Allelopathic Impact of Erigeron canadensis and Erigeron annuus on Major Crop Species

This study investigates the allelopathic potential of two invasive plants from the Asteraceae family, Erigeron canadensis L. and Erigeron annuus (L.) Desf., which are prevalent in Heilongjiang Province, China. We systematically examined the effects of water extracts from these plants at various concentrations (25, 50, 75, and 100 g·L−1) on the germination and seedling growth of three major food crops: wheat (Triticum aestivum L.), rice (Oryza sativa L.), and corn (Zea mays L.). Using the Petri dish method and two-way ANOVA with SPSS27 software, we assessed the interaction effects of species and concentration on these crops. The results revealed differential chemosensory effects between E. canadensis and E. annuus extracts. Specifically, the aqueous extract of E. canadensis at 25 g·L−1 promoted wheat root length, while all other growth indicators showed inhibitory effects. The inhibitory effects on wheat, rice, and maize increased with the concentration of the leaching solution. At 100 g·L−1, E. annuus extract completely inhibited the germination of wheat and rice, with an integrated sensitization effect index of −1. The inhibitory effects of the extracts on seed growth indices were in the order of shoot length > root length > biomass. Wheat was the most affected among the three crops, followed by rice, and maize was the least affected. The allelopathic potential of E. annuus was more substantial than that of E. canadensis.