Salinity Responses of Grafted Grapevines: Effects of Scion and Rootstock Genotypes

Two-year-old Sultana and Mke vines (Vitis vinifera L.) grafted onto Rupestris du Lot (Vitis rupestris Scheele) and 110 R (Vitis berlandieri Vitis rupestris) were grown in soil, sand, sphagnum peat and farmyard manure mixture (2:1:1:1 v/v) irrigated with 0.3, 2.7 and 5.45 dS m-1 NaCl solutions for a period of 60 days. Biomass accumulation, relative chlorophyll content, leaf water potential, stomatal conductance and transpiration were significantly reduced by salinity in all graft combinations. The inhibiting effect of salinity on growth varied according to the characteristics of the scion genotype and the level of salinity. The results imply the predominance of the scion genotype in determining variation in the leaf-level physiological characteristics of grafted vines because stomatal conductance and transpiration were higher in Sultana than in Mke at the same leaf water potential and the level of salinity, regardless of the rootstock genotype. NaCl treatments did not affect leaf Cu concentration while inducing significant Na, K, Ca, N, P, Mg, Fe, Mn and Zn elevations in the leaves of all scion/rootstock combinations. While salinity caused an increase in N content and a decrease in K content in the roots of all graft combinations, it had no influence on Ca, P, Cu and Zn concentrations. In contrast to the Sultana grafted vines, NaCl salinity led to a decrease in Mg, Fe and Mn concentrations in the roots of Mke grafted vines. Nevertheless, ion accumulation in leaves and roots of grafted vines under saline or non-saline conditions was controlled predominantly by the genotype of the scion. In response to salinity, Sultana grafts accumulated higher amounts of ions in their leaves than in their roots. However, in Mke, higher ion concentrations were seen in the roots. Therefore, the increase in the transport of inorganic ions up to the leaves seems to be the major component of osmotic adjustment in salt-stressed Sultana vines.