Genetic variability induced by chemical and physical mutagenic agents in oat genotypes

Objective of the present work was to compare the magnitude of genetic variability generated in hexaploid oat genotypes treated with two mutagenic agents: physical versus chemical. The physical agent was nearly always superior to the chemical agent, regardless of the evaluated cross or generation, providing a larger number of phenotypic classes of shorter plants. The mutant genotypes indicated a differentiated sensitivity to doses of the applied agents. This fact shows the effic iency of these agents in altering the genetic variability of this trait upwards (high height) as well as downwards (short height). I n general, data pointed to a decrease in the trait plant height under increasing agent doses. The largest degree of genetic divergence and dominance for the new dwarfing genes was obtained by doses 100 Gy and 0.5%, respectively, of mutagenic physical and chemical agents applied to UFRGS 10 genotype in the M 2 generation.