Research Progress on the Invasion Mechanism of Erigeron annuus

Erigeron annuus(L.)Pers.,an alien species,is widely distributed in most areas of China.It was included in the third batch of invasive alien species list by the Ministry of Ecology and Environment of China,and it is a first-level malignant invasive plant.Due to its great reproducibility with a mass of seeds,power adaptability to the external environment and strong allelopathy,it has highly invasive and adaptability,and has affected the development of the agriculture and forestry,the diversity of local species and the ecosystem.In this paper,we summarized the current invasion situation,invasion and adaptation mechanism of E.annuus,and prospected further research on E.annuus invasion mechanism,hoping to provide a reference for realizing its effective management.

Allelopathic Effects of Extracts from Three Asteraceae Plants on Seed Germination and Seedling Growth of Four Plants

[Objectives]This study was conducted to investigate the allelopathic effects of the extracts of Asteraceae plants on plant seeds and seedlings.[Methods]The effects of the extracts of three Asteraceae plants(Erigeron annuus,Bidens pilosa and Inula japonica)on the seed germination and seedling growth of four plants(Setaria viridis,Erigeron canadensis,Chenopodium album and Lactuca sativa)were studied by the Petri dish filter paper method and bioassay method.[Results]Different concentrations(10,20,40,100,200 mg/ml)of the extracts of E.annuus,B.pilosa and I.japonica had different allelopathic effects on the seed germination of the same recipient plant,and with the increase of the concentrations of the extracts,the inhibitory effects were more significant.The extract of B.pilosa had the strongest inhibitory effect.The extracts at the low concentration(10 mg/ml)had no significant effects on the germination rates and germination energy of the four kinds of plant seeds.In terms of root growth and biomass,the extracts of E.annuus and I.japonica showed the effect of low promotion and high inhibition.Under the treatment with high concentrations(100,200 mg/ml)of the extracts from the three Asteraceae plants,the germination of plant seeds,plant root length,stem height and biomass were inhibited.With the concentrations of the extracts of the three Compositae plants increasing,the chlorophyll contents of the four plants showed a downward trend,and the activity of SOD,POD,CAT and other antioxidant protective enzymes showed a trend of first increasing and then decreasing.[Conclusions]These three species of Asteraceae plants had certain allelopathic inhibitory effects on the germination and growth of the four kinds of plant seeds,including S.viridis,E.canadensis,C.album and L.sativa,and they have potential in the development of botanical herbicides or plant protection.