Root-centered physiological responses of Panax ginseng to cadmium stress: Growth inhibition, osmotic adjustment, and antioxidant defense

Cadmium (Cd) contamination critically affects the safety and quality of medicinal plants, yet the stage-specific physiological responses of Panax ginseng to Cd stress remain poorly understood. Using two-year-old P. ginseng seedlings, we established four Cd concentration gradients to evaluate growth, osmolyte regulation, and root antioxidant enzyme activities. Results showed that Cd stress significantly inhibited growth: at day 60 under the Cd10 treatment, root length, fresh weight, and dry weight decreased markedly versus control, with dry weight dropping by 51.25%, indicating that root biomass is especially sensitive to prolonged high Cd exposure. Photosynthetic pigment composition and organ-level proline and soluble protein contents varied numerically but not statistically across treatments at either time point. Root antioxidant enzymes responded in a concentration-dependent manner—moderate Cd stimulated several enzyme activities, whereas prolonged high Cd weakened or abolished such induction, implying diminished coordinated enzymatic defense under extreme stress. Overall, Cd stress suppresses P. ginseng via integrated inhibition of growth, disruption of photosynthetic pigments, altered osmolyte partitioning, and modulated antioxidative capacity. This work provides a physiological foundation for understanding Cd‐contaminated soil effects and for exploring mechanisms of Cd‐induced growth restriction and stress adaptation in P. ginseng .