Abstract: 【Objective】The objective of this study is to investigate the resistance level of Eleusine indica to glyphosate, a 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase inhibiting herbicide.【Method】Seven E. indica populations were collected from different orchards or ridges of different areas in Guangzhou, Huizhou, Meizhou in Guangdong Province where glyphosate had been continuously applied for different years. The resistance level of E. indica to glyphosate was assessed by whole plant assay. The differences of shikimic acid content and chlorophyll fluorescence parameters (Fv/Fm and α) in the most resistant and susceptible populations were measured by ultraviolet spectrophotometer and Dual PAM-100, respectively.【Result】The relative resistance index of E. indica population which collected from Yangcun in Huizhou was 11.0. The result obtained in laboratory was agreed with the real fact in fields. Furthermore, E. indica collected from Yangcun accumulated lower level shikimic acid in 7 days after glyphosate treatment, while that one collected from Panyu in Guangzhou was the most susceptible population accumulated 9.1 times shikimic acid of Yangcun population on 7 th after 1 845 g a.i./hm2 of glyphosate application. The results from the analysis of chlorophyll fluorescence parameters showed that the values of Fv/Fm and α in leaves of E. indica from Yangcun were generally higher than that one from Panyu in Guangzhou, and the values of both parameters in leaves of E. indica from Panyu were declined to zero on 5 th after glyphosate treatment. 【Conclusion】 E. indica which collected from orchard or ridge has apparently evolved resistance to glyphosate, and Yangcun population is the most resistant one, which accumulated lower level of shikimate acid and photosynthesis system worked well basically after glyphosate treatment.

Key words: Eleusine indica, glyphosate, resistance level, chlorophyll fluorescence