Efficacy of a Bacillus velezensis strain in the biocontrol of sugar beet root rot caused by Sclerotium rolfsii

Abstract

In a previous study, Bacillus velezensis NC318, an antagonistic bacterial strain isolated from the rhizosphere of the soil of a date palm crop in the Tafilalet region, showed a high in vitro antagonistic potential against sugar beet root rot caused by Sclerotium rolfsii Sacc. The present work consisted in evaluating in vivo the incidence and severity of the disease on sugar beet plants in pots under a greenhouse. 147 days after sowing in a soil infested with sclerotia of this pathogen (40 sclerotia /250 g of soil), the results showed that the bacterium applied by bacterization of the seeds or in the naturally infested soil was able to totally inhibit the germination of the sclerotia and subsequently no infection of sugar beet plants was observed. Moreover, an improvement of plant growth parameters (fresh weight of the aerial part of the plants, fresh weight of the roots, length of the shoots and, the number of leaves) of plants from seeds treated with strain NC318 was recorded. Viability testing of the antagonist strain NC318 on treated seeds stored at 4 °C, showed that this antagonist remained viable after five months of storage and preserved its antagonistic potential against S. rolfsii tested in vitro. These results suggest that strain NC318 could potentially be a biocontrol agent to control S. rolfsii with a biostimulator effect on plant growth.