Abstract
Mutagenic efficiency was defined by Konzak et al. in 1965 as the ratio mutation/biological damage factor. His formula considers that mutagens always causes damage, but it has been shown that low doses of gamma-rays stimulate seedling growth. In this situation a negative value for damage is obtained with a negative mutagenic efficiency rate. This has no biological interpretation and the notion of range for mutagenic efficiency variation is also lost. An alternative index for mutagenic efficiency, which is a modification of the Konzak et al. 1965 formula, is proposed [mutation factor (1-damage/100)]. This index is more general, with known limits and positive results, thus overcoming some of the limitations found in the original formula.
Highlights
According to Gustafsson and Gadd (1966), De Vries was, in 1901, the first scientist to use artificial mutation in genetic breeding
The highest and the lowest points correspond to the Msp/I from treatment with the value 6.33/3.18 and treatment with the value 4.6/-2.68, respectively
At the lowest point the effect of the stimulus of a negative I is observed. This situation precludes an understanding of the range of efficiency variation
Summary
According to Gustafsson and Gadd (1966), De Vries was, in 1901, the first scientist to use artificial mutation in genetic breeding. Konzak et al (1965) formulas always consider mutagenic substances as damage-causing agents and, the percentage of loss will be always positive. From Konzak et al (1965) original formula: The mutant efficiency can be evaluated by the ratios Msp/L, Msp/I and Msp/S (Konzak et al, 1965), where: 2001, Sociedade Brasileira de Melhoramento de Plantas
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