Is deficit irrigation with saline waters a viable alternative for winegrowers in semiarid areas?

Two of the main challenges of Mediterranean viticulture is low water quality and the risk of increasing concentrations of mineral salts in the root zone. This work was undertaken to study the impact of saline deficit irrigation on grape and wine phenolic composition, as well as on the sensory profile of the wines. The experiment was carried out during three consecutive years (2016-2018) in a commercial vineyard of cv. Monastrell (Vitis vinifera L.) grafted onto 1103P rootstock located in D.O. Jumilla (SE Spain). Three watering regimes were carried out: i) the control (Control): the vines were irrigated with water of standard quality, ii) Sulfate treatment (Sul): the vines were irrigated with saline water (Na2SO4 + MgSO4), and iii) Chloride treatment (Chl): the vines were irrigated with saline water (NaCl). The same amount of irrigation water was applied to all the treatments. The water electrical conductivity was 1.8 dS/m for Control and 5 dS/m for the saline treatments (Sul and Chl). Both the Sul and Chl treatments reduced the berry weight in all the study years compared to Control, although this difference was statistically significant in the last year only (p <= 0.05). No significant differences (p > 0.05) were observed in the grape quality parameters. However, the saline treatments slightly increased grape total soluble solids (TSS) in two out of the three study years compared to Control. Regarding the phenolic composition, no significant differences (p > 0.05) among treatments were found in grapes and wines. In general, the wines from vines irrigated with saline waters received the best scores by the panel in the sensory profile analysis. The use of saline waters could be employed in the case of water scarcity, as long as the vineyard is planted on a rootstock tolerant to salinity, such as 1103P, and the vineyard soil has a texture that favours leaching.

Automated summary

Low water quality and increasing mineral salt concentrations are two major challenges in Mediterranean viticulture. This study found that deficit irrigation with saline water can increase the soluble solids content in grapes, but has minimal impact on the phenolic composition of grapes and wines. However, wines produced from vines irrigated with saline water received the highest scores in sensory profile analysis. Therefore, in cases of water scarcity, the use of saline water for irrigation could be considered, provided that the vineyard is planted on a salt-tolerant rootstock and the soil texture promotes leaching.