Silicon actively mitigates the negative impacts of soil cadmium contamination on garlic growth, yield, quality and edible safety

Abstract

Potential health risks of cadmium (Cd) in agroecosystems migrating to the human body along the food chain have become a worldwide hotspot issue, but information on phytotoxicity mitigation and product quality and safety assessment of Cd-stressed garlic is still lacking. Thus, based on the response performance of garlic yield and quality to soil pH and Cd level, this study systematically revealed the effects of silicon (Si) on the growth, yield, quality, photosynthesis, fluorescence, antioxidant system, tissue Cd residues and edible safety of Cd-stressed garlic. The results showed that garlic yield and quality decreased with increasing soil Cd levels, while the lower soil pH exacerbated Cd contamination. When exposed to 1.2 mg kg−1 Cd, the bulb yield at pH 5.50 was 5.51% lower than that at pH 6.89, while the Cd residues in the bulb were 8.77% higher. Notably, 0.67∼2.0 g kg−1 Si application enhanced bulb yield (by 12.09%∼39.32%) and quality (e.g., allicin, by 6.67%∼40.00%) and simultaneously reduced Cd absorption, translocation and accumulation (e.g., bioconcentration coefficient, by 13.01%∼86.17%). Si mitigated Cd-induced phytotoxicity mainly by improving root activity, antioxidant enzyme activity, photosynthesis and fluorescence. Si increased the soil pH, which contributed to Cd fixation. These results provide significant theoretical guidance for garlic safety production and heavy metal risk prevention in agroecosystems.