Extreme weather conditions with prolonged dry periods and high temperature can severely influence grapevine physiology and morphology. Understanding the physiological and morphological responses of grapevines to water deficit is thus of utmost importance to modulate the appropriate plant development. The present study evaluates the effects of deficit irrigation (DI) on certain leaf characteristics of grapevine cv. ‘Italia’ cultivated on different rootstocks. DI had remarkable effects on the growth, morphology, tissue structure, water status and physiology of grapevine leaf. Response of the ‘Italiaʼ cultivar to DI depended on rootstock used. For example, leaf fresh weight of ‘Italiaʼ/5 BB under DI decreased by 15.2% in comparison to full irrigation (FI), whereas fresh weight values for ‘Italiaʼ/99 R and own-rooted vines under DI decreased 6.2 and 10.5%, respectively. Under FI treatment, stomatal conductance (g_s) reached values of 189.0 mmol m^-2 s^-1 in ‘Italiaʼ/5 BB, and 178.8 mmol m^-2 s^-1 in ‘Italiaʼ/99 R. The g_s values under DI condition were 178.1 and 164.0 mmol m^-2 s^-1 for the vines on 5 BB and 99 R respectively. Stomatal conductance decreased about 21.1, 13.8 and 10.2% in vines cultivated on 5 BB, 99 R and own root, respectively. In response to DI, leaf relative water content decreased about 9.4, 4.1 and 3.9% for ‘Italiaʼ/5 BB vines, own roots, and ‘Italiaʼ/99 R, respectively. Combined data over years revealed that the vines cultivated on 99 R displayed more tolerant leaf growth and physiology to drought in comparison to vines on 5 BB.

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