Silicon-Nanomaterials Enhance Stress Resilience and Early-Maturity of Onions (Allium cepa L.) in Acidic Soils

Silicon-nanomaterials (Si-NMs) have emerged as a revolutionary tool in modern agriculture; however, the collaborative role of Si-NMs in onion crop productivity and expansion in acidic soils remains elusive. We conducted a series of sequential experiments, from seed germination to field trials, over two consecutive cultivation years. Intriguingly, the results revealed that among the differential doses, 1.0 mM L−1 of Si-NMs significantly ameliorated the acid-stress-induced suppression of onion seed germination and seedling growth. Additionally, a selected dose of Si-NMs reduces seedling mortality and improves plant establishment rate with increased photosynthetic performance, bulb properties, and nutritional quality. These stimulatory effects of Si-NMs on onion crop adaptation to acidic soil were associated with reduced ROS accumulation driven by enhanced antioxidant potential, which further increased upon dolomite supplementation. Furthermore, exogenous Si-NMs spray accelerated the early stages of harvestable onion size, accompanied by increased synthesis of IAA and GA3 hormones, suggesting the potential of Si-NMs to enhance farm resilience in acidic soils.