Grafting Tomato Cultivars for Soil Borne Disease Suppression and Plant Growth and Yield Improvement

Soil borne fungal diseases are among the most damaging diseases of tomato in Tunisia. Among them, Fusarium wilt (FW) caused by Fusarium oxysporum f. sp. lycopersici (FOL) races 1 and 2, Fusarium Crown and Root Rot (FCRR) incited by F. oxysporum f. sp. radicis lycopersici, and Verticillium wilt (VW) due to Verticillium dahliae (Vd) races 1 and 2 are of particular concern. In the current study, the grafting of three scion tomato cultivars (cvs. Kawthar, Amal and Malinche) onto the interspecific hybrid rootstock Maxifort was evaluated for diseases management and plant growth and yield improvement. Under artificial inoculation conditions, the present study demonstrates that the plant response to the tested pathogens (Vd races 1 and 2, FOL races 1 and 2 and FORL) used for inoculation differed according to the tomato cultivars used, the grafting treatment and their interactions. Overall, grafting was shown to be effective in significantly reducing disease severity, estimated via the relative vascular discoloration extent (RVDE), by 24%, and enhancing root and stem fresh weights and yield by 18%, 30% and 17%, respectively, compared to non-grafted controls. Under natural greenhouse conditions, disease severity was statistically comparable on grafted and non-grafted cvs. Kawthar and Malinche, plants. However, grafting cv. Amal plants have significantly reduced, by 61%, the RVDE as compared to non-grafted ones. Root fresh weight noted on Maxifort-grafted cvs. Kawthar, Amal and Malinche plants was significantly enhanced by 32, 59 and 55%, relative to non-grafted ones. Plants grafted onto Maxifort rootstock had produced 63% higher total yield than the non-grafted control. As assessed by comparative disease symptoms and plant growth and yield response, grafting tomato on the rootstock Maxifort have could be implemented in an integrated disease management with other soil disinfection methods for reducing soil borne populations in the soil.