Biocontrol agents in co-inoculation manages root knot nematode [Meloidogyne incognita (Kofoid & White) Chitwood] and enhances essential oil content in Ocimum basilicum L.

Abstract

The biocontrol agents are bestowed with potential to enhance secondary metabolites including essential oil contents. Rhizosphere microorganisms in co-inoculation with arbuscular mycorrhizal fungi (AMF) are better in terms of plant growth-promotion (PGP) and warrants for potential management of soil-borne diseases. The present study was designed to evaluate the impact of microbial bioinoculants in management of root knot nematode, their growth promotion activity and on essential oil contents (quantity and quality) in basil (Ocimum basilicum). The estimated impacts of microbial inoculants on plant growth indices such as shoot fresh and dry weight, root fresh and dry weight, shoot height, mineral content and essential oils indicated that the two Bacillus species (Bacillus tequilensis and Bacillus flexus) alone and in combination with renowned biocontrol agents (Trichoderma harzanium and Glomus aggregatum) performed better in disease management and showed prominent effect on improved essential oil (quantity and quality). Data obtained from in-house and field study explained, significant differences between applied bioinoculants (field – herb yield 16.7–60.7% increment, oil yield – 27.2–51.2%, seed yield – 18.2–51.3%), vs. chemical control (carbofuran – 14%, 20%, 3.7%) and untreated control. The results thus validate that consortia inoculation (bacteria/fungi and AMF) is a better option for eco-friendly and safer management of root knot diseases along with improved growth parameters/yield attributes particularly in concern with economically important secondary metabolites/essential oil contents.