Growth Development, Physiological Status and Water Footprint Assessment of Nursery Young Olive Trees (Olea europaea L. 'Konservolea') Irrigated with Urban Treated Wastewater

Application of urban treated wastewater (TWW) has been practiced globally as an alternative irrigation water source in areas where access to safe and abundant freshwater is limited. Water footprint (WF) has been employed over the last decades as a tool for the assessment of the sustainable management of water resources. In the present study, the suitability of TWW for the irrigation of nursery young olive trees (Olea europaea L. 'Konservolea'), one of the main table olive cultivars in Greece, the second global table olive exporter, was tested and compared to tap water irrigation and application of zeolite on soil. Plant growth and physiological parameters and stress indicators were measured. Additionally, a WF assessment was performed, distinguishing TWW from freshwater (blue water) resources in order to examine the possibility of minimizing the environmental impact through the limitation of freshwater use. Plants irrigated with TWW performed better in most of the growth and physiological parameters measured compared to the other treatments. Stress indicators revealed that TWW did not induce any additional stress. TWW could be used as an irrigation water source for young olive trees for at least a short period during their growth as a safe and sustainable alternate of blue water resources. Additionally, the WF assessment showed that the application of TWW could be a significant blue water saving measure.