Evaluation of Intra-Cultivar Variability in the Drought-Response Strategy of Vitis vinifera L. cv. País from Different Geographic Provenances

Le résumé fourni par la source

Water scarcity increasingly threatens viticulture, but the drought-response strategy of patrimonial cultivars such as País remains poorly characterized. This study evaluated intra-cultivar variation in drought response among País plants from Arica, Huasco, and Limarí, using Cabernet Franc as a reference, under semi-controlled pot conditions during a five-week dry-down followed by rewatering. Relative pot water content, stem water potential, and stomatal conductance were monitored repeatedly, and provenance-specific stomatal thresholds (P12, P50, and P88) were estimated from nonlinear vulnerability curves. Water deficit caused a progressive decline in pot water content, stem water potential, and stomatal conductance in all materials. Cabernet Franc maintained the highest maximum stomatal conductance, whereas País showed a more conservative stomatal pattern. Provenance differences within País were clearest at P50: Huasco reached 50% stomatal reduction at more negative stem water potentials than Arica and Limarí, while P12 and P88 largely overlapped. After rewatering, stem water potential recovered more rapidly than stomatal conductance, with Arica and Limarí showing the strongest hydraulic recovery. These results demonstrate physiologically relevant intra-cultivar variation in País and indicate that drought-response strategy in this cultivar is not explained by source-site aridity alone, but by provenance-specific regulation of stomatal decline and recovery.

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