Carbon isotope ratio of whole berries as an estimator of plant water status in grapevine (Vitis vinifera L.) cv. 'Tempranillo'

► We evaluated the usefulness of whole berry δ13C as an integrator of plant water status in grapevine and determined its temporal sensitivity. ► The moment at which water deficit occurs conditioned remarkably the response observed. ► The sensitivity was higher at two periods critical for sugar accumulation: veraison and 4-6 weeks before harvest. ► This fact has to be considered when interpreting δ13C values.