The role of Fe-nano particles in scarlet sage responses to heavy metals stress.

Despite the stabilized ornamental markets for scarlet sage (Salvia splendens), little is known about the stress resistance of heavy metals (HMs). Therefore, a hydroponic study was conducted to determine whether the addition of Fe nanoparticles (Fe NPs) at 0, 5, 10, 20 and 30 µM in Hoagland's nutrient solution reduce the toxicity caused by 100 μM of HMs (Cd, Cu, Ni, Cr and Pb). Exposure to HMs significantly reduced relative growth rate (RGR), chlorophyll content, chlorophyll fluorescence (Fv/Fm), total antioxidant activity (TAA), total phenol content (TPC) and antioxidant power assay (FRAP), while the malondialdehyde (MDA) accumulation, H2O2 generation and electrolyte leakage (EL) significantly increased. Fe NPs improved HMs toxicity by significant reduction in MDA content, H2O2 generation and EL while increase in the PGR, chlorophyll content, Fv/Fm, the TAA, TPC and FRAP. Exposure to HMs caused Fe deficiency-induced chlorosis while Fe NPs reduced the negative effects of HM by preventing further reduction of leaf Fe. The results highlighted that although using Fe NPs significantly improved plant growth and motivated the plant defense mechanisms in response to HMs toxicity, it had a negative effect on the phytoremediation properties of salvia splendens by reducing the accumulation of HMs in plant organs.