Assessing Spatial Variability of Grape Skin Flavonoids at the Vineyard Scale Based on Plant Water Status Mapping

Abstract

Plant water stress affects grape (Vitis vinifera L. cv. Cabernet Sauvignon) berry composition and is variable in space due to variations in the physical environment at the growing site. We monitored the natural variability of grapevine water stress by stem water potential (Ψ) and leaf gas exchange in an equi-distant grid in a commercial vineyard. Spatial differences were measured and related to topographical variation by modeling. Geospatial analysis and clustering allowed researchers to differentiate the vineyard block into two distinct zones having severe and moderate water stress where it varied by 0.2 MPa. Differences in stem water potential affected stomatal conductance, net carbon assimilation, and intrinsic water use efficiency that were different in all measurement dates. The two zones were selectively sampled at harvest for measurements of berry chemistry. The water status zones did not affect berry mass or yield per vine. Significant difference in total soluble solids was observed (3.56 Brix), and in titratable acidity, thus indicating a direct effect of water stress on ripening acceleration. Berry skin flavonol and anthocyanin composition and concentration were measured by C18 reversed-phased high-performance liquid chromatography (HPLC). The anthocyanins were most affected by the two water stress zones. The dihydroxylated anthocyanins were more affected than trihydroxylated; therefore, the ratio of the two forms increased. Flavonols were different in total amounts, but hydroxylation patterns were not affected. Proanthocyanidin isolates were characterized by acid catalysis in the presence of excess phloroglucinol followed by reversed-phase HPLC. Proanthocyanidins showed the least significant difference, although (+)-catechin terminal subunits were important predictors in a partial least square model used to summarize the multivariate relationships, predicting Ψ or the management zone. The results provide fundamental information on vineyard water status to discriminate harvest or direction to vineyard operators to modify irrigation management to equilibrate berry composition at harvest.

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

“…This work also shows that great variations in grapevine water status are observable within short distances in vineyards, as already observed in previous studies . This variability can have important consequences on must composition, sugars and acids, and the effect of water status on must composition has already been shown in many other studies .…”

“…Eventually, it will be important to design experiments in order to provide additional validation tests to demonstrate the efficiency of the models, for example comparing the predictions to other measurements of the same biological phenomenon, such as machine-learning predictions of leaf water potentials to measured 13 C. 26 This work also shows that great variations in grapevine water status are observable within short distances in vineyards, as already observed in previous studies. 3,4,51 This variability can have important consequences on must composition, sugars and acids, and the effect of water status on must composition has already been shown in many other studies. 6, 10,16,51 This study report a backward approach, explaining the amount of water deficit from differences in must composition at harvest, which was chosen as the date of the commercial harvest in that field.…”

“…3,4,51 This variability can have important consequences on must composition, sugars and acids, and the effect of water status on must composition has already been shown in many other studies. 6, 10,16,51 This study report a backward approach, explaining the amount of water deficit from differences in must composition at harvest, which was chosen as the date of the commercial harvest in that field. Because of the sampling design, it cannot be excluded that differences in must composition were related to a delay in ripening, suggesting that in all growing sites similar must composition could be achieved by selective harvest.…”

“…This work also shows that great variations in grapevine water status are observable within short distances in vineyards, as already observed in previous studies . This variability can have important consequences on must composition, sugars and acids, and the effect of water status on must composition has already been shown in many other studies . This study report a backward approach, explaining the amount of water deficit from differences in must composition at harvest, which was chosen as the date of the commercial harvest in that field.…”

“…This study report a backward approach, explaining the amount of water deficit from differences in must composition at harvest, which was chosen as the date of the commercial harvest in that field. Because of the sampling design, it cannot be excluded that differences in must composition were related to a delay in ripening, suggesting that in all growing sites similar must composition could be achieved by selective harvest . However, in Burgundy the harvest period is frequently shortened by bad weather or eventually by Botrytis cinerea Pers.…”