Use of Sonneratia apetala allelopathy to control Spartina alterniflora weed

Previous studies showed that Sonneratia apetala Buch.Ham could control the spread of exotic invasive plant Spartina alterniflora Loisel. However, little is known about the mechanism for control of S. alterniflora. S. apetala proved to be allelopathic, which played important role in plant interspecific competition. Thus we hypothesize that allelopathy is one of the mechanisms that allowed the S. apetala to displace the S. alterniflora. To test this hypothesis, we studied the allelopathic effects of leaf volatiles and soil of the two plants on three target spp.: Medicago sativa L., Lolium perenne L. and Sorghum Sudanense (Piper) Stapf. The volatiles of both S. apetala and S. alterniflora reduced the germination rate and seedling growth all test spp. The volatiles of S. apetala were more allelopathic than S. alterniflora. Furthermore, the soils from different communities (S. apetala community, S. apetala + S. alterniflora community, S. alterniflora community) were also allelopathic to test plants and S. apetala soil was more inhibitory than S. alterniflora. These results indicated that the S. apetala allelopathy plays an important role in the control of S. alterniflora.