Rhizosphere-driven integrated management of Meloidogyne incognita in tomato (Solanum lycopersicum) using Arthrobotrys oligospora and salicylic acid through enhanced plant defense responses

Root knot nematodes (Meloidogyne spp.) is a major group of plant-parasitic nematode that severely reduce crop productivity by hijacking host root resources. Environmental and toxicological risks associated with chemical nematicides drive the need of eco-friendly management strategies. Therefore, a greenhouse experiment was conducted to assess the single/joint suppressive effects of Arthrobotrys oligospora and salicylic acid (SA) in tomato (Solanum lycopersicum) plants infected with Meloidogyne incognita. Compared to single treatment, combined (A. oligospora + SA) application exhibited pronounced improvement in growth, biochemical parameters, and yield attributes in nematode-infected tomatoes. The combined treatment significantly (P < 0.05) enhanced β-1,3-glucanase, phenylamine ammonia lyase (PAL), peroxidase (POD), and superoxide dismutase (SOD) activities, while significantly (P < 0.05) decreased in proline and malondialdehyde (MDA) content when compared with nematode-infected plants. The combined treatment of A. oligospora and SA significantly decreased nematode infection parameters, disease index, and reproduction factor in nematode-infected tomato. Histological analysis showed that A. oligospora reduced nematode penetration and feeding site development, whereas roots infected solely with M. incognita displayed pronounced vascular bundle damage. These findings demonstrate that the combined application of A. oligospora and SA effectively suppressed M. incognita infection and enhanced tomato defence responses under greenhouse conditions.