GERMINATION RESPONSES OF 64 WETLAND SPECIES IN RELATION TO SEED SIZE, MINIMUM TIME TO REPRODUCTION AND SEEDLING RELATIVE GROWTH-RATE

Three germination attributes (lag time, maximum germination rate, and final germination proportion) were measured for 64 species of herbaceous wetland plants. The environmental conditions approximated the drawdown environment known to stimulate germination in wetland plants: a period of cold stratification followed by position of the seed on the surface of wet, but not inundated, substrate in the presence of light and with a 20/30-degrees-C daily temperature cycle. Correlations were sought between the three germination attributes and average individual seed weight, seedling relative growth rate and a categorical variable indicating miminum time to reproduction (annuals, facultative annuals and obligate perennials). Average seed weight was not correlated with any of the three germination attributes. Seedling relative growth rate was negatively correlated with time to initiation of germination. Species capable of setting seed their first year (annuals and facultative annuals) initiated germination sooner, a larger proportion germinated per day once germination began, and a larger proportion of seeds had germinated by the end of the experiment in comparison with species which require more than 1 year to set seed (obligate perennials). A discriminant analysis showed that the time to initiation of germination could accurately classify 89% of the perennial species as being either facultative annuals or obligate perennials.