Evaluation of the Effect of Different Doses of Physical and Chemical Mutagens in Cotton Plants Coming from Seed Treatments

Abstract

Induced mutation techniques have been effectively used to obtain new variability in crop plants. Mutations are the primary source of genetic variability and therefore, some control over their frequency can be considered a valuable tool for plant breeding. Mutagens can be grouped into two broad categories according to their nature: physical and chemical. Doses must be optimized to increase the chances of generating mutants and achieve a population of mutagenized plants that allows a successful selection of mutants of interest. The aim of this study was to determinate the suitable doses of different mutagenic agents on Guazuncho 3 variety cottonseeds. Four doses of each treatment were evaluated and different phenotypic traits were recorded. The greatest effects on germination percentage, germination velocity index, plant survival and somatic effects were observed in treatments with EMS as the doses increased. Lower but significant effects were recorded in SA treatments. In contrast, there were no significant differences for these traits in X-rays and combined treatments, regarding the evaluated doses. The effects on growth rate were significant in chemical treatments with R 2 = 0.84 for SA and R 2 = 0.97 for EMS. In addition, it was observed that the EMS and X-rays treatments caused a greater number of off-type plants and chlorotic irregular-shape spots. The results of this study allowed to determine the optimal doses for the mutagens assayed on Guazuncho 3 cottonseeds, which will be used for generate M 1 population and show the importance of choosing an adequate dose for any mutation breeding program.Induced mutation techniques have been effectively used to obtain new variability in crop plants. Mutations are the primary source of genetic variability and therefore, some control over their frequency can be considered a valuable tool for plant breeding. Mutagens can be grouped into two broad categories according to their nature: physical and chemical. Doses must be optimized to increase the chances of generating mutants and achieve a population of mutagenized plants that allow a successful selection of mutants of interest. The aim of this study was to determine the suitable doses of different mutagenic agents on Guazuncho 3 variety cottonseeds. Four doses of each treatment were evaluated and different phenotypic traits were recorded. The greatest effects on germination percentage, germination velocity index, plant survival and somatic effects were observed in treatments with EMS as the doses increased. Lower but significant effects were recorded in SA treatments and no significant differences were observed for X‑rays and combined treatments. The effects on growth rate were significant in chemical treatments with R2 = 0.84 for SA and R2 = 0.97 for EMS. In addition, it was observed that the EMS and X-rays treatments caused a greater number of off-type plants and chlorotic irregular-shape spots. The results of this study determined the optimal doses for the mutagens assayed on Guazuncho 3 cottonseeds, which were used to generate an M1 population and show the importance of choosing an adequate dose for any mutation breeding program.