5. Conclusions
This study showed that exogenous SA (10mg L-1) could promote the degradation of three pesticides in nutrient solution and suppress the accumulation of three pesticides in roots and leaves. Noteworthy, the role of SA in reducing pesticide residues was related to the accumulation sites of cucumber plants. Through the calculation of root concentration factor (RCF) and translocation factor (TF), it was found that exogenous SA (10mg L-1) significantly weakened the absorption capacity of roots to the three pesticides. Whereas, the translocation capacity of the three pesticides in cucumber plants were enhanced with three concentrations of SA supplementation. According to our study, single root exposure of three pesticides all caused phytotoxicity, which showed that the plants biomass decreased, chlorophyll synthesis was inhibited, proline accumulation increased, lipid peroxidation was promoted, and the activities of antioxidant enzyme (SOD, APX and GST) was destroyed, respectively. However, these adverse effects could be alleviated by supplementing with appropriate concentration of exogenous SA (1mg L-1 and 10mg L-1). This present study provided evidence that SA could reduce the accumulation of pesticides in plants and provided a basis for the application of exogenous SA in agricultural production. However, the exact interaction mechanism between pesticides and SA in plants needs to be further elucidated.
Acknowledgement
This work was supported by National Natural Science Foundation of China (31801781), Guangxi Special Fund Project (AA17204043-1), Natural Science Foundation of Shandong Province (ZR2018BC038), and National Key R&D Program of China (2016YFD0200206).