Interaction of VAMycorrhiza and Root-Knot Nematode on Tobacco Plants: Effects of Nematode Inoculum Density, Soil Texture and Soil Sterilization

The impact of VA-mycorrhizal fungi and root-knot nematodes, on tobacco (Nicotiana tabacum L.) plants, and the possibility of reducing the harmful effects of root-knot nematodes using VAM fungi, was carried out in pot experiments. The VAM fungus, Glomus intraradices significantly increased cured leaf, shoot and root dry weights and phosphorus (P) content of tobacco plants infected or un-infected with nematodes, whereas Meloidogyne incognita significantly reduced them, in sterilized and unsterilized natural soil. Number of galls (nematode infection) on infected roots, significantly increased with an increase in nematode inoculum density and significantly reduced by G. intraradices whereas, mycorrhizal infection percentage was not significantly affected by M. Incognita. Mycorrhizal infection percentage and number of galls were not affected by soil texture, however, better growth of mycorrhizal plants was observed in silt than in clay soils. The results indicated that the use of G. intraradices is a promising technique for agricultural production and could be used as a biofertilizer and biocontrol agent against root-knot nematodes.