Abstract:

Water management and arbuscular mycorrhizal fungi (AMF) are the key factors affecting cadmium uptake, distribution and antioxidant defense system in rice roots. It is important to explore the relationship and mechanism of the three factors to guide the safe production of rice fields. In this study, with rice ‘Hemeizan No.2’ and AMF Rhizophagus irregularis as experimental materials, under different water management conditions, the effects of AMF on cadmium uptake, distribution and effects of root antioxidant defense system in rice were studied under different cadmium pollution concentrations (0.2, 1.0, 5.0 mg/kg). The results showed that under the condition of non-mycorrhizal treatment, the cadmium content of rice under different water management conditions increased with the increase of soil cadmium content. Especially compared with long-term flooding, dry and wet alternations significantly increased the effective cadmium concentration in soil, promoted cadmium uptake in rice roots and increased cadmium content in straw. However, under different water management conditions, the addition of AMF increased the pH of different cadmium-contaminated soils, reduced the availability of soil cadmium, inhibited the transfer of cadmium from rice roots to the above-ground part, and thus reduced the cadmium content of straw and the enrichment effect of rice on cadmium. Especially under the condition of moderate cadmium pollution, the addition of AMF increased the activities of peroxidase (POD) and superoxide dismutase (SOD) in rice roots, and reduced the absorption of cadmium in rice roots (alternating dry and wet) and the distribution of cadmium in rice root subcells. Therefore, the addition of AMF can effectively reduce the accumulation of cadmium in the above-ground part of rice under the water management conditions such as long-term flooding and alternating of wetting and drying.

Key words: arbuscular mycorrhizal, cadmium, subcells, antioxidant defense system, water management, rice, cadmium pollution