Effects of ZnO NPs on phenolic compounds of rapeseed seeds under salinity stress

In this study, rapeseed Okapi cultivar was treated under three NaCl levels (0, 50 and 100 mM) and four Zinc oxide nanoparticles (ZnO NPs) concentrations (0, 20, 40 and 80 mgL-1) at flowering stage. The experiment was performed in a completely randomized design (CRD) in the greenhouse of Biology Department of Urmia University, in 2015. Results showed that NaCl (100 mM) significantly enhanced total phenolic, flavonoids, anthocyanin and phosphorus contents and increased ability to scavenge the DPPH radical scavenging activity. Treatment with ZnO NPs (80 mgL-1) significantly elevated total phenolic and decreased anthocyanin, phosphorus and zinc contents and seed weight. Foliar application of ZnO NPs ameliorated the negative impacts of NaCl by reduction in phenolic, anthocyanin and phosphorus contents and elevation in seed oil content (20.82%) and seed weight (79.28%) at 50 mM salinity and 20 mgL-1 of ZnO NPs compared to NaCl (50 mM) alone. In conclusion, foliar application of ZnO NPs at 20 mgL-1 is recommended to farmers as replacement for fertilizers to alleviate the adverse effects of salinity stress.