Combined effects of arbuscular mycorrhizal fungi and selenium nanoparticles on photosynthesis and nutritional quality of Ocimum basilicum L

Abstract

Although selenium nanoparticles (SeNPs) and arbuscular mycorrhizal fungi (AMF) are each known to enhance plant growth and stress tolerance, their combined application in medicinal herbs remains largely unexplored. This study evaluates how the concurrent action of applied SeNPs and AMF root colonization reprograms photosynthetic metabolism, antioxidant defense, and secondary metabolite pathways in sweet basil (Ocimum basilicum L.). In a factorial greenhouse experiment with four treatments (control, AMF, SeNPs, and AMF + SeNPs), the combined treatment markedly enhanced fresh and dry biomass accumulation by 72.8% and 96.2%, respectively. The treatments yielded strong additive benefits for gas exchange and pigment accumulation, where the combined application markedly enhanced net photosynthetic rate by 65.5% and chlorophyll level by 75.7%. This was in line with additively suppressed photorespiration, reflected in a 57.9% and 62.1% decline in glycolate oxidase and hydroxypyruvate reductase activity, respectively. The AMF-SeNPs interaction also enhanced phenylpropanoid-derived antioxidants (individual and total phenolic acid and flavonoids) amplifying total antioxidant capacity by 38.2%. By integrating biological and technological interventions, this study establishes an eco-efficient framework that maximizes both crop productivity and bioactive medicinal quality through improved redox homeostasis. While these greenhouse results are promising, future field trials with varied dosages remain essential to confirm the practical scalability of this combined approach.