Distribution and accumulation dynamics of fungicide azoxystrobin in the soil-plant system

Azoxystrobin is a widely used fungicide belonging to the strobilurin group, primarily employed to control a range of fungal diseases in crops, including pepper (Capsicum annuum L.). As a systemic pesticide, it effectively inhibits mitochondrial respiration in fungi, thereby preventing their growth and spread. However, concerns have emerged regarding its environmental persistence and potential bioaccumulation in soil-plant systems. This study conducted a field study and utilized HPLC-MS/MS for sample analysis, investigating the distribution and accumulation dynamics of azoxystrobin in the soil-plant system, with a focus on its behavior in different soil depths and plant tissues. The results show that pesticide concentration in the shoots remained consistently low throughout the observation period. In contrast, the concentration in roots gradually increased over time, with a peak observed in the top soil around the 10th day (16.56 mg/kg), followed by a rapid decrease to 1.44 mg/kg by the 14th day after application. The pesticide concentration in the subsurface soil remained relatively stable, reaching 0.91 mg/kg by the 35th day. The percentage distribution of pesticides in different parts of the system was as follows: top soil > subsurface soil > roots > shoots. The biological concentration factor (BCF) was greater than 1 during the early and middle-late growth stages, and both the biological accumulation coefficient (BAC) and translocation factor (TF) remained consistently below 1. This study highlights the role of the top soil as a primary pesticide reservoir and suggests limited translocation efficiency from roots to shoots. This pattern of accumulation could have significant implications for environmental health by indicating potential risks of pesticide persistence in the soil, emphasizing the need for further research on optimizing agricultural practices to mitigate pesticide accumulation in the environment.