The Combined Effects of Soil Sterilisation and Organic Mulching on Fusarium Crown Rot Incidence and Growth Performance in Amaranthus viridis L

Abstract

Amaranthus viridis L. is a nutrient-rich leafy vegetable with considerable potential to alleviate food insecurity in tropical regions. Despite its nutritional value and high yield potential, its production remains suboptimal, even under favourable growing conditions, largely due to Fusarium crown rot caused by Fusarium oxysporum. This study examined the synergistic effects of soil sterilisation and organic mulching on the suppression of Fusarium crown rot and the enhancement of growth in A. viridis. The experiment was conducted in a screenhouse facility at the Department of Biological Sciences, Tai Solarin University of Education, Ijagun, Ogun State, Nigeria. Seeds were sourced from Oke-Aje Market, Ijebu-Ode. A completely randomised design with six replicates was employed. A 2 × 2 factorial arrangement was used to evaluate soil sterilisation (autoclaved versus unsterilised) and organic mulching (5 cm layer of dried Tectona grandis leaves versus no mulch). The results revealed significant differences (p < 0.05) in plant height and leaf number across treatments. The sterilised and mulched treatment recorded a 42% increase in plant height and a 38% increase in leaf number compared with the control. Disease incidence was lowest in the sterilised and mulched soil (12.0 ± 2.1%) and highest in the unsterilised, unmulched control (54.3 ± 5.6%). Organic mulching effectively moderated soil temperature (±1.5°C diurnal variation), thereby creating conditions less favourable for the development of F. oxysporum. These findings demonstrate that soil sterilisation significantly improves the growth performance of A. viridis while reducing pathogen incidence. When combined with organic mulching, which regulates the soil microclimate, this approach offers effective protection against Fusarium crown rot. The combined application of soil sterilisation and organic mulching is therefore recommended as a sustainable strategy for enhancing A. viridis production.