Absorption, translocation, and accumulation of the fungicide triadimefon in Pak choi (Brassica rapa var chinensis), pepper (Capsicum annuum) and cucumber (Cucumis sativus)

Abstract

Abstract Triadimefon is a typical systemic fungicide, which is widely used in disease management of powdery mildew, rust disease, and southern blight. In this study, we profiled the absorption, translocation, and accumulation in three representative vegetable crops (Pak choi, cucumber, and pepper) by measuring fungicide residue after over-application. The fungicides were applied through entire-plant spraying (EPS), root-irrigation (RI), and middle-leaf-daubing (MLD). The half-life of triadimefon depends on the application method and plant species. The half-life was 5.42 d (Pak choi), 6.86 d (cucumber), and 6.73 d (pepper) in EPS, while it was 4.39 d (Pak choi), 6.30 d (cucumber), and 5.98 d (pepper) in RI. In the treatment of EPS, triadimefon is translocated both upward/outside and downward/inner-side from the daubed leaves in all the three vegetable crops. And the transfer amount in each organ reached a peak at the 2nd day after the fungicide application. In Pak choi, mesophyll deposited more fungicide than petiole; in cucumber and pepper, leaves deposited the biggest amount of triadimefon (about 0.3–0.5 mg·kg− 1), which is followed by stems. Roots and fruits accumulated the least triadimefon. Moreover, triadimefon can impact chlorophyll, root activity, and the activity of superoxide dismutase and catalase in Pak choi, indicating its potential as a plant growth regulator. These studies above provide new information to apply triadimefon safely and efficiently in production of Pak choi, cucumber, and pepper.