Impact of moderate water deficit on grape quality potential on Pinot Noir in Champagne (France)

Abstract

Context and purpose of the study – Environmental factors like soil and climate influence grape quality potential. Their impact is often mediated through vine water and nitrogen status. Depending on the color of the grapes (red or white) and the type of wine produced, the desired level of vine water and nitrogen status for optimum wine quality is different. Little investigation has been carried out concerning these factors and their potential influence on sparkling wine quality on two vintages. In this study vine water and nitrogen status were assessed at a very high density and related to grape composition and berry weight. Through statistical analyses, the major factors driving grape quality potential on Pinot noir in Champagne were highlighted.

Material and methods – High quality Champagne potential was related to particular grape composition. On 25 hectares planted with Pinot noir, grape samples were taken following a very high density grid (10 samples / ha). One sample is composed of 200 berries taken on 10 vines. On these samples, vine water status was assessed by measuring δ13C in grape juice and vine nitrogen status by measuring NH4+ in must. Berry weight, grape sugar, total acidity, malate and pH were also measured. Berry weight was recorded at each sampling location while yield was measured at a lower spatial resolution (the parcel level). These measures have been carried out on two vintages (2017 and 2018) and on 4 locations known to produce different quality levels of Champagne.

Results – Quality level of Champagne was positively related to technological maturity of Pinot noir. Following, malate and sugar/total acidity ratio (S/TA) were considered as a proxy for grape quality potential. A vintage effect was highlighted, the higher level of water deficit in 2018 increased the level of maturity compared to 2017. There is also a location effect, Tauxières Nord and Sud have a lower level of maturity even if Tauxières Sud is more constraint in 2018 than the other locations.
Water deficit plays an important role on maturity of Pinot noir in our study with a strong significant relation with malate and a significant link more or less important depending on vintage with pH, S/TA ratio and berry weight.
The effect of vine nitrogen status on maturity is more complex with no clear correlations during the vintages studied.
Berry weight is positively correlated to water deficit (δ13C) in a dry vintage (2018) and to vine nitrogen status (must NH4+) in a vintage characterized by lower water deficit (2017). A yield effect has been identified particular on S/TA ratio.
When Pinot noir vines face water deficits in Champagne, maturity is improved. It should be noted that due to capillary water movements in the limestone soils, water deficits are rarely severe. In our study water deficits ranged from non-existent to moderate. Water deficit improved grape quality potential for sparkling wines produced from Pinot noir in this study. More investigations are needed to confirm these results in other vintages and on a wider range of soil types.