The use of δ¹³C as an indicator of water use efficiency for the selection of drought tolerant grapevine varieties

Abstract

In the context of climate change with increasing evaporative demand, understanding the water use behavior of different grapevine cultivars is of critical importance. Carbon isotope discrimination (δ¹³C) measurements in wine provide a precise and integrated assessment of the water status of the vines during the sugar accumulation period in grape berries. When collected over multiple vintages on different cultivars, δ¹³C measurements can also provide insights into the effects of genotype on water use efficiency. More specifically, cultivars with more negative values of δ¹³C (indicating later stomatal regulation) in non-limiting conditions could reveal higher vulnerability to drought ^[1]. Thus, selecting varieties with less negative δ¹³C values in non-limiting conditions could be a potential lever for adaptation to climate change.

A 2-hectare parcel was planted with 84 red and white cultivars in 2013, in the Haut Médoc wine region (Bordeaux, France) within a commercial wine-growing estate. Among those 84 cultivars, 7 were vinified over 5 vintages, 19 over 4 vintages and 24 over 3 vintages, resulting in a dataset of δ¹³C of 50 different cultivars over 3 to 5 vintages. The varieties included all the traditional Bordeaux varieties, some common varieties of Spain and Portugal, as well as other widely planted French varieties.

The vintage effect was clearly shown in the analyses, with the wettest vintages expressing more negative values of δ¹³C than drier vintages. δ¹³C values were also significantly different depending on the cultivar, allowing for a characterization of the 50 cultivars for their water use efficiency in limiting and non-limiting conditions. These results provide insights in the strategy of the cultivar’s water use and could help identifying potential drought tolerant varieties.

1. Plantevin, M., Gowdy, M., Destrac-Irvine, A., Marguerit, E., Gambetta, G. A., & van Leeuwen, C. (2022). Using δ¹³C and hydroscapes for discriminating cultivar specific drought responses. OENO One, 56(2), 239–250. https://doi.org/10.20870/oeno-one.2022.56.2.5434