Hexaploid oat genetic variability was compared in populations treated with physical and chemical mutagens by making a field evaluation of vegetative cycle. Experiments were carried out in two agricultural years in Pelotas, RS (1997/98 and 1998/99). Seeds were irradiated at the UFPel OncoloGy Center, with a dose rate of 0.25Gy min-1. The total absorbed doses for the physical mutagen were 100, 200 and 400Gy and, for the chemical mutagen 0.5, 1.5 and 3.0% per treatment of 1,200 seeds, in each evaluated genotype. A difference in efficiency between mutagens was detected. The physical mutagen was always superior to the chemical mutagen, regardless the generation evaluated, providing a higher increase in the number of phenotypic classes, either leading to a reduction or increase in the number of days between emergence and flowering. The genotypes showed a differential sensitivity to the doses of tested mutagens, indicating a range of treatment efficiency in altering the genetic variability either for early or late vegetative cycle. In general, the results pointed to a decrease in the character vegetative cycle when an increase in the mutagen dose was applied. The study of populations UPF 16 on the doses 100 and 200Gy subjected to treatment with the physical mutagen pointed to a higher degree of genetic divergence and dominance for the character vegetative cycle.
Avena sativa L.; 60Co; EMS; vegetative cycle; genetic variability
