Interaction between mycorrhizal fungi and Meloidogyne javanica on the growth and essential oil composition of basil (Ocimum basilicum)

Plant-parasitic nematodes and arbuscular mycorrhizal fungi (AMF) have been reported to alter the yield and chemical composition of basil (Ocimum basilicum) essential oil. The aim of this study was to evaluate the effectiveness of AMF to control the root-knot nematode Meloidogyne javanica in basil and to investigate the effects of nematode-AMF interactions on plant growth, phosphorus (P) absorption, and essential oil composition. The experiment was conducted under greenhouse conditions following a completely randomized 3 × 2 factorial (two fungal species and an uninoculated control × inoculated and uninoculated seedlings) arrangement with 10 replicates. Substrates were inoculated with Claroideoglomus etunicatum, Rhizophagus clarus, or no fungi (control) and sown with basil seeds. After 20 days, half of the seedlings were inoculated with 4,000 M. javanica eggs. After 60 days, the vegetative parameters, P absorption, essential oil composition, nematode population density, AMF root-colonization efficiency, and AMF spore density were determined. The presence of AMF increased the basil’s fresh weight and ability to absorb P, while reducing the M. javanica reproduction. In total, 21 compounds were identified in basil essential oil, the concentrations of which varied according to the treatments. The major components were eucalyptol, linalool, eugenol, β-elemene, trans-α-bergamotene, and τ-cadinol. Inoculation with AMF decreased the linalool levels but increased the amount of eucalyptol. Mycorrhizal plants showed increased shoot height, P uptake, and essential oil yield and a decreased nematode population density in their roots.