Foliar application of silicon nanoparticles affected the growth, vitamin C, flavonoid, and antioxidant enzyme activities of coriander (Coriandrum sativumL.) plants grown in lead (Pb)-spiked soil

Lead (Pb) is among the most abundant toxic trace elements which causes direct and indirect negative effects on humans, animals, and plants. Thus, there is a need to alleviate the Pb toxicity in plants for good quality food production especially from marginal soils. In this study, the effects of silicon nanoparticles (Si NPs) were investigated on coriander (Coriandrum sativumL.) biomass, vitamin C, flavonoid, antioxidant enzyme activities (i.e., catalase (CAT), peroxidase (POD), and super oxide dismutase (SOD)), malondialdehyde (MDA), and Pb concentration in plants subjected to different Pb concentrations. Treatments included four levels of Pb (0, 500, 1000, and 1500 mg/kg of soil), and two levels of Si NPs (0 and 1.5 mM) in all combinations. The Pb treatments alone decreased the plant biomass and vitamin C while increased the flavonoid, MDA, antioxidant enzyme activities, and Pb concentration in tissues depending upon the Pb treatments. The foliar-applied 1.5 mM Si NPs alleviated the adverse impacts of Pb on coriander plants which were due to the minimization of Pb concentration in plants and improvements in the plant defense system. Si NPs minimized accumulation of MDA in plant tissues and adjusted the activities of POD, CAT, and SOD in plants under Pb stress. Overall, Si NP foliar application might be a suitable approach in reducing the Pb concentrations in plants. However, field studies with various plant species and environmental conditions are required to highlight the role of Si NPs on the plant under toxic trace element stress.