EFFECT OF NITROGEN, APPENDAGE REMOVAL, LOCALITY, AND YEAR ON SEED GERMINATION OF THE ENDANGERED DRY GRASSLAND SPECIES PULSATILLA PRATENSIS (L.) MILL.

Pulsatilla pratensis (L.) Mill. is a plant species widely used for ornamental purposes in gardens, but in nature it grows in dry grasslands and is considered an endangered species whose seeds can be directly affected by higher nitrogen (N) deposition. Here we investigate how the germination of Pulsatilla pratensis is affected by concentrations of dissolved nitrogen (NH4+ and NO3- ions), appendage removal, the locality of seed origin, and the year of seed collection. Seeds from different years and two localities, one on clay shale and the other on limestone, were germinated under laboratory conditions in solutions of NH4NO3 ranging from 0 to 4239 mg l(-1) N. Mean germination of seeds from the clay shale locality in 2009 and 2011 and from the limestone locality in 2011 across treatments with low concentrations of N (0-170 mg l(-1) N) ranged between 35 - 49%. Seeds were able to germinate under a wide range of N concentrations, and a substantial decrease in germination rate was recorded only if N concentration exceeded 848 mg l(-1). Seeds germinated in cases where they were totally covered by fungal mycelium, which indicates their high tolerance to fungal infection. There were almost no differences in germination between seeds with and without appendages. Lower germination of seeds collected from the limestone locality could be caused by calcareous bedrock connected with very low P and high Ca availability in the soil, producing lower P and higher Ca concentrations in seeds than at the clay shale locality. Seeds from the clay shale locality also showed differences from year-to-year. We conclude that common N concentrations in rainwater, which range from 10 to 13 mg l(-1) N in Prague, and seed appendage removal have no direct effect, but locality, weather conditions during pollination and seed development play important roles in the establishment of Pulsatilla pratensis seeds.