Effects of rhizobacteria and seed oils as eco-friendly agents against Meloidogyne incognita infested pepper plants under greenhouse and repeated applications field conditions

Abstract

Proper soil management using rhizobacteria in combination with eco-friendly materials such as plant oils can considerably influence soil ecological processes through soil biota, resulting in changes in the structure and function of soil fauna. This work aimed to investigate the effectiveness of rhizobacteria and oils in vitro besides soil management under greenhouse and field circumstances against root-knot nematode, Meloidogyne incognita. Commercial rhizobacteria and four seed oils plants including, Colocynth, (Citrullus colocynthis (L.), jojoba, (Simmondsia chinensis, Link) Schneid., moringa (Moringa oleifera Lam). and marjoram oil (Origanum majorana L.) were tested in vitro on eggs and J2 of M. incognita using egg immobility and hatchability assay, larvicidal assay, and in vivo under greenhouse and field conditions. Compared to the infected plants, significant effects (p ≤ 0.05) were observed in the tested oils stock solutions and recommended application rate (RC) of rhizobacteria versus eggs and J2 of M. incognita in vitro. Under greenhouse environment, curative application by oils and rhizobacteria significantly promoted fresh shoot, fresh root, weight and leaves count of pepper plants than the control. Rhizobacteria and oxamyl resulted in a significantly elevated plant root and shoot weight percent than other tested materials compared with infected plants. As well as, pots treated with rhizobacteria ranked next to oxamyl in decreasing galls number and egg masses, whereas pots treated with O. majorana showed the lowest nematicidal effect. Field evaluation of eco-friendly materials against M. incognita in naturally infected tomato plants revealed that repeated application by rhizobacteria and oils mixtures exhibited better results in declining galls numbers, egg masses, and J2 density in soil. These findings suggest that a possible mechanism by rhizobacteria and oils can manipulate plant plant-parasitic nematodes behaviour in field soils and potentially reduce nematodes damage.