The tolerance of growth and clonal propagation of Phragmites australis (common reeds) subjected to lead contamination under elevated CO2 conditions

Abstract

Phragmites australis is a rhizomatous perennial plant with extensive distribution and tolerance. To explore plant growth and clonal propagative tolerance to lead contamination under elevated CO₂, they were exposed to combinations of five Pb levels (0, 300, 500, 1500, 3000 mg kg⁻¹) and two CO₂ concentrations (380 ± 20 and 760 ± 20 μmol mol⁻¹) in phytotron. Biomass, photosynthetic parameters and rhizome growth were significantly inhibited, while number of axillary shoot buds and daughter apical rhizome shoots were increased by Pb additions. ∼80% of daughter shoots was from daughter axillary shoots, representing a phalanx growth pattern. Under elevated CO₂, photosynthetic parameters (excluding stomatal conductance and transpiration rate), growth of clonal modules were increased, facilitating plant biomass accumulation, phalanx growth and spreading strategy. The results suggest that elevated CO₂ might improve growth and clonal propagative resistance to Pb contamination through increasing photosynthetic, phalanx growth and population expansion of Phrgagmites australis.