Abstract:

Seed germination characteristics of 7 spatially isolated populations of the endangered plant Euonymus chloranthoides were studied in the laboratory condition.The differences of the seed germination rates among 7 populations were found to be extremely notable.The seed germination rates of the studied populations are positively correlated with their population sizes,while show no correlation with the soil parameters.The differences of the seed germination rates between big populations and small populations reach the extremely notable level.The average seed mass of 7 populations are not copiously correlated both with their population size and with soil parameters in the habitats,which indicates that the average seed weight of a studied population is relatively stable and less influenced.The low seed germination rate in smaller populations may mainly due to the inbreeding depression,and/or loss of genetic diversity in the isolated,smaller populations,while not due to the environmental factors.The study suggests that we should take both the non-genetic,demographic factors and the genetic factors into consideration and enlarge the population to maintain higher seed germination rate and restore the normal regenerations among the smaller and isolated populations of this endangered plant.

Key words: seed germination, isolated populations, endanger plant, Euonymus chloranthoides