Enhancement of cadmium uptake in Cinnamomum camphora seedlings through the regulation of physiological resistance by three exogenous plant growth regulators

Abstract

This study examined the effects of three exogenous plant growth regulators on the resistance physiology of Cinnamomum camphora (C. camphora) seedlings and their cadmium (Cd) absorption and transport under Cd stress. To this end, the efficacies of several plant growth regulators in the remediation of Cd-polluted soil were compared. This paper also provides a theoretical foundation for the ecological restoration of C. camphora and the incorporation of plant growth regulators in mining-abandoned and industrially polluted lands. The findings revealed that the application of 20 mg kg^–1 3-indole acetic acid (IAA), gibberellin (GA₃), and 6-benzylaminopurine (6-BA) facilitated plant growth and enhanced the photosynthesis of C. camphora seedlings. Furthermore, the antioxidant capacity of C. camphora seedlings was improved: the superoxide dismutase activity decreased by 1.0 %, 11.7 %, and 24.4 %. Similarly, the ascorbic acid content decreased by 39.0 %, 17.9 %, and 22.2 %, respectively. These changes effectively boosted the ability of C. camphora seedlings to restore Cd-contaminated soil, consequently promoting Cd accumulation in plant organs and lowering soil Cd residue by 30.8 %, 12.9 %, and 18.1 %, respectively. The treatments also enabled Cd accumulation in the aboveground and underground parts of the seedlings, effectively increasing their resistance against Cd. These results demonstrate that applying plant growth regulators is a promising approach for strengthening phytoremediation in contaminated soils.