Physiological comparison of ten grapevine varieties under severe water stress

Abstract

Global warming is representing a major challenge for Mediterranean agriculture. Improving irrigation and identifying or obtaining varieties tolerant to water scarcity are being constantly pursued. In this research we contrasted 5 varieties commonly cultivated in many wine-growing areas (Merlot, Garnacha, Shyraz, Malvasia and Muscat of Alexandria) with other five varieties mainly cultivated in Andalusia, Spain (Palomino fino, Rome, Doradilla, Tinto Velasco and Pedro Ximénez). Ten self-rooted clonal vines per variety were growth in pots for a vegetative season and some physiological parameters were evaluated at leaf level in three sampling dates: 1) at field capacity, 2) after two weeks once field capacity reduced to 15% and 3) five days after restoring field capacity (recovery). Also, biomass measurements were taken at point 2. In conditions of well-watered vines, in both points 1 and 3, Tinto Velasco showed the biggest intrinsic WUE (An/gs), followed by M. Alexandria and Garnacha. At 15% field capacity all varieties showed gs values close to zero, as well as An levels were very low, only Doradilla, Palomino fino and Merlot displayed a minimally appreciable photosynthetic activity so that these varieties had greater An/gs. In addition, Tinto Velasco seemed to be the most efficient variety at whole plant level, since it showed the smallest difference in biomass between well-watered and stressed vines relatively to difference in water consumed. If local and common varieties are considered as two separate groups, No significant difference were found neither at leaf nor at whole plant level. In all varieties, the severe hydric stress (Ψpd <-1.3MPa) did not allow a complete recovery of An, and gs after 5 days next to field capacity restoration.