Abstract: Spartina alterniflora is distributed over 20 degrees (20°N to 39°N) of latitude after 40 years of deliberate planting and natural dispersal, which poses a serious threat to coastal and wetland ecosystems in China. Seed germination, a critical stage determining the invasion of S. alterniflora into different latitudes, is affected by temperature. Seed germination characteristics of S. alterniflora would be different at the high latitude and low latitude regions. We explored the response of seed germination of S. alterniflorapopulations from high and low latitude to temperature, with seeds from highlatitude provenance at Dongying (38.0°N) and low-latitude provenance at Leizhou (20.9°N). We measured the germination percentage, germination index, and mean germination time of S. alterniflora seeds under different temperatures (5, 15, 25 ℃). The results showed that: (1) Provenances significantly affected germination percentage and germination time (P<0.0001). Seeds from highlatitudinal provenance had higher germination percentage and longer mean germination time than of those from low-latitudinal provenance. (2) Within 5-25 ℃, rising temperature significantly promoted germination percentage and germination index (P<0.0001), shortened the mean germination time, and advanced the germination peak. (3) Temperature and provenance significantly interacted to affect germination percentage (P<0.001). The effect of temperature on germination characteristics might be due to the enhanced enzyme activity at higher temperature, which accelerated the germination process and altered germination characteristics. The difference of seed germination characteristics between highand low-latitudinal provenances indicated that S. alterniflora adapted to local climate of different geographical areas. Our results suggest that the risk of invasion and diffusion of S. alternifloraat high latitude is higher than that at low latitude.

Key words: Spartina alterniflora, seed germination, temperature.