Effect of silver nanoparticles and pathogenic fungi, on seedling growth of Acacia senegal and Acacia mellifera under drought stress

Drought stress is a significant abiotic factor limiting seedling growth, development and biomass production. However, silver nanoparticles (AgNPs), known for their ability to inhibit pathogenic fungi, conidiation and virulence, may mitigate these effect and enhance plant growth and yield under drought conditions. This study investigated the effects of drought stress and AgNPs (0, 25, 50 and 75 mg/L) on Acacia senegal and Acacia mellifera seedlings growth exposed to Rhizoctonia solani (pathogenic fungal). A split-plot experimental design was employed with three blocks and three replicates, incorporating drought stress and AgNPs treatments for each species. The results demonstrated that drought stress and AgNPs significantly (P < 0.05) improved seedling growth in both species, with 75 mg/L concentration, yielding the greatest benefits. This treatment enhanced seedling vigor indices and biomass production compared to control. Moreover, AgNPs exhibited strong antifungal activity, reducing R. solani infection and improving overall plant health under drought stress. Notably, the highest height was recorded at 75 mg/L AgNPs, with increase of 60.63% and 152.86% in the well-watered seedlings of A. mellifera and A. senegal, respectively. The study concludes that biosynthesized AgNPs effectively promote seedling development, and resistance to fungal infections in Acacia species, offering a promising strategy to enhance plant resilience under drought conditions.