Relative biological effectiveness of x-rays and 0.43-MeV monoenergetic neutrons on somatic mutations and loss of reproductive integrity in Tradescantia stamen hairs.

Young inflorescences of Tradescantia clone 02 were irradiated with 0.43-MeV neutrons at doses of 0.163, 0.54, 1.07, 2.16, 4.34, 7.97, 12.7, 17.2, and 24.4 rads. Data from this experiment were compared with data from 250-kVp x-rays with doses of 11.5, 24.0, 48.0, 96.0, 144.0, 192.0, 240.0, 288.0, and 432.0 rads. In both experiments, the stamen hairs were scored daily from day 7 through day 23 postirradiation. Relative biological effectiveness (RBE) values were determined for four cellular aberrations: the color change from blue to pink and to colorless, and the morphological change from normal-sized blue cells to either blue dwarf or blue giant cells. Maximum RBE values found were 23.5 for blue dwarf, 30.7 for pink, 39.1 for colorless, and 120.5 for blue giant cells. In all cases, the RBE decreased with increasing dose but only slightly so for blue dwarf cells. Survival curves were constructed with hairs of three different lengths (cell numbers) being considered as the surviving fraction. RBE values of abo...