CHARACTERIZATION OF GRAPEVINE (VITIS VI-NIFERA L.) VARIETIES BASED ON DROUGHT INDUCED ACCLIMATION MECHANISMS

Different impacts of water deficiency on water relation and CO2 gas exchange in grapevine leaves were studied on two varieties belonging to two different ecogeographical groups. Fourteen-year-old vines of Vitis vinifera L. varieties 'Furmint` (autochthonous) and 'Sauvignon blanc' - were investigated in a non-irrigated vineyard on the Mecsek Hills in Hungary (latitude: 46 degrees 07' N; longitude: 18 degrees 17' E, 230 m a.s.l.). The varieties were studied under drought conditions and well-watered status in the year 2013. In practice, it was well known that drought tolerance of 'Furmint' is weaker compared to other varieties. According to pressure-volume analysis, osmotic potential at full turgor II100) in stressed 'Sauvignon Wane vines was lower compared to the control variants. Drought stress resulted in increasing 'epsilon' values ('epsilon' > 9 MPa) with 'Furmint', indicating decreased cell wall elasticity. Values of C-i and P-N showed a positive exponential correlation; C(i)values increased parallel with increasing net CO2 assimilation in well-watered and stressed vines. In each variety, intrinsic water use efficiency (WUEi) increased at reduced stomatal conductance. WUEi was significantly (P < 0.05) higher in drought stressed vines compared to the control variants in both varieties irrespective of the different ecogeographical origins.