The aim of this work was to develop methods, based on the germination test, for identification of rice seeds tolerant to imazethapyr herbicide. The method that uses wet paper was developed in two stages. In the first stage the seeds of BRS 6 - Chui cultivar and THI lineage were submitted to germination on towel paper soaked in solutions with six different concentrations of the herbicide, containing 106 g/l of the imazethapyr herbicide active ingredient. The evaluations were carried out on day seven and fourteen. In the second stage, we used the concentration indicated in the previous experiment. Seeds of the THI lineage and BRS 7 - Taim, BRS Pelota, BRS Ligeirinho, BR-IRGA 410 and IRGA 417 cultivars were submitted to germination on paper towel soaked in a solution containing imazethapyr herbicide at 0.001% (v/v), diluted in water, and evaluations done on day seven. The method that uses immersion of the seeds was developed in two stages. In the first one, seeds of the BRS 6 - Chui cultivar and THI lineage were hydrated in solution with different concentrations of the imazethapyr herbicide, containing 106 g/l of the active ingredient, for four hours at 25ºC, and then submitted to germination on paper towel soaked in water, with evaluation on days four and seven. In the second stage, using the concentration indicated in the previous stage, seeds of the THI lineage and BRS 7 - Taim, BRS Pelota, BRS Ligeirinho, BR-IRGA 410 and IRGA 417 cultivars were hydrated for four hours at 25ºC in 0.5% solution (v/v), diluted in distilled water, and then submitted to the germination test with evaluation on day four after sowing. The concentration indicated for identification of rice seeds tolerant to imazethapyr herbicide is 0.5% (v/v) diluted in water, and evaluation done on day four.
Oryza sativa; mutation; bioassay; germination
