Using reclaimed water to irrigate a Mediterranean vineyard: isotopic insights into the depth of water uptake and its physiological and agronomical effects

Abstract

In many traditional wine-growing regions of Europe, most of the vineyards remain rainfed. However, increasingly hot and dry conditions are leading winegrowers to consider irrigation as an option to ensure the viability of grape production and the wine industry. Unfortunately, not all regions have a readily accessible freshwater supply for irrigation. Even when access to water is possible, this can be restricted during periods of prolonged drought. In this context, the use of reclaimed water appears to be an attractive solution allowing to irrigate regions with limited freshwater resources. Previous studies (Mendoza-Espinosa et al., 2008) in vineyards have demonstrated that the quality of reclaimed water is safe and effective. Still, reclaimed water increases the soil’s electrical conductivity and the content of certain cations (De las Heras & Mañas, 2020). To adapt the use of reclaimed water to different agronomical situations, we need to understand its effects on soil physics and plant water relations. In this communication, we will expose the results of a field trial in a vineyard (cv. Macabeu, grafted onto 140 Ruggieri) in Valls (Catalonia, Spain) irrigated with reclaimed water coming from a municipal wastewater treatment plant. We compared soil water dynamics, grapevine ecophysiology, and agronomical performance in three different irrigation treatments and a control, rainfed treatment. We used the isotopic composition of water in oxygen and hydrogen to track soil water movement and infer the depth profile of plant water uptake (Barbeta et al., 2018). Marked differences in the depth of plant water uptake were found between rainfed and irrigated vines, but those also varied depending on the meteorological conditions and the irrigation regime. The electrical conductivity of the irrigation water ranged between 1.2 and 1.3 dS/m, which may slightly affect the capacity of roots to extract water, the physiological status of the plant and vine performance on the long-term (Shani & Ben-Gal, 2005). Indeed, irrigated vines presented a stronger seasonal decline of the osmotic potential at full turgor and of the water potential at turgor loss point, compared to the rainfed vines. Finally, we evaluated the yield, must quality, and vegetative growth of vines of the different treatments. Our results should allow a more informed deployment of reclaimed water as a source for irrigation in Mediterranean vineyards through a detailed understanding of soil processes, ecophysiological mechanisms and agronomical performance.

References

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De las Heras, J., & Mañas, P. (2020). Reclaimed Wastewater to Irrigate Olive Groves and Vineyards: Effects on Soil Properties. Agronomy, 10(5), 649. https://doi.org/10.3390/agronomy10050649

Mendoza-Espinosa, L., Cabello-Pasini, A., Macias Carranza, V., Daessle, L., Orozco-Borbón, M., & Quintanilla-Montoya, A. (2008). The effect of reclaimed wastewater on the quality and growth of grapevines. Water Science & Technology, 57(9), 1445–1450. https://doi.org/10.2166/wst.2008.242

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