Effect of Bacillus subtilis BD233 on seedlings growth of sweet pepper (Capsicum annuum), Swiss chard (Beta vulgaris) and lettuce (Lactuca sativa)

Abstract

Bacillus species are ubiquitous microorganisms that enhance growth in several crops as well as provide protection against pathogens. In this study, the effects of soil inoculation with B. subtilis BD233 on growth and development of sweet pepper (Capsicum annuum L.), Swiss chard (Beta vulgaris L.) and lettuce (Lactuca sativa L.), were investigated. Three treatments were employed: i) incubation with a lysogeny broth culture of B. subtilis BD233; ii) broth without B. subtilis BD233 (without BD233/control) and iii) tap water. Potting soil-grown seedlings of the three crops were assayed to measure growth parameters over a period of five weeks (35 days) after exposure to the treatments. Soil inoculation with B. subtilis BD233 significantly improved the growth and development of sweet pepper and lettuce seedlings relative to the other treatments but not for Swiss chard. Bacillus subtilis BD233 in lysogeny broth increased the plant height, stem elongation rate and stem diameter of sweet pepper and lettuce seedlings relative to those treated with water. Furthermore, the biomass of sweet pepper and lettuce seedlings exposed to B. subtilis BD233 was increased by 32.2 and 92.6%, relative to their respective controls. However, no statistical differences for height and biomass were found for Swiss chard in response to the treatments. The results of the study demonstrated the potential of B. subtilis BD233 to enhance the early growth of these non-indigenous vegetables in nutrient-poor African soils.