Variation of mutation frequency in Tradescantia stamen hairs cultivated near to a power reactor site

Tradescantia (clone KU-7) were grown at three points near a site of nuclear power plants and somatic mutation frequencies in Tradescantia stamen hairs were investigated for three years. The two points are located in the prevailing down-wind sector of the site. Mutational events in stamen hair cells were scored every day from the end of April to October for three years. In parallel with this observation, factors which have been thought to affect mutation induction, such as temperature, humidity, insolation, pollutants, radioactivity in the buds were measured at the three points. The daily exposure and radioactive concentration at three points due to the amount of the radioactive nuclide released from the nuclear power plant were calculated. Mutation frequencies fluctuated daily, but they were estimated rather constant on average at three sites. Increase of radioactivities in the buds or other plant tissues was not detected during this experiment. The daily exposure and radioactive concentration were very low, for example, the ratio of the maximum daily exposure to the doubling dose was less than 1 x 10-7. It has been definitely shown by this field experiment that radionuclide released from the nuclear power plants can not induce significant mutation of Tradescantia. It was concluded that Tradescantia stamen hair system was not appropriate to monitor the environmental radiation from the power reactor. (author)