The pollution of micro/nanoplastics in the natural environment is becoming increasingly serious, but the potential effects of nanoplastics on crops remain unclear. In the present study, the effects of polystyrene nanoplastics (PS-NPs) with a particle size of 80 nm on the chlorophyll content, antioxidant enzyme activity, and nutritional quality of Allium sativum L. were explored via hydroponic culture. The results showed that the chlorophyll contents in leaves of A. sativum treated with PS-NPs were significantly lower than those in the control, indicating that the synthesis of chlorophyll was inhibited. The superoxide dismutase (SOD), ascorbate peroxidase (APX) activities, and proline contents in leaves of A. sativum initially increased but then decreased with the increase in ρ(PS-NPs). The activity of guaiacol peroxidase (POD) increased with the increase in ρ(PS-NPs) for 10 days of treatment; however, it was inhibited for 20 days of treatment. The malondialdehyde (MDA) content increased with the rise in ρ(PS-NPs). When ρ(PS-NPs) increased to 100 mg·L-1, the MDA content in leaves of A. sativum increased by 43.24% and 89.70% for 10 and 20-day treatments, respectively, compared with those in the control. Meanwhile, the contents of soluble protein, soluble sugar, and vitamin C were higher than those in the control for 10-day treatments; however, the vitamin C content decreased by 26.53% after 20 days of treatment. These results indicated that PS-NPs had a significant oxidative stress on A. sativum, and a high concentration of PS-NPs stress would have deleterious effects on the nutritional quality of A. sativum.
Keywords: Allium sativum L.; antioxidant enzymes; nanoplastics; nutritional quality; physiology.