Impacts on seed germination features of Eupatorium adenophorum from variable light stimulation and traditional dormancy-broken methods

Eupatorium adenophorum (Crofton weed) is a notorious invasive species worldwide, as the first step colonizing in a new habitat, seed germination and growth of seedlings should be related to its strong invasiveness. Combining experiments on different light intensity and different traditional dormancy-breaking treatments were carried out in this paper. We are aiming to answer two questions, i. e., whether or not germination of the weed is light-required, and how traditional dormancy-breaking methods and light intensity interactively affect germination and seedling growth. Crofton weed had the feature of photoblastic seed germination. Germination under different treatments was higher than 63% under full light, and higher 60% under aluminum foil-covered treatments (0.23% light transmittance), while germination was lower than 30% under dark treatments. Different from previous reports on other species, the low temperature, SA, PEG and KN0 sub(3) treatments cannot take the place of light in breaking seed germination, indicating that Crofton weed was in the form of forced dormancy (seed quiescence). Light with SA and PEG treatments had interactions on seedling growth: SA treatments were linearly related with seedling biomass at dark (P0.05). Similarly, significantly linear correlation between PEG concentration and root length under full-light treatments was found (P > 0.05). This photoblastic seed germination and seedling growth characteristics play a key role in forming soil seed bank, and also the basis of fast-invasion of this species in disturbed soil, where seeds in deep soil come to surface after disturbance. Our finding also supports the ecological control of this invasive species by introducing suitable trees to influence light environment around Crofton weed.