Abstract: The response of seed dormancy and germination to temperature is closely related to species distribution. Understanding the response of weed seed germination to temperature is of great significance for predicting its potential invasion area and preventing and controlling. In this study, we examined the response of seed dormancy and germination of three common tropical Mimosa species (M. pudia, M. diplotricha and M. diplotricha var. inermis) to temperature variation (25, 30, 35 and 40 ℃). The results showed that: (1) Seeds of three Mimosa species had physical dormancy. The seed hardness percentage of M. pudia, M. diplotricha, and M. diplotricha var. inermis were 91%, 96%, and 100%, respectively. (2) High temperature (40 ℃) could effectively promote the release of physical dormancy of M. pudia seeds. According to the observation of seed coat microstructure, under the palisade layer of M. diplotricha and M. diplotricha var. inermis seeds were composed of a layer of osteosclereids with thickened and lignified cell walls and several layers of hardened parenchyma tissue. There were only a few layers of hardened parenchyma tissue under the palisade layer of M. pudia seeds. High temperature increased the permeability of seed coat structure of special parts, such as lens, hilum, and micropyle, thereby effectively breaking the physical dormancy of M. pudia seeds. Our results can provide basic theoretical reference for resisting the further invasion of this species in China and reducing its ecological harm.

Key words: Mimosa, dormancy release, germination, high temperature, invasive weed