Nematicidal properties of leaf extracts of Ruta graveolens inoculated with arbuscuiar mycorrhizai fungi

摘要

The effect of arbuscuiar mycorrhizai fungi (AMF) on the nematicidal activity of rue (Ruta graveolens) against the root-knot nematodes, Meloidogyne incognita and M. javanica, was studied in two in vitro experiments. In the first experiment, egg massesof M. incognita and M. javanica were immersed for 3 weeks in aqueous leaf extracts of rue plants non-inoculated or previously inoculated with Glomus mosseae or mixed AMF strains (Sclerocystis sinuosa, Glomus claroideum-l, G. claroideum-2 and G. claroideum-3). Thereafter, the hatching test continued in distilled water for a further 5 weeks. In the second experiment, egg masses of both Meloidogyne species were exposed to the different rue extracts for 4, 8 and 16 h and then incubated in distilled water for 8 weeks. Distilled water and 5 mu g ml~(-1) aqueous solution of the nematicide fenamiphos were used as controls. In the first experiment the emergence of juveniles from eggs of both Meloidogyne species was suppressed by R. graveolens extracts after thefirst eek, with no significant differences among the treatments. Hatching in extracts of R. graveolens was significantly lower than that in water control or fenamiphos solution. Frequencies of AMF infection on the root of rue were 93 and 97% for G. mosseae and mixed AMF, respectively. In the second experiment a 4 h immersion of M. incognita egg masses in the extract from R. graveolens + mixed AMF reduced egg hatch compared with distilled water. Other extracts significantly suppressed final hatch of both Meloidogyne species only after 16 h of exposure. Both AMF populations significantly increased the growth of R. graveolens but the nematicidal activity of rue leaf extracts was not affected by inoculation of plants with AMF.