Graphitic carbon nitride (g-C₃N₄) alleviates cadmium-induced phytotoxicity to rice (Oryza sativa L.)

In the present study, graphitic carbon nitride (g-C₃N₄) was synthesized in a tube furnace and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR). Different concentrations (0-200 mg/L) of g-C₃N₄ were prepared in nutrient solution amended with or without 20 mg/L CdCl₂ for the greenhouse study. Rice seedlings were exposed to g-C₃N₄ and Cd for 20 days. Our results suggest that 200 mg/L g-C₃N₄ significantly increased the fresh weight and root and shoot length as compared with the control, and notably alleviated Cd-induced toxicity. The addition of 200 mg/L g-C₃N₄ significantly reduced the root and shoot Cd content by approximately 14% and 23%, respectively. In addition, 200 mg/L g-C₃N₄ significantly elevated the nitrogen content and decreased C/N ration in rice shoots; most importantly, it alleviated Cd-induced nitrogen reduction. Our findings demonstrated the potential of g-C₃N₄ in regulating plant growth and minimizing the Cd-induced phytotoxicity, and shed light on providing a new strategy to maintain heavy metal contamination in agriculture using a low-cost and environmental friendly NMs.