Changes in some physiological traits and mucilage yield of sour tea (Hibiscus Sabdariffa L.) ‎under foliar application of magnesium and iron oxide nanoparticles

In order to investigate the effect of magnesium oxide (MgO) and iron oxide (Fe2O3) ‎nanoparticles (NPs) on physiological traits and the yield of sour tea (Hibiscus Sabdariffa L.), a ‎factorial experiment was conducted in a randomized complete block design (RCBD) with four ‎replications in 2018. MgO and Fe2O3 were used in concentrations of 0.01% and 0.03% as foliar ‎application. The results showed NPS improved chlorophyll (Chl) content and index. The ‎highest total chlorophyll was obtained in plants treated with 0.01% of MgO and 0.0.3% of ‎Fe2O3. Catalase (CAT) and peroxidase (POX) activities significantly increased with NPs, in ‎which all combined concentrations of NPs had greater enzymes activities compared to control. ‎The seed weight in plants treated with 0.03% of MgO and 0.01% of Fe2O3 was higher ‎compared to non-NPs treatment. The highest mucilage yield was found at 0.01% of MgO and ‎‎0.03% of Fe2O3. Total flavonoid content (TFC) in plants treated with 0.01% of MgO and ‎‎0.01% of Fe2O3 was higher than other experimental treatments. The treatment including 0.01% ‎of MgO and non Fe2O3 had lower anthocyanin content compared to other combined levels of ‎NPs. Carotenoid increased with medium concentrations of NPs, but decreased with high level ‎of NPs (0.03%). Protein concentration at 0.01% of MgO and 0.03% of Fe2O3 and 0.03% of ‎MgO and 0.01% of Fe2O3 was higher than other experimental treatments. According tour ‎results, we suggest the use of 0.01% of MgO and 0.03% of Fe2O3 for improving the ‎physiological properties of sour tea. ‎