Resistance of Soybean Genotypes to Glyphosate

Resistance of ten soybean genotypes (Glycine max) to the herbicide glyphosate was evaluated. The randomized block experimental design was used under factorial scheme 10 x 4 and four replicates. F-actor A Lvas composed of 10 soybean genotypes and factor B of four glyphosate doses. The herbicide was applied when the second trifoliate leaf of the soybean plants Lvas completely developed. The following characters were evaluated: plant intoxication, number of nodes at the main stem, plant height and dry mass. When evaluating plant intoxication either at four days after application (DAA) of the herbicide and at 28 DAA, the conventional genotypes showed statistically higher averages, compared to the glyphosate-resistant genotypes (RR). In evaluations accomplished at 0 DAA or at 28 DAA under 0.0 g e.a. ha(-1), the genotype responses were different for all characters under evaluation, except for the number of nodes at 28 DAA. These differences were attributed to the physiological and environmental effects or to the characteristics of the material itself. At other doses, the behavior of the RR genotypes was superior to that of the conventional ones. Taking into account all characters under evaluation, it can be stated that Valiosa RR, BCR945G110, BCR945G114, BCR892G132, BCR892G140, BCRI067G210, BCR1070G244 and M-SOY 8008RR behaved similarly for glyphosate resistance when subjected to doses up to 2.160 g e.a. ha(-1).