Soil and topography effects on water status and must composition of chardonnay in burgundy & a mini meta‐analysis of the δ 13C/water potentials correlation

Abstract

Context and purpose of the study: The measurement of carbon isotopic discrimination in grape sugars 13 at harvest (δ C) is an integrated assessment of water status during ripening. It is an efficient alternative to assess variability in the field and discriminate between management zones in precision viticulture, but further work is needed to completely understand the signal.

Material and methods: This work, spanning over 3 years, performed in in 8 different plots in a hillslope toposequence in Burgundy, delineates the relationships between main soil properties (gravel amount, slope, texture) and the grapevine water status assessed by δ13C and predawn leaf water potentials (Ψpd). Brix, tartaric and malic acids were also measured.

Results: The highest δ13C, indicating most severe water deficit, was recorded in gravelly soils on steep 13 slopes. The amount of sugars and malic and tartaric acids was also related to δ C. The relationship between δ 13C and Ψpd was also investigated, because the absolute values of measured δ 13C were lower than the values currently found in the literature. A mini‐meta‐analysis was performed, which 13 showed that the slope of the relationships between minimum Ψpd and δ C was stable across studies (a 13 change of 1‰ in δ C corresponded to a change of −0.2 MPa in the minimum Ψpd), while the intercept of the comparison δ 13C/Ψpd changed, probably because of genetic variations between varieties, or environmental differences.