Inoculation of Fava Bean Plants (Vicia faba L.) with a PGPR Combination Suppresses the Impact of Root-Knot Nematode and Promotes Plant Growth

Plant-growth-promoting rhizobacteria (PGPR) are a class of beneficial bacteria that colonise the roots of plants and improve projected plant growth through a multivariate process. PGPR application is increasing steadily in the field of agriculture, providing an attractive mechanism to replace pesticides, chemical fertilisers and additional supplements.

In this study, PGPR from rhizospheric soil collected from Abha, a city located in the southern region of the Kingdom of Saudi Arabia (KSA), were isolated and characterised to facilitate verifying the efficacy of using PGPR as a biological control to improve fava bean growth. Four bacterial isolates from the nodules of fava bean plants, S4, S5, S6 and S17, were isolated and characterised. Consequently, an investigation highlighting the impact of PGPR isolates on the preservation of fava bean plants from the root-knot nematode was conducted through a pot culture experiment. Soil infested with the nematode was added to the pots. Two commercial types of fava bean plants (Vicia faba L.) were co-inoculated with PGPR 15 days after planting.

The results reveal that the nodule-forming bacteria interact synergistically; this was evidenced by a prominent increase in the shoot length and dry weight of the fava bean plants that had been cultivated in the nematode-infested soil. The results also demonstrate that the overall treatment of the plants did not lead to nodule formation. The results indicate that nodule-forming bacteria could be utilised in leguminous crops to facilitate biocontrol of the root-knot nematode.