Graphene quantum dots-induced physiological and biochemical responses in mung bean and tomato seedlings

Different physiological and biochemical responses in mung bean (Vigna radiata L.) and tomato (Solanum lycopersicum L.) seedlings induced by graphene quantum dots (GQDs) (250–1500 mg L−1) were studied. Results showed that both seeds exposed to GQDs can still germinate normally. However, the growth of the seedlings after germination was adversely affected by the GQDs, and mung bean was more sensitive than tomato. In hydroponic experiments, the appropriate concentration of GQDs enhanced the accumulation of chlorophyll in mung bean (250–1250 mg L−1) and tomato (250–500 mg L−1) seedlings after exposure for 2 weeks. High concentrations of GQDs (1000–1500 mg L−1) led to an increase in the H2O2, malondialdehyde (MDA), proline, glutathione (GSH) levels, as well as increased catalase (CAT) and glutathione reductase (GR) activities in seedlings of both species. In addition, the migration of GQDs into plants was observed. Results showed that high concentrations of GQDs had an adverse effect on the growth of both plants, and mung bean seedlings were more sensitive than tomato seedlings. In addition, the problem of nanocontamination was suggested and the resulting food safety problems warrant further investigation.