Utilization of Membrane Bioreactor (MBR)-Treated Wastewater in Irrigation of Safflower (Carthamus tinctorius L.)...

This study evaluated the viability of utilizing membrane bioreactor (MBR)-treated wastewater for the irrigation of safflower (Carthamus tinctorius L., cv. Dinçer) under Mediterranean conditions. A field experiment was conducted in İzmir, Türkiye, from May 1st to August 13th, 2015, to assess the effects of four irrigation regimes under drip irrigation on plant growth and water use: weekly irrigation with MBR-treated wastewater (I1), weekly irrigation with freshwater (I2), phenological-stage irrigation with MBR-treated wastewater (I3), and no irrigation (I4). Seed yield, 1000-seed weight, oil content, evapotranspiration (ET), water use efficiency (WUE), and soil salinity were evaluated. Irrigation regimes significantly affected all yield-related parameters. The highest seed yield (363.5 kg da^-1) and oil yield (103.8 kg oil da^-1) were obtained under I1, followed closely by I2. No significant differences in yield were observed between I1 and I2, indicating that MBR-treated wastewater can serve as a viable alternative to freshwater for safflower irrigation. A notable saving in water use, accompanied with acceptable yield reductions, was achieved by phenological-stage irrigation (I3). The highest oil content (31.8%) was recorded under I4, indicating that water limitation increased oil concentration but reduced total yield. Soil electrical conductivity of the saturation extract (ECe) increased in the surface soil layers under MBR-treated wastewater irrigation (I1, I3); however, no adverse effects on plant growth were observed. Crop coefficient values (K_c) were higher than the standard FAO-56 values. It was concluded that MBR-treated wastewater can be utilized for safflower irrigation, if salinity and sodicity are regularly monitored and managed. Therefore, the adoption of this approach demonstrated to be a sustainable strategy for enhancing agricultural water reuse under water-scarce conditions.