Field-scale Variation in Infective Potential and Root Colonization of Indigenous Arbuscular Mycorrhizal Fungi Associated with Plantain in Central-West Côte d’Ivoire

Arbuscular mycorrhizal fungi (AMF) are important plant symbionts, yet the infective potential and field-scale variability of indigenous AMF associated with plantain remain poorly documented in Côte d’Ivoire. We characterised AMF in three major plantain-producing fields (Site 703, 704, and 708) in Central-western Côte d’Ivoire using 40 rhizosphere samples collected at 0–30 cm depth. Soil physicochemical properties, most-probable-number (MPN) infective propagules, trap-culture spore density and viability, root colonisation, and morphology-based richness were quantified. Independent MPN estimates were compared on the logarithmic scale using standard errors reconstructed from their 95% confidence limits, followed by Holm adjustment. Site 703 had 5,400 infective propagules per 30 g of soil and exceeded site 704 by 19.29-fold (95% CI for the ratio 3.56–104.36; Holm-adjusted p = 0.0018) and site 708 by 10.00-fold (1.85–54.11; p = 0.0150); sites 704 and 708 did not differ (p = 0.4458). Total trap-culture spore density varied only from 88.23 to 100.35 spores g−1 (between-site CV = 6.52%), and 56.3–60.0% of spores were viable. Root colonisation frequency remained high (90.91–100%; CV = 5.41%), whereas whole-root intensity (24.73–76.36%; CV = 52.92%) and whole-root arbuscular abundance (18.05–68.82%; CV = 60.63%) were substantially more variable. Eleven pooled morphospecies representing four genera were identified, with Glomus accounting for six taxa. The convergence of high MPN, colonisation intensity, and arbuscular abundance identifies site 703 as the strongest candidate source for inoculum isolation. The data demonstrate the presence of infective indigenous AMF but do not establish plant growth effectiveness or identify causal edaphic drivers.