Physiological and biochemical effects of Ti3AlC2 nanosheets on rice (Oryza sativa L.)

Highlights: • Foliar application of Ti₃AlC₂ (MAX phase materials) could inhibit the growth of rice seedlings. • Ti₃AlC₂ could interfere with the immune system of rice seedlings. • Foliar spraying of Ti₃AlC₂ obviously inhibited the stomatal opening and increased the number of trichomes. • Ti accumulation in rice increased with increasing the concentration of Ti₃AlC₂. MAX phase materials are a new type of nanomaterial with wide applications, but the potential effects of MAX phase materials on plants have not been reported. Herein, we selected Ti₃AlC₂ nanosheets as a typical MAX phase material to investigate its potential impacts on rice (Oryza sativa L.) at 0–1000 μg·mL⁻¹. The foliar application of Ti₃AlC₂ at 100 and 1000 μg·mL⁻¹ inhibited the growth of rice seedlings by producing excess reactive oxygen species (ROS). Furthermore, foliar spraying of Ti₃AlC₂ at 100 μg·mL⁻¹ decreased the stomatal aperture (78.6%) and increased the number of trichomes (100%). These responses demonstrated that the application of Ti₃AlC₂ could interfere with the immune system of plants by changing the structure and function of leaves, disturbing the activities of antioxidant enzymes. According to the above results, we concluded that the toxicity of Ti₃AlC₂ nanosheets on plants was mainly caused by the release of titanium ions. This study provides a valuable reference for understanding the impact of MAX phase materials on plants.