Residue and distribution of triforine in different cultivars and fruit periods of watermelon under field conditions.

The dissipation of triforine in the immature and mature fruit periods was investigated under field conditions. Residue levels of triforine in watermelon were determined by gas chromatography with an electron capture detector (GC-ECD). The decline curves of triforine residues in the watermelon corresponded with first-order kinetics. The half-lives of triforine in Dark Belle and Shiny Boy were 2.10-2.57 days and 2.31-2.67 days respectively. Meanwhile, the half-lives of triforine in the immature and mature fruit periods were 1.69-2.04 days and 2.89-3.85 days, respectively. In the terminal residue experiment, the terminal residues of triforine in the watermelon flesh and peel were below 0.01 mg/kg to 0.05 mg/kg and 0.03 mg/kg to 0.36 mg/kg, respectively. The dissipation rates of triforine varied in different cultivars of watermelon, and even in the same cultivar, the half-lives of triforine significantly varied in the different fruit periods. Although triforine is a fungicide within the suction, the terminal residues in the peel and flesh were very significant.