Salinity response in melon scions as affected by grafting

Grafted plants are often more tolerant to stresses such as drought and salinity than non-grafted controls. The wide literature available usually attributes the increased tolerance to different elements, such as ion exclusion or accumulation within the rootstock, impaired stress signaling, improved water uptake and exchanges, or even the increased vigor attributable to the grafting adaptation itself. Indeed, as far as salt tolerance goes, a rootstock effect, a scion effect and a rootstock x scion effect may be generally observed. In order to dissect the differential elements involved in the salt response in grafted melon, salt stress was imposed on several rootstock/scion combinations in three experiments under different environmental conditions and locations across Europe (Izmir, Turkey; Budapest, Hungary; Bologna, Italy). In all experiments the rootstock used was an interspecific squash hybrid (Cucurbita maxima x Cucurbita moschata), combined with different Cantaloupe (Cucumis melo var. cantalupensis) cultivars. Self-grafted and non-grafted controls were included in the trials in order to evidence graftingrelated effects. Plants exposed to salinity (0, 40, and 80 mM NaCl), were monitored in terms of physiological (leaf gas exchanges, porometry and overall transpiration), biochemical (ion accumulation and osmolytes), and morphological (root and leaf features) adaptations.