Acidity and availability of aluminum, iron and manganese as factors affecting germination in European acidic dry and alkaline xerothermic grasslands

Germination ecology of 10 species from acidic dry grasslands and 10 species from alkaline xerothermic grasslands was studied. The seeds were subjected to different pH, iron (Fe), manganese (Mn) and aluminum (Al) treatments under controlled conditions. Effects of ionic (chlorides) and chelated forms (HBED chelates) of Fe and Mn were also compared. Final germination percentage (FGP) and index of germination velocity (IGV) were calculated. The results indicate that pH and extremely high availability of Al are the major edaphic filters regulating germination-based revegetation, while availability of Fe and Mn is of the secondary importance. Both chelates and ionic forms of Fe and Mn exerted similar effects on the ability of seeds to complete germination. It suggests that both chelates are not hazardous for early ontogenetic stages of plants. Neither group has group-specific adaptations pertaining to germination characteristics in the context of the studied chemical stimuli, which indicates a diversity of germination strategies and individual species-specific reactions to the tested factors.