Activity and reproductive capability of Meloidogyne incognita and sunflower growth response as influenced by root exudates of some medicinal plants

Abstract

Abstract Two experiments were separately conducted to test the effect of root exudates of seventeen medicinal plant species on hatching and survival of the root-knot nematode, Meloidogyne incognita, in-vitro and in-vivo on infected sunflower cv. Giza 102. In vitro tests, rosemary and marjoram root exudates were the best treatments for inhibiting egg hatch at all concentrations. Nematicidal and nematistatic effects of exudates were concentration-dependent, as the anesthetic effect was obvious especially at low concentrations. In vivo experiment, marjoram and rosemary root exudates significantly reduced the numbers of galls, egg-masses on roots, eggs/root and reproduction factor (Pf/Pi) in all times of application. Furthermore, immersing juveniles in marjoram exudates for 90 min before inoculation caused approximately 50% reduction in Meloidogyne incognita infection and fecundity. Treatments of rosemary at all times of application were the best in improving plant fresh and dry weights. GC/MS/MS analysis revealed that the most abundant components in the root exudates of marjoram and rosemary were flavonoids, phenolics and terpenoids which were suppressive to nematode survival, development and reproduction regardless to their time of application.