Dose-dependent suppression of Meloidogyne incognita and enhancement of antioxidant defense in banana plants by Millettia pachyloba Drake leaf extract

This greenhouse study evaluated the dual nematicidal and antioxidant potential of the aqueous leaf extract of Millettia pachyloba Drake in banana (Musa spp.) infested by Meloidogyne incognita. Banana plants were treated with increasing extract concentrations (200–500 ppm) and compared with a nematicide (oxamyl, 30 ppm) and a water control. Nematode control efficiency (NCE), plant growth, oxidative stress biomarkers and antioxidant indicators were assessed. The extract suppressed M. incognita in a clear concentration-dependent manner, with NCE reaching 40.19 ± 0.46 % at 500 ppm (p = 0.0176) and strong negative correlations between dose and nematode infection parameters (generally r ≤ -0.97). Pseudostem height showed the strongest growth response, increasing by approximately 36.4 % between 200 and 500 ppm (p < 0.05), whereas diameter and biomass improved more moderately. Extract application reduced malondialdehyde (MDA) and reactive oxygen species (ROS) in roots (e.g., MDA: r = -0.9909, p = 0.0137), while enhancing enzymatic (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx)) and non-enzymatic (GSH, GSH/GSSG) antioxidant systems. These integrated responses suggest that aqueous M. pachyloba leaf extract may serve as a promising dual-function, plant-derived input that could contribute to M. incognita suppression and mitigation of nematode-induced oxidative damage in banana, although field validation is still required.