Water status and must composition in grapevine cv. Chardonnay with different soils and topography and a mini meta‐analysis of the δ¹³C/water potentials correlation

BACKGROUND The measurement of carbon isotopic discrimination in grape sugars at harvest (δ 13 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. RESULTS This work, spanning over 3 years, performed in a hillslope toposequence in Burgundy, delineates the relationships between main soil properties (gravel amount, slope, texture) and the grapevine water status assessed by δ 13 C. The highest δ 13 C, indicating most severe water deficit, was recorded in gravelly soils on steep slopes. The amount of sugars and malic and tartaric acids was also related to δ 13 C. The relationship between δ 13 C and predawn leaf water potentials (Ψ pd ) was also investigated, because the absolute values of measured δ 13 C were lower than the values currently found in the literature. CONCLUSIONS A mini‐meta‐analysis was performed, which showed that the slope of the relationships between minimum Ψ pd and δ 13 C was stable across studies (a change of 1‰ in δ 13 C corresponded to a change of −0.2 MPa in the minimum Ψ pd ), while the intercept of the comparison δ 13 C/Ψ pd changed, probably because of genetic variations between varieties, or environmental differences.