Habitat-correlated seed germination behaviour in populations of wood anemone (Anemone nemorosaL.) from northern Italy

Abstract

AbstractAlthough various aspects of the biology ofAnemone nemorosahave been examined, few studies present data on seed germination, and even then information tends to be rather contradictory.A. nemorosaL. is a spring-flowering, woodland geophyte, widely distributed across much of Europe. Germination phenology, including embryo development and radicle and shoot emergence, were investigated in one mountain and three lowland populations from northern Italy. Immediately after harvest, seeds were either sown on agar in the laboratory under simulated seasonal temperatures, or placed in nylon mesh sachets and buried in the wild. Embryos, undifferentiated at the time of dispersal, grew under summer conditions in the laboratory and in the wild. However, seeds did not germinate under continuous summer conditions. Radicle emergence in the field was first recorded at the beginning of autumn, when soil temperatures had dropped toc.15°C in the case of the three lowland populations, and toc.10°C at the mountain site. Shoot emergence was delayed under natural conditions until late autumn/early winter, when soil temperatures had dropped toc.10°C in the lowlands andc.6°C at the mountain site. In the laboratory, a period of cold stratification was required for shoot emergence, and this requirement was more pronounced in the mountain population. Seeds of the mountain population completed embryo development, radicle emergence and shoot emergence at cooler temperatures compared with the lowland populations. These results suggest that germination inA. nemorosais highly adapted and finely tuned to local climate. We conclude that seeds ofA. nemorosadisplay deep, simple epicotyl, morphophysiogical dormancy, and this is the first report of such dormancy for the genusAnemone. However, the continuous development and growth of embryos from the time of natural dispersal, and the lack of evidence of developmental arrest under natural conditions, suggests that radicles are non-dormant.