Abstract: Toxicity test and pot experiment were conducted to study the nematocidal activity and control effects of Ricinus communis extracts on Meloidogyne incognita. The results showed that both the ricinine and the R. communis water extracts had high nematocidal activity. The ricinine at concentration 2 g·L^-1 and treated for 48 hours had the strongest nematocidal activity, leading to 91.5% of corrected mortality of M. incognita and with the LC₅₀ being 0.6 g·L^-1, whereas the R. communis water extracts at concentration 100 g·L^-1 and treated for 48 hours had the strongest nematocidal activity, which led to 83.5% of corrected mortality of M. incognita, and the LC₅₀ was 18.3 g·L^-1. With the inoculation of M. incognita treated with ricinine, R. communis water extracts, and R. communis leaf powder, respectively, on tomato seedlings, the mean number of plant root-knots was 17.6±1.7, 20.6±1.5 and 22.8±3.7, respectively, being significantly lower than the control (37.4±2.3), and the root length  increased by 46.8%, 34.5% and 33.8%, and the plant height  increased by 33.5%, 22.6% and 15.8%, and the fresh mass  increased by 41.4%, 18.9% and 10.1%, respectively,  compared with the control. All the results suggested that R. communis extracts could mitigate the harm of M. incognita, and had obvious effects on potted tomato against M. incognita.

Key words: Ricinus communis, extract, Meloidogyne incognita, nematocidal activity