOR IMPROVING SALINITY TOLERANCE OF TOMATO?

     The use of grafted plants in vegetable crop production is still rare compared to the use of grafting for tree crops. However, this technique is now being expanded greatly in order to reduce infections caused by pathogens, to increase resistance to drought and to enhance nutrient uptake. Although there is little information on the translocation of solutes from scion to rootstock in vegetables, it has been reported that some permanent changes take place in the scion, induced by the solutes from the rootstock. In most of the studies with trees, root genotype was more important than shoot genotype with respect to yield under stress conditions, since the vigorous root system of a rootstock is often capable of absorbing water and nutrients more efficiently than scion roots. In our experiments, we have used commercial tomato seedlings, grafted on a rootstock by the ‘tongue approach grafting’ method and grown in a crop chamber. The response of the grafted plants to salt exposure (60 mmol L^-1 NaCl) was compared with that of ungrafted plants. Under non-saline conditions, water uptake was decreased by grafting, but when salinity was imposed, no significant difference in water uptake was observed between grafted and ungrafted plants. These results, studied in the light of aquaporin involvement, in both roots and leaves and related to the Na+ and Cl- accumulation in leaves, lead us to conclude that the grafting technique could be a useful tool for increasing the tolerance of plants to salinity.

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