Glyphosate is a non-selective herbicide used to control weeds. Azevem plants, which are tolerant to glyphosate, have been identified in Rio Grande do Sul, where they are rapidly becoming predominant. The objective of this work was to identify inheritance type, number of genes conferring resistance, and the degree of resistance in azevem plants. Reciprocal crossings between sensitive and resistant plants have been carried out to obtain F1 seeds which were crossed among themselves to obtain F2 plants .Herbicide containing 720 g ha-1 was applied on the F1, F2, RCr, Rc and parent plants to estimate segregation. To evaluate the degree of resistance of the F1 plants, resistant and sensitive parents were sprayed with increasing rates of glyphosate (0, 360, 720, 1.440 and 2.880 g ha-1). F1 plants showed intermediate response to the resistant and sensitive biotypes, indicating that allelic interaction is of the incomplete dominance type. F2 plants showed a tendency for segregation 3:1, indicating that resistance to glyphosate is controlled by a semi-dominant gene.
herbicides; hybridization; EPSP-inhibitors
