Hana Skálová1, Lenka Moravcová1, Jan Čuda1 and Petr Pyšek1,2
1Institute of Botany, The Czech Academy of Sciences, Zámek 1, CZ-252 43 Průhonice, Czech Republic
2Department of Ecology, Faculty of Science, Charles University, Viničná 7, CZ-128 44 Prague, Czech Republic
Population dynamics of annual species, especially those with less abundant seed banks, depends on the recruitment from seed, a process in which a proper timing of germination is crucial. Previously, we studied the effect of growing conditions in the field on the germination of native and invasive Impatiens species (Balsaminaceae) in the Czech Republic. In the native Impatiens noli-tangere we found a strong effect of spring temperature at the original localities on the germination timing, with seeds from climatically colder localities germinating earlier. A similar but much weaker effect was found in the invasive I. parviflora, and the absence of any such effect was observed in I. glandulifera, a species whose invasion started later than that of I. parviflora (Skálová et al. 2011). In this study, we addressed the effects of cultivation temperature (garden vs greenhouse with increased temperature) and time of seed collection on the germination dynamics of these species. In I. noli-tangere the germination of seeds harvested later in the season was strongly delayed and a high proportion of seed were dormant. The effect of locality was detectable in all seeds, but the size decreased in seeds collected later in the season. Impatiens parviflora seeds from the greenhouse germinated earlier than from the garden and the effect was especially pronounced in seed collected later in the season. In addition, germination was not synchronised in the seeds collected from the garden later in the season. The effect of spring temperature in the original localities gradually diminished with time of collection. Delayed germination in seeds collected later in the season was observed also in the highly invasive I. glandulifera. Surprisingly, the effect of spring temperature in the original localities (i.e. early germination of seeds from colder localities) was observed and it was stronger for seeds collected later in the season. These results indicate strong population differentiation within the native species and ongoing differentiation in the invasives.
Skálová H., Moravcová L. & Pyšek P. (2011) Germination dynamics and seedling frost resistance of invasive and native Impatiens species reflect local climatic conditions. Persp. Plant Ecol. Evol. Syst. 13: 173–180.