Grafted plants of vegetable crops have gradually increased in the last years in Japan, Korea, and Mediterranean basin countries (Spain, Italy, Tunisia). Initially, this technology has been proposed control soilborne diseases. In addition, grafted plants have showed other advantages such as the improvement of tolerance to environmental stresses, the increasing of nutrient and water use efficiency and, in some cases, the improvement of crop productivity. Throughout this review, focused on Cucurbitaceae (watermelon, melon, cucumber) and Solanaceae (tomato, pepper, eggplant) species, we have examined the genetic and physiological aspects linked to resistance or tolerance to soilborne diseases and tolerance to abiotic stresses (salinity, root hypoxia, low and high temperature) of grafted plants, as well as to the plant productivity and fruit quality. As an alternative to geodisinfestation by methyl bromide, the choice of appropriate rootstocks represents one of the most important factors to be considered in the control of the main soilborne pathogens: some specific races of Fusarium oxysporum (melon, watermelon, cucumber), Verticillium dahliae (eggplant, pepper), Monosporascus cannonballus (melon, watermelon), Meloidogyne spp. (eggplant, pepper), Didymella bryoniae (watermelon, melon), Pyrenochaeta lycopersici (tomato). Improvement in salt tolerance by grafting in tomato and melon was related to the capability of rootstocks to avoid physiological damages caused by excessive accumulation of toxic ions (Na+ and/or Cl-) in shoots, including the exclusion and/or reduction of absorption of Na+ and/or Cl- by the roots. However, the salt tolerance is not influenced only by the rootstock but also by the scion. Grafting tomato and melon on tolerant rootstocks to low soil temperatures has been proposed as an useful strategy to improve crop performance. Recent studies have showed that, in tomato, is possible to rise the tolerance to high temperature by grafting on tomato rootstocks tolerant to this abiotic stress. Grafting, often realised between plants of different species, can influence vigour, yield and the fruit qualitative characteristics (soluble sugar content, acidity, shape and fruit weight, alkaloid content and antioxidant compounds). The crop performance of grafted plants has often been attributed to the rootstock-scion compatibility and to the influence of rootstock on water and nutrient uptake as well as to the endogenous-hormone status of plant. However, the frame is very complex because the response of grafted vegetable plants changes in relation to the crops, the cultivars, the scion/rootstock combinations, the environmental conditions, and the cultural practices.
Keywords: rootstock, Solanaceae, Cucurbitaceae, biotic stress, abiotic stress