Evaluation of the adaptation of Palomino Fino clones based on their physiological response

Genetic diversity within grapevine cultivars is a fundamental resource for varietal improvement and adaptation to cultivation requirements. Clonal selection is currently the most widely accepted method of improving wine grape varieties and relies on the identification of somatic variants exhibiting desirable traits. Palomino Fino is the most extensively cultivated autochthonous grapevine variety in Andalusia, traditionally used in the production of Sherry wines. Despite the existence of 28 officially recognized Palomino Fino clones, their physiological behavior has not been recently studied. In this context, this research work aimed to evaluate ten certified Palomino Fino clones (coded from 1 to 10) through measurements of photosynthetic rate (AN), leaf stomatal conductance (gs), intrinsic water use efficiency (WUEi), and effective quantum yield of photosystem II (PhiPSII). Significant intravarietal variability was observed in all parameters. Clones 7 and 8 maintained higher values of AN and gs throughout most of the season, along with elevated PhiPSII values, indicating greater physiological performance and adaptability. Conversely, clones 1, 2, 3, and 10 showed generally lower photosynthetic rates, meanwhile clones 1 and 10 exhibited higher WUEi, suggesting a potential advantage under water-limited conditions. These results highlight the value of physiological characterization in guiding clonal selection for vineyard adaptation in the context of climate change.