Abstract:The role of flavonoids metabolism in glyphosate phytotoxicity were studied through the effects of glyphosate on secondary metabolism of flavonoids and the relationship between flavonoids and the phytotoxicity of glyphosate. The seedlings of Fagopyrum tataricum were treated with 0.1 mmol/L, 0.3 mmol/L and 1.0 mmol/L of glyphosate, respectively. The result showed that the flavonoids metabolism in F.tataricum seedling was inhibited obviously. The flavonoid contents in seedlings were 58.1%, 65.8% and 76.5% lower than that of the control after 3 d. The treatment of glyphosate enhanced membrane lipid peroxidation which gradually increased following the increase of glyphosate concentration. When F.tataricum seedlings were treated with 0.1 mmol/L of glyphosate, the relative electrical conductivity, malondialdehyde (MDA) content and O-2.yield were 275.4%, 134.1% and 121.7% higher than that of control, showing that the injury of glyphosate happened upon membrane lipid peroxidation process. Treatment with 0.1 mmol/L rutin as a flavonoids matter after 0.3 mmol/L glyphosate treatment caused the decrease of glyphosate injury obviously. The electrolyte leakage, MDA content and O-2.yield in F.tataricum seedlings decreased by 34.2%, 51.1% and 33.9% respectively. The decrease in flavonoids contents may relate to tissue injury of F.tataricum by glyphosate.