Physiological responses of wetland species Rumex hydrolapathum to increased concentration of biogenous heavy metals Zn and Mn in substrate

The aim of the present study was to determine if individuals of Rumex hydrolapathum Huds native to saline wetlands are able to tolerate high concentration of biogenous heavy metals Zn and Mn in substrate and to accumulate high concentration of these metals in aboveground parts. Plant physiological status was monitored by using non-destructive analysis of chlorophyll and chlorophyll a fluorescence. R. hydrolapathum plants accumulated up to 1840 mg·kg^–1 Zn and 6400 mg·kg^–1 Mn in older leaves. The usefulness of monitoring changes in chlorophyll concentration and chlorophyll a fluorescence parameters to predict physiological response of R. hydrolapathum plants to excess Zn and Mn was not supported, as the lack of significant changes indicated that the model species showed adaptation to increased amount of metals in actively photosynthesizing tissues. It appears that Zn and Mn tolerance of R. hydrolapathum is based primarily at the physiological level where metal accumulation in younger leaves and roots is restricted, and development of new leaves is promoted together with induction of senescence in older leaves that have accumulated the majority of Zn and Mn. R. hydrolapathum can be characterised as a very promising model species for further studies for practical phytoremediation needs.