Composition of irrigated red and white Grenache grapes under different soil-management systems in semi-arid Mediterranean conditions (2025 vintage)

Abstract

Conventional vineyard tillage and herbicide use can negatively affect soil quality and ecosystems, particularly under Mediterranean climate-change conditions. Cover crops may reduce soil compaction and environmental impact. This study evaluated the effect of soil management on the composition of irrigated Red Grenache and White Grenache grapes under semi-arid conditions. The 2025 trial compared conventional tillage with a sown legume cover crop (Medicago spp. and Trifolium spp.) in experimental vineyards managed with regulated deficit irrigation at 30 % ETo from pea-size berries until harvest. Berry weight, soluble solids, total acidity, pH, malic acid, and tartaric acid were monitored; total polyphenols and anthocyanins were also analysed in Red Grenache. Ripening followed a normal physiological pattern under both systems. Cover cropping tended to reduce berry weight, soluble solids, pH and malic acid, while increasing tartaric acid. Yield differences were not significant, although cover-cropped plots tended to produce less. At harvest, soluble solids and malic acid tended to be lower under cover cropping, with cultivar-dependent intensity. Red Grenache also showed significantly lower anthocyanin content. The response was therefore cultivar-specific: cover cropping modified sugar accumulation and reduced soluble solids and anthocyanins in Red Grenache, whereas White Grenache showed no relevant differences from conventional tillage. Additional vintages are required to confirm these trends.

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Acknowledgements

This work is part of R&D&I project PID2023-1469110R-C51, funded by MCIN/AEI/10.13039/501100011033 and FEDER, and Operational Group project VIÑA-RAICES, funded by MAPA and FEDER. The authors also acknowledge research group AGA001 and the Regional Government of Extremadura.