The seed germination properties of two hyperaccumulator plant species with the potential for Ni agromining

The aim of this study is to investigate the effect of different nickel concentrations and light in combination with storage conditions and storage time on the seed germination ability of two serpentine-endemic nickel hyperaccumulating species (Bornmuellera emarginata and B. tymphaea). The seeds of both species were collected from natural populations in the Pindus Mountain range, Greece in early July and stored in a refrigerator (4degree celsius) and in laboratory conditions (22degree celsius). The seeds were exposed to a range of nickel concentrations typical of non-ultramafic - ultramafic gradient in two light environments (12 h photoperiod and continuous darkness). The nickel concentration only had a significant effect on B. emarginata, decreasing its seed germination rate with increasing Ni concentrations. The storage temperature significantly affected the germination percentage of both species and it was higher at 4degree celsius compared to 22degree celsius. A higher germination rate (> 60%) was observed for 5-8-month-old seeds, but conducted seven months after seed ripening in the field. A higher germination rate was observed in a 12-hour photoperiod than in continuous darkness only for B. tymphaea. This study provides guidelines on the germination capacity of systems.