Cadmium and lead mixtures are less toxic to the Chinese medicinal plant Ligusticum chuanxiong Hort. Than either metal alone.

Agricultural production of Ligusticum chuanxiong Hort. is often affected by heavy metal pollution in soil, especially mixtures of cadmium (Cd) and lead (Pb). We assessed metal-induced phytotoxicity in L. chuanxiong by exposing the plants to soil treated with Cd, Pb, or Cd/Pb mixtures. A combined Cd/Pb treatment alleviated the inhibition in plant growth, photosynthesis, and secondary metabolite generation seen in single-metal exposures in three of the four combinations. Most combined Cd/Pb treatments resulted in preferential uptake of magnesium, copper, and nitrogen in underground plant parts and accumulation of phosphorus and calcium in aboveground plant parts, thereby leading to improvements in photosynthetic potential. Compared with single-metal exposures, combined Cd/Pb treatment significantly decreased the contents of Cd by 16.67%-40.12% and Pb by 10.68%-21.70% in the plant, respectively. At the subcellular level, the Pb presence increased the Cd percentage associated with cell wall from 64.79% to 67.93% in rhizomes and from 32.76% to 45.32% in leaves, while Cd reduced Pb contents by 9.36%-46.39% in the subcellular fractions. A combined Cd/Pb treatment decreased the contents of water- and ethanol-extractable metal forms and increased the contents of acetic acid- and hydrochloric acid-extractable forms. The lower toxic effects of the Cd/Pb mixture in L. chuanxiong were associated with photosynthetic potential, subcellular distribution, the chemical forms of Cd and Pb, and synthesis of secondary metabolites. These findings are useful for plant production strategies in soils contaminated by heavy metals.

[Effects of S-3307 on photosynthesis of Ligusticum chuanxiong].

OBJECTIVE: To study the effects of S-3307 spraying time and density on photosynthetic characteristic of Ligusticum chuanxiong. METHOD: The photosynthetic characteristic of L. chuanxiong under different S-3307 spraying time and density was studied by plot cultivation experiment. RESULT: The content of chlorophyll a and chlorophyll b in leaf increased when the spraying density was 20, 40, 80 mg x L(-1), while the net photosynthetic rate was the maximum. When the spraying density was 160 mg x L(-1), the content of chlorophyll a and chlorophyll as well as net photosynthetic rate were not increased. CONCLUSION: S-3307 spraying can raise the photosynthetic capacity of L. chuanxiong and promote the form of assimilation products.