Abstract:

The aim is to clarify the glyphosate resistance level of Digitaria sanguinalis and Amaranthus retroflexus from farmland in Guizhou, and to provide a theoretical basis for the resistance management of weeds. 32 populations of D. sanguinalis and 30 populations of A. retroflexus were used as experimental materials. The whole plant pot method was used to determine the fresh weight inhibition rate of glyphosate on the aboveground parts of weeds after two weeks of drug application. The results showed that: the sensitivity of D. sanguinalis population in Liuhe village of Qixingguan District of Bijie was the lowest, with ED₅₀ value of 16.23 g a.i/hm², and the relative resistance ratios of other populations ranged from 1.0 to 5.3, 12 populations of D. sanguinalis were in the sensitive stage, 17 populations had low level of resistance, and 1 population had medium level of resistance. The ED₅₀ value of A. retroflexus population in Shuangping township of Hezhang County was the lowest, with ED₅₀ value of 15.38 g a.i/hm², the relative resistance ratios of other populations ranged from 1.0 to 9.0, 12 populations of A. retroflexus were in the sensitive stage, 14 populations had low level of resistance, and 4 populations had medium level of resistance. In conclusion, different populations of D. sanguinalis and A. retroflexa have different degrees of resistance to glyphosate in Guizhou Province, but most of them are in the sensitive stage or low drug resistance level.

Key words: Digitaria sanguinalis, Amaranthus retroflexus, glyphosate, drug resistance