Does gypsum infuence seed germination?

Abstract

Flora inhabiting gypsum outcrops in arid environments shows a high level of specialization. However, the processesinvolved are still unclear, specifcally at the key stage of germination. Here, to assess whether gypsum could chemically infuence seedgermination, we tested the germination of species according to 3 functional groups: gypsophiles, gypsovags, and calcicoles. A total of24 taxa were selected, all occurring in gypsum and limestone substrates, under a semiarid and dry Mediterranean climate. Tree levelsof gypsum (CaSO 4·2H 2O) solution (low = 0.5 g/L, medium = 1 g/L, and high = 2.4 g/L) and 1 control treatment of distilled water weretested. Results depended on the particular species rather than on the functional group. We found that gypsum favored germinationin some species ( Lepidium subulatum L. and Gypsophila struthium L.), whereas signifcant negative efects appeared for only 1 species(Rosmarinus ofcinalis L.). In contrast, most of the species studied responded neutrally to gypsum solutions. Our results suggest thatchemical features of gypsum could ofer an advantage at the germination stage for certain species, rather than posing a constraint forseed germination.