Ryegrass populations resistant to ALS enzyme inhibitors have increased rapidly in cultivated fields. For resistance management, are necessary resistance inheritance studies, which allow us to understand the evolution of resistance, the genetic structure of the population and the dynamic adaptation of resistant biotypes. This study aimed to identify the type of inheritance, the number of genes involved and the degree of resistance of ryegrass biotypes, homozygous and heterozygous resistant iodosulfuron. From the selection of resistant biotypes homozygous (R) and susceptible homozygous (S), crosses were performed (R x S) to obtain the F1 and these crossed to obtain F2, and backcross were held between F1 plants and their parents male and female resistant (RCr) and sensitive (Rcs). The F1 seed, F2, RCr, RCs and parents were sown in trays and evaluated, with application of iodosulfuron, as to their susceptibility or resistance. F1 plants and parents were treated with increasing doses of the herbicide. The control of these plants by iodosulfuron was made by way of notes (0 to 100), referring to the symptoms of intoxication and dry matter accumulated shoot. The male or female parents passed on the trait to offspring, which is 100% resistant, indicating dominant gene resistance. The F2 generation presented segregation 3:1 resistant/susceptible, confirming the dominance of feature. The F1 plants dominance test showed that the resistant homozygous plants and heterozygous present similar resistance level. We conclude that the ryegrass resistance to iodosulfuron is encoded by nuclear dominant gene with complete dominance.
Lolium spp.; genetics; herbicide