Long-term impact of deficit irrigation on the physiology and growth of grapevine cv. ‘prima’ grafted on various rootstocks

Testing the globally popular grapevine rootstocks for affinity with new grape cultivars or tolerance potential to stress factors like drought is essential for districts where supplemental irrigation is more frequently needed due to the pressures of a global climate change. In this study, a seasonal evaluation of leaf gas exchange, leaf temperature, leaf greenness (chlorophyll content prediction) and vegetative development of Vitis vinifera L. cv. ‘Prima’ grafted to different rootstock genotypes having great variability in drought tolerance, were investigated. The experiment was conducted in a controlled experimental glasshouse on two-year-old soilless grown ‘Prima’ vines grafted on nine rootstocks [44-53 M, 5 BB, 140 Ru, Ramsey (Syn. Salt Creek), 99 R, Saint George (Syn. Rupestris du Lot), 41 B, 1613 C and 420 A]. A long-term deficit irrigation (DI) was imposed before bud break by reducing water supply to 40% of field capacity derived from concurrent measurements of water content of growth medium and maintained until the end of vegetation period. The rootstocks significantly modulated the physiology and vegetative growth of the scion cultivar in varying degrees according to their genetic features. Among them, 140 Ru rootstock found to be more prominent in terms of mitigating the adverse effect of water deficit on physiology and growth of the scion genotype ‘Prima’ as there were no significant difference between deficit and full irrigation treatments for most of parameters investigated. In general, the ‘Prima’ scion performed better when the rootstocks coming from V. berlandieri × V. rupestris pedigree rather than the others including V. berlendieri × V. riparia.