Causal Analysis Between Rice Growth and Cadmium Accumulation and Transfer under Arbuscular Mycorrhizal Inoculation

Cadmium (Cd) contamination in rice has been a serious threat to human health. To investigate the effects of arbuscular mycorrhizal fungi (AMF) on the Cd translocation in rice, a controlled pot experiment was conducted. The results indicated that AMF significantly increased rice biomass, with an increase of up to 40.0%, particularly in root biomass by up to 68.4%. Notably, the number of prominent rice individuals also increased, and their plasticity was enhanced following AMF inoculation. AMF led to an increase in the net photosynthetic rate and antioxidant enzyme activity of rice. In the AMF treatment group, the Cd concentration in the rice roots was significantly higher (19.1%‒68.0%) compared with that in the control group. Conversely, the Cd concentration in the rice seeds was lower in the AMF treatment group, indicating that AMF facilitated the sequestration of Cd in rice roots and reduced Cd accumulation in the seeds. Path coefficients varied across different treatments, suggesting that AMF inoculation reduced the direct impact of soil Cd concentration on the total Cd accumulation in seeds. The translocation of Cd was consistently associated with simultaneous growth dilution and compensatory accumulation as a result of mycorrhizal effects. Our study quantitatively analyzed this process through path analysis and clarified the causal relationship between rice growth and Cd transfer under the influence of AMF.