Eco-Friendly Synthesis of Zirconia Nanoparticles Using Sonchus asper Extract: A Sustainable Approach to Enhancing Chinese Cabbage Growth and Remediating Chromium-Contaminated Soil

Chromium (Cr) contamination poses severe risks to plant health and soil quality, requiring sustainable remediation methods. This study explored the synthesis of zirconia nanoparticles (PF-ZrO₂ NPs) from <i>Sonchus asper</i> extract and assessed their potential to alleviate Cr toxicity in Chinese cabbage (<i>Brassica rapa</i> var. pekinensis). The characterization of nanoparticles was performed through XRD, SEM, and FTIR analyses, confirming their crystalline nature, structure, and surface chemistry. The results indicated significant declines in plant growth, chlorophyll content, biomass, and nutrient uptake under Cr stress (treatments T2 and T4), accompanied by elevated oxidative stress indicators (H₂O₂, MDA) and Cr accumulation. The application of PF-ZrO₂ NPs (T3 and T5) notably reduced shoot Cr concentrations (by 58.94% and 35.90%) and improved the chlorophyll level (by 5.41% and 14.41%). Additionally, nanoparticles increased antioxidant enzyme activity (SOD, POD, CAT) and improved soil properties (pH, cation exchange capacity, nutrient retention). These findings suggest green-synthesized PF-ZrO₂ NPs are effective, environmentally friendly candidates for Cr remediation in contaminated soils.