Tradescantia pallida var. purpurea cuttings with flower buds are utilized in bioassays to diagnose genotoxic effects of water. The literature describes different substances used to adapt and recover the cuttings before and after exposure to water samples and also describes the effects of different exposure times. This study evaluated and compared the micronuclei (MCN) frequencies in T. pallida when cuttings with flower buds were submitted to different methodological conditions. The bioassay was then applied bimonthly during seven months to assess the genotoxic potential of a site located on the Sinos River in Campo Bom, Rio Grande do Sul, Brazil. Micronuclei frequencies in buds of cuttings adapted and recovered in distilled water and in Hoagland solution were 3.0 and 2.9, respectively, for cuttings exposed to river water, and 1.19 and 1.23 in controls. No significant differences among MCN frequencies were observed when cuttings were exposed for 8, 24 or 32 hours to river water (from 3.07 to 4.73) and in controls (from 1.13 to 2.00) in all samplings during a year. Adaptation and recovery of cuttings in distilled water or Hoagland solution and exposure for different times did not influence the response of T. pallida, indicating that all the conditions tested are viable for biomonitoring of water genotoxicity. Water samples from the Sinos River presented genotoxicity during the period monitored, evidenced by the MCN frequencies recorded which were significantly higher than the frequencies of the controls.
water bodies; genotoxic risk; micronuclei