Elicitation effect of hydrogen peroxide to enhance tolerance of Taxodium distichum (L.) Rich. seedlings irrigated with saline water

Because of the scarcity of fresh water and its limited availability for human use, some places have resorted to utilizing alternative water sources, such as saline water, which negatively impacts plant growth and development. Hydrogen peroxide (H2O2) signalling molecule, aids in plant defence as a signal in the production of systemic acquired resistance and modulating ROS detoxification and regulating multiple stress-responsive pathways and gene expression. Our study suggests that using H2O2 as a stimulating substance to boost the production of antioxidant compounds in plants resulting in enhanced growth. During the 2022 and 2023 seasons, we used H2O2 as a foliar application at concentrations (0, 20, 40, 60, and 80 mM) on Taxodium distichum seedlings receiving saline water at concentrations (0, 3000, 5000, and 7000 ppm). The results indicated that applying H2O2 at 20 mM enhanced most of growth attributes and lowered the production of proline, lipid peroxidation (MDA), and improved the accumulation of chlorophyll a and b which suggests that plants Irrigated with this concentration were able to handle all of the salt levels. Compared to other treatments, applying a H2O2 at 40 mM treatment resulted in the highest plant Salt Resistance Index (SRI%) and root growth parameters. Carotenoids, flavonoids, phenols, and sugars in the plant reached peak production when treated with a 60 mM of H2O2, regardless of salinity concentrations. The activity of peroxidase (POD) as an antioxidant isoenzyme increased as the salinity and H2O2 concentrations increased. The treatment with salinity at 7000 ppm+ H2O2 at 60 or 80 mM showed the maximum number of bands and the greatest intensity of POD.