Potential use of treated wastewater for sustainable management of durum wheat under water-scarce environments

Water scarcity increasingly threatens agricultural sustainability, particularly in arid and semi-arid regions. Treated wastewater (TWW) represents a promising non-conventional water resource for irrigation, offering economic and environmental benefits while contributing to freshwater conservation. Despite concerns over anthropogenic contaminants, its physiological effects on key crops such as durum wheat remain underexplored. In this study, durum wheat (Triticum turgidum L. var. durum) was irrigated with TWW or freshwater (FW) and subjected to four levels of water stress (100%, 70%, 50%, and 30% of full irrigation), with or without the addition of a microbial consortium, to assess growth, physiological traits, and stress adaptation mechanisms. Overall, TWW produced vegetative, physiological, and productive performances comparable to or slightly higher than FW, without evidence of phytotoxicity. The microbial consortium showed variable effects, including occasional negative interactions under severe water deficit, highlighting the importance of soil–plant–microbe interactions and local pedo-climatic conditions. Controlled water stress reduced yield even at moderate levels, although gas exchange data indicate that moderate deficit irrigation (70%) could be physiologically tolerated, but did not translate into higher yield under pot conditions. These findings support the potential use of TWW for durum wheat cultivation under water-limited conditions and provide new insights into plant physiological responses under combined irrigation and microbial treatments. Further studies should evaluate these effects across multiple seasons and in open-field conditions.