Evaluation of antagonistic Pseudomonas and Bacillus spp. against Meloidogyne incognita causing root-knot disease in okra

Abstract

Efficacy of antagonistic bacteria Pseudomonas and Bacillus against the root-knot nematode (Meloidogyne incognita) in okra as a sustainable biological control strategy was evaluated. All the bacterial treatments significantly reduced nematode populations and root galling while enhancing plant growth and yield compared to the control. Nematode-related parameters showed strong positive correlations among themselves: egg mass per plant (r = 0.998), nematode population  (r = 0.968), and root knot index (r = 0.907), while plant growth parameters showed significant negative correlations with nematode infestation: plant height (r = ?0.983), fresh shoot weight (r = ?0.988), dry shoot weight (r = ?0.990), root length (r = ?0.960), fresh root weight (r = ?0.996), and dry root weight (r = ?0.983). Seed treatment with P. fluorescens at 10g kg^-1 was the most effective, giving the lowest root-knot index (3.33) and the greatest reduction in galls, egg masses, and larvae per 200 cc soil. Although carbofuran showed comparable efficacy, its environmental and health hazards limit its use; thus, seed treatment with P. fluorescens at 10g kg^-1 is recommended as an effective, eco-friendly alternative for managing M. incognita in okra.