Effect of Pb pollution on the growth,biomass allocation and photosynthesis of Phragmites australis in flood and drought environment北大核心CSCD

Aims Reed (Phragmites australis) is a typical perennial rhizomatic plant with extensive tolerance to environmental stress. In order to better understand the adaptation and tolerance of reeds subjected to heavy metal pollution in different levels of water, we conducted a study on the effects of Pb pollution on growth, biomass and photosynthesis of reeds in flood and drought environment. This research would provide theoretical basis for application of reeds in wetland restoration and remediation. Methods We conducted a pot experiment with destructive sampling after 90 days of growth. The water treatments were main plot, including two water levels. The Pb treatments were secondary plot (nested within water treatments), including five levels (0, 500, 1 500, 3 000, 4 500 mg·kg–1). There were 10 treatments with 12 replicates per treatment. Important findings In the flood environment, Pb pollution significantly inhibited the growth of buds and rhizomes, but had no significant effect on the number of offspring shoots. The offspring shoots had higher growth rate per day, net photosynthetic rate and biomass compared to the parent shoots. In the drought environment, Pb pollution inhibited the growth of roots, buds and rhizomes, and biomass accumulation of parent and offspring shoots as well as photosynthetic parameters. These parameters were lower under the drought condition than in the flood environment. The Pb was mostly concentrated in roots compared to rhizomes and offspring shoots. In both flood and drought environments, the concentration of Pb in parent shoots was about three times of that in offspring shoots. The Pb concentration in offspring shoots under the flood condition was less than that in the drought environment. Overall, these results indicated that the synergistic effect of Pb and drought significantly inhibited the growth, biomass accumulation and photosynthesis of reeds, which might result in reduced offspring productivity and population density and may lead to population decline. However, the flooded reeds could adopt some strategies of Pb allocation to alleviate the negative effect of Pb on the growth, physiology and clonal propagation, benefiting the population reproduction and stabilization. © 2018 Editorial Office of Chinese Journal of Plant Ecology. All rights reserved.