Effects of wastewater applied with discrete irrigation techniques on strawberry plants' productivity and the safety, quality characteristics and antioxidant capacity of fruits

Water scarcity renders wastewater (WW) reuse for irrigation an increasingly common practice worldwide. Comprehensive guidelines and criteria have been established to secure the safety of WW irrigation, especially for food crops or crops that are eaten raw. The aim of this short-term study was to assess the impacts of strawberry crop irrigation with tertiary treated wastewater (WW) using common irrigation techniques (Drip, sprinkler, drip under plastic mulch), as compared to potable water (PW) irrigation, on strawberry fruits' quality and safety, and on crops' productivity. The impacts on fruits' weight and marketability, as well as on fruits' taste (soluble solids, titratable acidity and soluble solids/titratable acidity ratio), antioxidant capacity (ascorbic acid concentration, FRAP, total phenolics and total anthocyanin content), heavy metal content (Cu, Zn, Mn, Co, Ni) and microbial contamination (total coliform, E. coli, Salmonella spp., Listeria spp), were evaluated. The results revealed that WW irrigation did not significantly affect the fruits' marketability, taste and antioxidant capacity, as well as the heavy metal content, in comparison to controlled irrigation, regardless of the irrigation technique applied. Fruits heavy metal content was found to be below the maximum permissible levels (MPLs) set for fruit safety, whereas no microbiological contamination (total coliform, E. coli, Salmonella spp., Listeria spp.) of fruits was found in all irrigation water treatments. Overall, the results obtained with regard to the parameters examined highlight the potential for the reuse of the advanced tertiary treated effluent of good quality as a valid alternative for the irrigation of strawberry crops, even with sprinklers. However, further long-term studies are needed in order for such a practice to be regulated.