Growth Response of Vernonia hymenolepis (Sweet Bitter Leaf) Seedlings Inoculated with Arbuscular Mycorrhizal Fungi (AMF) under Fusarium Root Rot Stress in Calabar, Nigeria
J. D. Obeten *
Department of Plant Science and Biotechnology, University of Cross River State, Calabar, Nigeria.
D. E. Akam
Department of Plant Science and Biotechnology, University of Cross River State, Calabar, Nigeria.
N. D. Okena
Department of Biology, University of Education and Entrepreneurship, Akamkpa, Nigeria.
E. E. Akiba
Department of Plant Science and Biotechnology, University of Cross River State, Calabar, Nigeria.
S. E. Udo
Department of Plant Science and Biotechnology, University of Cross River State, Calabar, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: Vernonia hymenolepis is an underutilized African leafy vegetable with important nutritional and economic value, but its productivity is severely threatened by soil-borne pathogens such as Fusarium oxysporum, necessitating sustainable management approaches such as the use of arbuscular mycorrhizal fungi (AMF) to improve growth and disease resistance.
Aims: To determine the influence of two AMF strains on dry biomass of root, stem and leafs of Vernonia hymenolepis under pathogen stress.
Study Design: The experiment followed an 8 × 3 completely randomized design, consisting of eight treatments with three replicates, for a total of 24 pots.
Place and Duration of Study: Calabar in the south- south of Nigeria. A study was conducted between February and May, 2025.
Methodology: Vernonia hymenolepis seedlings were inoculated with two arbuscular mycorrhizal fungi (AMF) strains Glomus mosseae and Glomus gigaspora and subsequently challenged with 50ml of a Fusarium spore suspension under field conditions. Fusarium root rot severity (FRR) and dry biomass were assessed at harvest, 12 weeks after emergence.
Results: The results clearly indicate that all the pathogen stressed seedlings alone (Fo) had higher root percentage disease severity (20.00%) than their combined counterpart with AMF seedlings (Gm+Fo and Gm+Gg+Fo) 1.66% as the lowest. Generally, Vernonia hymenolepis seedlings inoculated with G. mosseae in combination with G. gigaspora and Fusarium (Gm+Gg+Fo) produced the highest significant (P≤ 0.05) root, stem and total dry weight with means values of 10.01, 10.72 and 32.76g/plant-1 . Vernonia hymenolepis plants infected with Fusarium (Fo) alone recorded the lowest severe root, stem, total and root: shoot ratio damage by the pathogen. However, inoculated seedlings with Gg, Gm+Fo and Gm+Gg+Fo gave the highest leaves dry weight and Gm+Gg+Fo recorded the highest root to shoot ratio with value 32.76g/g-1.
Conclusion: Plants inoculated with arbuscular mycorrhizal fungi (AMF) are better able to withstand environmental stresses, including pathogen pressure, and can contribute to the rehabilitation of soils affected by soil-borne diseases in Calabar, Nigeria. Enhanced dry biomass accumulation represents a key mechanism through which mycorrhizal plants express resistance to pathogens.
Keywords: Arbuscular mycorrhizal fungi, Vernonia hymenolepis, Fusarium Root Rot, seedlings inoculated, growth response