Tolerance, enrichment, and transportation of Viola prionantha under lead stress

To screen plants suitable for heavy metal contaminated areas, plant growth, physiological characteristics, and Pb absorption and transportation characteristics were observed. V. prionantha seedlings were chosen as experimental material for hydroponic experiments, setting six concentrations (0, 10, 25, 50, 100, 200 mg·L⁻¹) to determine tolerance, enrichment, and uptake characteristics under lead stress in five testing periods (non-stress, 5 d, 10 d, 15 d, 20 d). Under the same treatment and different testing period, high concentrations significantly inhibited the growth of V. prionantha (P < 0.05); with the increase of stress concentration, the antioxidant enzyme system and malondialdehyde (MDA), proline, and soluble sugar contents gradually increased, but soluble protein content decreased. Chlorophyll content, net photosynthetic rate (P_n), stomatal conductance (G_s), and transpiration rate (T_r) showed a decreasing trend, whereas intercellular carbon dioxide concentration (C_i) increased continually. The Pb²⁺ content in the underground part was higher than that in the aboveground part in this experiment but V. prionantha had lead enrichment ability, while transportation ability was weak. Therefore, V. prionantha has a certain resistance to lead concentration and has application potential.