Potential allelopathic effects of oat root extract on five plants

To clarify the allelopathy of oat root systems, the effects of different concentrations of oat root extracts on seed germination and seedling growth of five main weeds in the northwest oat field were analyzed in this study via biological activity assay. The results showed that the oat root extract had significant allelopathic effects on the seed germination and seedling growth of the five studied plants (P < 0.05), and there were certain differences in these effects. The root extract promoted seed germination of Brassica napus (RI > 0). However, it inhibited seed germination of Amaranthus spinosus, Chenopodium glaucum, and Setaria viridis (RI < 0). Root extract increased the shoot lengths and fresh weights of A. spinosus, Amaranthus retroflexus, and S. viridis (RI > 0). However, it inhibited the root lengths of A. retroflexus and S. viridis and the fresh weights of B. napus and C. glaucum. The synthetical allelopathic effects of each concentration treatment, on A. spinosus, B. napus, and A. retroflexus were positive (SE > 0), and the order of intensity of these effects, from large to small, was A. retroflexus > A. spinosus > B. napus. The extracts had inhibitory effects on C. glaucum and S. viridis (SE < 0); the inhibition of C. glaucum was stronger than that of S. viridis.