Mapping Grapevine (Vitis vinifera L.) Water Status during the Season Using Carbon Isotope Ratio (δ~(13)C) as Ancillary Data

摘要

Vine water status is a major parameter for vine management because it affects both wine quality and yield. In order to optimize vineyard management and harvesting practices, it is necessary to characterize vineyard water status spatial variability. This work aims at establishing an empirical spatial model for stem water potential (Ψ_(Stem)) with ancillary data based on vine water status. Carbon isotope ratio (δ~(13)C) measured at harvest was selected as ancillary data because it reflects only the effect of vine water status variations integrated over the season and is not impacted by other factors such as vine nitrogen status. The proposed model was applied at the intrablock level. It is based on the spatial extrapolation of a Ψ_(Stem) value measured at a reference site using δ~(13)C values collected over the block. Measurements of Ψ_(Stem)and δ~(13)C were carried out over three consecutive years on 96 locations within the block. Ψ_(Stem) values obtained with a spatial model were more accurate than Ψ_(Stem) values obtained with a nonspatial model, indicating the relevancy of δ~(13)C values to account for spatial variability of vine water status. Results show that operational maps of vine water status can be obtained by means of a spatial model, in which δ~(13)C values from a previous season are used as ancillary data. Maps can be updated at any given time during the season by carrying out a limited number of Ψ_(Stem) measurements in selected locations. This model offers a tool to monitor vine water status and to implement management practices while considering vine water status intrablock variability.