| Radiosensitivity in pollen grains of Triticum
and Aegilops T. MABUCHI and S. MATSUMURA National Institute of Genetics, Misima, Japan Relation between radio-sensitivity and ploidy or genome constitution was investigated in several species of Triticum and Aegilops. Anthers before dehiscence were irradiated by X-rays (173 kVp, 25 mA, 1 mm Al filter) at 1, 2 and 3 kr with dose rate of 200 r/min. Pollen grains were dusted on the emasculated florets of the same species. Seed set, mean grain weight and germination were recorded. Seed setting was noticeably impaired even at 1 kr and reduced to 24-75% and 3.1-25% of control at 2 and 3 kr, respectively. Germination rate also decreased to 35-88% of control at 1 kr and was markedly affected (3.3-22.5%) at 2 kr. Percentage of viable seedlings (per cent success of crossing) was calculated from seed setting x germination rate. It was for diploid Triticum and Aegilops species about 25% of control at 1 kr, and for several species of tetra- and hexaploids it was ranging from 30 to 55%. It is, therefore, concluded that diploid species are most sensitive to radiation, T. monococcum as well as Ae. squarrosa, but there is no clear difference between tetra- and hexaploid Triticum species. |