Grapevines (Vitis vinifera L.) require precise irrigation to maintain yield and quality, and the increasing use of reclaimed desalinated water for fertigation raises concerns about the accumulation of reverse osmosis concentrate (ROC), a high-salinity byproduct with no sustainable disposal solution. This study explores the potential of ROC concentrates as a fertigation alternative, evaluating its effects on soil chemistry and vine adaptation. Using a lab-scale RO desalination system, we assessed grapevine responses under four irrigation treatments: tap water, tertiary-treated wastewater with low salinity and organic content, and the tertiary-treated wastewater desalination byproduct, two times (2X)- and four times- (4X) concentrate streams. By repurposing desalination by-products for viticulture, this study examines controlled salinity exposure as a means to determine vine adaptation thresholds and improve irrigation sustainability.
Irrigation with desalination-derived effluents’ concentrate significantly impacted soil chemistry and plant growth. Moderate salinity (2X Effluents) imposed the greatest stress, with the highest leachate EC in Barbera (7.35 mS/cm at 105DAT) and increased soil EC in both cultivars, leading to reduced root length density (RLD), root volume, root surface area, and root biomass. These reductions indicate that moderate salinity disrupts root development and nutrient acquisition, impairing plant vigor. In contrast, vines under 4X Effluents exhibited partial adaptation, showing improved root biomass, root volume, and shoot elongation compared to 2X Effluents. This suggests that grapevines can activate physiological responses to tolerate extreme salinity better than moderate salinity stress. Muscat exhibited greater resilience than Barbera, maintaining higher root and shoot biomass, RLD, and shoot elongation across treatments. The superior performance of Muscat suggests an inherent genetic advantage in salinity tolerance mechanisms compared to Barbera. However, 4X Effluents caused significant soil EC accumulation, particularly in Muscat (3.10 mS/cm), which raises concerns about long-term soil degradation and potential salt toxicity effects in vineyard soils.
Barbera and Muscat cultivars exhibited physiological adaptations under high salinity, with Muscat demonstrating greater resilience. However, prolonged irrigation with 4X Effluents may induce soil degradation, requiring optimized irrigation strategies to sustain vineyard productivity. Comprehensive elemental analysis of soil and leaf tissues is underway to determine ion accumulation patterns and their role in salinity tolerance, while metabolomic profiling of roots and leaves investigates biochemical pathways underlying adaptive stress responses.
