Early Vegetative Growth of Themba Oil Palm (Elaeis guineensis Jacq.) Seedlings under Graded AMF Formulation Rates

Abstract

Arbuscular mycorrhizal fungi (AMF) are widely used as biological inputs to improve nutrient acquisition and plant growth. However, their effectiveness may vary depending on inoculum rates, host genotype, and nursery conditions. This study evaluated the early vegetative response of Themba oil palm seedlings to graded rates of a commercial arbuscular mycorrhizal fungi (AMF) formulation. Design/ methodology/ approach: A nursery experiment used a Completely Randomized Design with five replications and six formulation rates (0, 5, 12.5, 15, 17.5, and 20 g seedling⁻¹). Plant height, leaf length, and leaf number were recorded weekly for four weeks after inoculation. Findings: AMF formulation rate did not significantly affect plant height (p = 0.276), leaf length (p = 0.129), or leaf number (p = 0.670) at week four. The 20 g treatment had the highest mean, but the differences were not statistically significant. Polynomial regression was descriptive (R² = 0.54–0.88) and did not establish an optimum rate. Research limitations/implications: The four-week duration, the absence of root colonization and tissue nutrient measurements, and the lack of a carrier/product-only control limit the attribution of effects specifically to AMF. Originality/value: The study provides preliminary rate-response information for the Themba variety and identifies methodological priorities for longer AMF nursery trials.