Abstract
Pollen grain fails to bud when irradiated prior to meiosis. On this account, it is considered that the meiosis is the epoch to radiation injury. In our experiment, it was decided that the sensitivity became lower when the time of irradiation was more distant and elevated again in mitosis. The time prior to meiosis is not the critical time. The sensitivity of pollen grain is high not noly in meiosis but also in nucleus division as other cells.
