Water stress and root hydraulic conductivity in grapevine grafted on different rootstocks

As demonstrated in many recent researches, grapevine rootstocks may affect vigor, water relations, mineral nutrition, fruit yield and quality of grapes. In order to better understand the influence of scion/rootstock combination on water use and drought resistance some water status characteristics were studied on grapevine vines grafted on different rootstocks. Old local grapevine variety Vitis vinifera 'Rebula' or 'Ribolla gialla' was grafted on eight rootstocks (196/17 Castel, 1103 Paulsen, 3309 Couderc, SO4, VI M, V M, Borner, 420 A, Rebula 6/28). Biometric characteristics (geometry, dry and fresh weight) and the root hydraulic conductivity (RHC) were measured during the trial. Midday stem water potential (SWP) was measured five times with a Scholander type pressure chamber. 3309 Couderc revealed to be water stress sensitive as reported in literature, while 1103 Paulsen which is described as high drought resistant did not match the expectations. After recovery some of the rootstocks showed an increase in root hydraulic conductivity, higher than in unstressed grapevines, thus suggesting that it is possible that the degree of suberisation could account for the differences in water transport through roots.