Genetic variability increase by gamma irradiation of soybean seeds.

The increase of genetic variability by the appearance of new genes of agronomic interest may be favored by the use of gamma radiation. The objective of this study was to evaluate different doses of gamma irradiation on dry seeds of VX04-5692 soybean line, aiming to increase the genetic variability and, with this, the identification of possible mutant plants. The doses of 0, 50, 150 and 250 Gy of gamma radiation were applied from aCo source. The newly irradiated seeds were sown in the field, giving rise to the M1 cycle. Selected plants originated the M2 cycle. The number of seedlings was counted on the 21st day after sowing. Ten plants of each row were identified and evaluated for the various agronomic characteristics and for chemical composition. The data were submitted to analysis of variance. The F test was applied and the results were presented by boxplots and biplot (canonical variables). There was effect of gamma radiation doses at plant height at full bloom and maturity, number of nodes, pods with one seed and seeds per pod. The use of gamma radiation increases the variability in soybean, with consequent increase in the probabilities of identification of new mutants and gains in the chemical composition, useful for breeding programs that aim at better agronomic performance and gains in oil and protein contents. More satisfactory results in the generation of variability are obtained by the application of gamma radiation on soybean dry seeds between 50 and 150 Gy.