The potential of Bacillus subtilis and Rhizobium leguminosarum in controlling plant-parasitic nematodes in farmers’ fields

Abstract

Assessment of the potential of dual inoculation of Bacillus subtilis and Rhizobium leguminosarum biovar phaseoli strain USDA 2674 on plant parasitic nematodes in bean was carried out on farmers’ fields. Bean seeds variety Rose Coco, were treated with three B. subtilis isolates namely K158, K194 and K263 singly or in combination with Rhizobium and then planted in nematode infested fields. Plant parasitic nematodes in the genera Meloidogyne, Pratylenchus and Scutellonema were dominant. Nematode diversity assessed by Shannon, Simpson’s, Trophic and Maturity indices declined with increased length of cultivation. Plant parasitic index was 63% higher in the cultivated farms compared to the natural forest. The dual innoculant enhanced nodulation variably depending on the length of cultivation and increased bean yields compared to the control. Bacillus subtilis isolates K194, K158 and K263 suppressed plant parasitic nematodes by 42, 36 and 28%, respectively. The potential of dual inoculation of Bacillus and Rhizobium in addressing nematode and soil fertility challenges was demonstrated in this study. Key words: Diversity, Kakemega, Kenya, nodulation, Phaseolus vulgaris