Influence of salinity on the growth and heavy metal accumulation capacity of Spirodela polyrrhiza (Lemnaceae)

Abstract

Given that the characteristic of free floating plants to uptake metals can have a positive effect on the efficiency of the remediation process of a wetland, it is important to investigate the factors that may impact the process of uptake of metals by the plants. By conducting this present study over a short duration of time, the effects of salinity on the growth, the content of the photosynthetic pigments (chlorophyll a, b, and carotenoid), and heavy metal uptake by Spirodela polyrrhiza were investigated. It was also observed that at a high level of salinity (100 and 200 mM NaCl) the relative growth rate (RGR) of the plant decreased. Especially, at a salinity level of 100 mM NaCl, the RGR values were noted to become negative. The content of photosynthetic pigment was negatively correlated with the salt level. Additionally, a high level of salinity was observed to cause a decrease in the accumulation of the metals cadmium (Cd) and nickel (Ni) by S. polyrrhiza.