Biosynthesis of Silver Nanoparticles and Its Effects on the Establishment in vitro of Cassava (Manihot esculenta)

Abstract

Cassava (Manihot esculenta) is a staple crop in Belize, yet efficient in vitro propagation remains challenged by microbial contamination and inconsistent explant development. Silver nanoparticles (AgNPs) offer antimicrobial and growth-modulating benefits. This study compared green-synthesized versus commercial AgNPs on the establishment in vitro of cassava var. “white”. Green AgNPs were biosynthesized using Moringa oleifera extract with AgNO₃ and characterized by UV–Vis and FTIR; commercial AgNPs (XFNANO) served as a reference. Nodal explants were cultured on Murashige and Skoog medium with 1 mg/L 6-benzylaminopurine, 1 mg/L α-naphthaleneacetic acid, and AgNPs at 0, 5, 10, and 15 mg/L. After five weeks, shoot and root lengths were recorded. Contamination percentages were also evaluated. Data were analyzed by one-way ANOVA with Tukey’s HSD for parametric cases and Kruskal–Wallis with Dunn’s post-hoc when assumptions failed. Commercial silver nanoparticles significantly enhanced shoot elongation in a dose-dependent manner, with the 15 mg/L treatment producing a mean shoot length of 1.82 ± 3.27 cm compared to 0.12 ± 0.41 cm in the control group (p < .001). Root growth was also stimulated, reaching 0.44 ± 0.90 cm versus 0 cm in controls (p = 0.0003). In contrast, green-synthesized AgNPs inhibited shoot elongation at 5 mg/L, reducing mean shoot length to 0.38 ± 1.19 cm from 2.20 ± 3.70 cm (p < .001), while root length fell to 0.07 ± 0.26 cm compared to 0.76 ± 1.57 cm in untreated plants (p = 0.0002). Nonparametric tests confirmed these trends under non-normal data distributions. The variance ranged from medium to large, indicating robust treatment effects. Commercial AgNPs can promote initial explant growth, while plant-extract–derived AgNPs at tested doses exert phytotoxicity. These contrasting outcomes underscore that nanoparticle source and concentration must be optimized to balance antimicrobial control with plant growth.