Impact of Irrigation Using Water Containing CuO and ZnO Nanoparticles on Spinach oleracea Grown in Soil Media

Wastewater reuse is an important adaptation option for mitigating water stress in rapidly growing urban centers. Reuse potential of nanoparticles (NPs) contaminated wastewater for irrigation of Spinacia oleracea grown in soil media were assessed in this study. Irrigation of plant were done with water containing CuO and ZnO NPs as single compound and in binary mixture (10, 100, 1000 mg/L) till 11 weeks. At 1000 mg/L, reduction in root length: 16 %, 12 % and 18 %, shoot length: 22 %, 16 % and 27 %, total weight 37 %, 27 % and 45 %, chlorophyll: 18 %, 7 % and 29 % and carotenoids: 46 %, 33 % and 54 % were found for CuO NPs, ZnO NPs and binary mixture of NPs respectively. Uptake values were found to be 5.65 ± 0.8 Zn(2+) and 3.48 ± 0.75 Cu(2+) mg/g for the case of ZnO and CuO NPs respectively (at 1000 mg/L). For mixture of NPs, uptake of 3.18 ± 1.05 mg/g of Cu(2+) and 3.18 ± 1.05 mg/g of Zn(2+) ions were found. The results shows that water containing low concentration of NPs (10 mg/L) can be used for irrigating spinach grown in soil media as no significant toxic effect on growth and uptake of metal ion were found as compared to control. The results of this study evaluated the suitability of reusing water contaminated with NPs in agriculture. Further studies are however required to understand the toxic mode of action of mixture of NPs on growth and uptake mechanisms.