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• Drought stress reduced AMF colonization and both the quantitative and qualitative yield of soybean oil. • ZnO-NPs combined with AMF improved AMF colonization under severe drought compared to AMF alone. • ZnO-NPs and AMF exhibited synergistic effects by enhancing physiological traits, reducing oxidative stress, and increasing seed yield. • ZnO-NPs and AMF increased oil content by 79% and oil yield by 89%. • Drought stress reduced oil quality, but ZnO-NPs and AMF improved it by increasing unsaturated fatty acids. The increasing frequency and intensity of drought stress, exacerbated by climate change, pose significant threats to agricultural productivity and food security. In this context, this study investigates the effects of zinc oxide nanoparticles (ZnO-NPs) and Myco-Root-a proprietary blend of three distinct mycorrhizal fungal species-on the yield and oil quality of soybean ( Glycine max ) under drought stress. By exploring innovative strategies, this research aims to enhance agricultural resilience and promote sustainable food production in challenging environmental conditions. Utilizing a randomized complete block design over two years (2021–2022), the experiment included 12 treatments with three levels of drought stress (optimal irrigation (MAD 20 ), moderate water deficit (MAD 50 ), and severe water deficit (MAD 80 )) and four fertilizer management strategies (control, ZnO-NPs (200 mg L⁻¹), arbuscular mycorrhizal fungi (AMF), and a combination of both). The results showed that drought stress reduced colonization, whereas the combined application of ZnO-NPs+AMF enhanced colonization by 10% relative to AMF alone. Additionally, under MAD 20 conditions, the combined treatment of ZnO-NPs+AMF significantly increased nitrogen, phosphorus, potassium, and zinc uptake by 82.61%, 100.49%, 94.78%, and 143.11%, respectively, compared to severe drought stress conditions without fertilization. This treatment also increased proline and soluble carbohydrates under severe drought conditions by 77.29% and 58.75%, respectively, compared to the control. Furthermore, the activity of antioxidant enzymes such as ascorbate peroxidase, guaiacol peroxidase, and catalase increased by 85.92%, 111.18%, and 80.13 respectively, reducing oxidative stress markers such as malondialdehyde (51.27%) and hydrogen peroxide (63.44%) compared to untreated conditions. In terms of both oil quantity and quality, the combined treatment of ZnO-NPs+AMF under MAD 20 conditions increased linoleic and linolenic acid concentrations by 60.75% and 43.91%, respectively, while decreasing palmitic and stearic acid concentrations by 50.45% and 24.88%, respectively. These changes resulted in a 145.47% increase in seed yield and an 24.32% increase in oil content compared to MAD 80 conditions without treatment. Additionally, when compared to severe drought stress without fertilization, the application of ZnO-NPs+AMF under MAD 20 enhanced the iodine value by 9.7%, while the saponification number under MAD 80 without fertilization increased by 3.2% relative to the control. Furthermore, the combined application of ZnO-NPs+AMF under optimal irrigation conditions resulted in an 41.04% reduction in the acid value compared to drought stress without fertilizer application. Overall, these findings suggest that the combined use of ZnO-NPs and AMF can serve as an effective strategy to improve crop performance and oil quality under drought stress conditions. This approach enhances plant resilience to climate change, improves agricultural productivity, promotes food security, and supports the sustainability of agricultural systems.
Haghaninia et al. (Thu,) studied this question.