Uptake,Translocation Of Triadimefon In Different Crops And Various Soil Types

Triadimefon is a systemic broad-spectrum fungicide widely used in agriculture production in China.In practice,spraying and seed coating agent are used as the main application methods of triadimefon.The residual triadimefon is easily absorbed and enriched by crops,which poses a potential threat to food safety.In this paper,the uptake,translocation and bioconcentration characteristics of triadimefon in wheat as well as the uptake pathway and its distribution in subcellular components were investigated by hydroponic experiments.The key control factors affecting the absorption of triadimefon in different crop roots were analyzed in combination with its uptake,translocation and bioconcentration characteristics in five common crops.In addition,the adsorption in different soils and wheat uptake were also measured in the study.The main results were summarized as follows:1.Triadimefon could be transported upward through the stems to the leaves and accumulated mainly in the leaves after being absorbed by wheat roots.The uptake of roots reached equilibrium after 72 h,and the accumulation of triadimefon in the leaves increased continuously with time.The transport of triadimefon from stem to leaf was easier than that from root to stem.2.Being uptook by wheat roots apoplast,the triadimefon was mainly distributed in the cell fluid of the root and stem cells.It was easy for triadimefon to transport upward to the leaves because it was not easily retained by the solid phase component.And the solid phase components of the leaf cells could continuously enrich it from the cell fluid,resulting in the stronger ability of leaves to enrich triadimefon.3.Triadimefon could be transported upward through the stems to the leaves in cucumber,tomato,wheat,pepper and corn plants,and the transfer from root to stem was more difficult than that from stem to leaf.Moreover,the LCFs of different crops were much higher than RCFs.It indicated that the leaves were the main accumulation site of triadimefon.The uptake and bioconcentration capacity order of triadimefon in different crops was: cucumber > pepper > tomato > corn > wheat.Transpiration rate and root specific surface had the significant positive relationship with the uptake and bioconcentration of triadimefon by root,which were the main and secondary factors,respectively.The root protein content had no significant effect on it.4.The soil adsorption capacity sequence of triadimefon in five soils was Wuxi < Jinhua < Xiaoshan < Helen < Fuyang.Triadimefon was difficult to be adsorbed in Wuxi soil,while it was slightly difficult to adsorb in Halun soil.Soil organic matter content and cation exchange capacity(CEC)were the main and secondary factors affecting the soil adsorption of triadimefon,respectively.The Freundlich affinity coefficient(Kfads )was significantly positively correlated with organic matter content and CEC.The uptake and accumulation of triadimefon in wheat plants was significantly positively correlated with in situ pore water concentration,but not with soil concentration.The concentration in situ pore water could be used to evaluate the uptake of triadimefon by wheat plants in the soil more reasonably.This study explored the uptake and accumulation mechanism of triadimefon in wheat and revealed the key control factors that affected the uptake and bioconcentration of triadimefon in different crops.These conclusions could provide basic data for the risk assessment of triadimefon as well as the pesticide reduction application technology,which are of great practical significance for achieving the strategic goal for zero-growth in pesticide usage.