Response of grapevine to irrigation with treated wastewater

Mestrado em Viticultura e Enologia - Instituto Superior de Agronomia / Faculdade de Ciências. Universidade do PortoClimate change, population growth, industry expansion and increasing water demand in agriculture are pressuring water resources in dry, warm-climate regions, such as Mediterranean Europe. The aim of this study was to evaluate the possibility of using treated wastewater (TWW) for vineyard irrigation, as a strategy to maintain grapevine's water status within acceptable levels, while contributing to decrease the pressure on natural water resources. To achieve this goal, the effects of TWW and conventional water (CW) on grapevine and soil were compared after two years of irrigation. TWW appears to have had a significant impact on soil salinity, with TWW irrigated soil having a 10% higher salinity (VIC) than the CW irrigated one. Concerning grapevine growth rate and ecophysiology, shoot length of TWW irrigated vines was significantly lower (15%), though there were generally no differences in phenology and reflectance indexes (PRI and NDVI) between treatments. In one measurement during summer peak, though, NDVI values were significantly lower for TWW irrigated vines. Also during summer peak, berries of TWW irrigated vines were significantly darker and greener, and had higher total acidity than CW irrigated vines. Canopy traits such as exposed leaf area, total leaf area and leaf layer number did not differ between treatments, and the same occurred for grape and wood yield, suggesting that TWW had no impact on vine balance and yield. It is crucial to continue exploring the use of TWW for irrigation as an answer to drought and water scarcity, while studying its effects on crops and soil within wider time periods, to scout for long-term impacts of this practiceN/