The Detecting Methods Of Sensitivity For Important Weeds To Glyphosate In Soybean Fields

To develop the methods for detecting the sensitivity of weeds to glyphosate, and to clear thesensitivity of some important weeds to glyphosate, this research take the Echinochloa indica andDigitaria sanguinalis et al. as material, detected the sensitivity of these weeds to glyphosate by thephysiological and biochemical indicators in the greenhouse and field condition. Then use the effectivemethods detected the sensitivity of nine goosegrass biotypes to glyphosate in China. The main results asfollows:1. The visual observation method can detect the sensitivity of those five weeds species accurately inboth greenhouse and field condition. The greenhouse study shows that the GR₅₀of those weedsdetected by the visual observation method were not significant different than detected by the freshweight except the D. sanguinalis and Amaranthus retroflexus, and the order of the GR₅₀was thesame which was D. sanguinalis> A. retroflexus> Eleusine indica> E. crusgalli> Setaria viridis.The GR₅₀of those five weeds detected by the visual observation method was in the scope of theresult detected by the visual measure in the field condition which was D. sanguinalis> E.crusgalli> S. viridis> E. indica> A. retroflexus.2. Shikimate accumulations in the five weeds were increased after treated with glyphosate andpositive correlation to the dosages and growth stage. The shikimate content in different weeds wassignificant different. The logistic model can detect the GR₅₀of five weeds and distinguish thesensitivity of E. crusgalli and D. sanguinalis plants in difference growth stage. The shikimatecontent can reach to6745.3μg/g in A. retroflexus while1050.2μg/g in E. crusgalli. The sensitivityto glyphosate from low to high was E. indica, D. sanguinalis, E. crusgalli, Chenopodium album, A.retroflexus which was different with the result detected by fresh weight method. The shikimateaccumulation can reach to8379.9μg/g in S. viridis while2368.5μg/g in E. crusgalli in fieldcondition and the GR₅₀of E. indica, D. sanguinalis and A. retroflexus was in the scope of the resultdetected by the visual method.3. The relatively content of chlorophyll in the leaves of five weeds was decreased after treated withthe glyphosate and negative correlation to the dosage. The relatively content of chlorophyll in theleaves of different weeds was related to the growth stage; Chlorophyll method can reflect thesensitivity of three weeds in field condition. The SPAD values on these weeds were range from30to50. The SPAD values of monocotyledonous weeds decrease after treatment, it range from0to5,while the SPAD values more than15in the leaves of dicotyledonous weeds after7days treatment.The order of the GR₅₀was E. crusgalli> D. sanguinalis> S. viridis.4. The sensitivity of biotypes Guangzhou （GZ） and Anyang （AY） decreased significant. The shikimateaccumulation in biotype Feicheng （FC） was2.1and1.2times more than the biotypes GD, AY,respectively8days after treated with glyphosate of1640g ai/ha. The different control goosegrassevolved in the orchards. The GR₅₀and the shikimate accumulation of six soybean biotypes have not significant difference.