1966 Volume 35 Issue 1 Pages 80-88
Nowadays ionizing-radiation treatment is becoming one of the influential techniques in plant breeding programs. Since 1959 the author tried continuously to expose the dry seeds of various annual and biennial flower plants, including total 49 species (one hundred and more varieties and strains), to acute gamma rays from 60Co at the Japan Atomic Energy Research Institute, Tokai, intending to ascertain the reliable influence of radiation effect upon the plants growth and to obtain any useful mutants for breeding materials.
As the result, some noticeable biological phenomena were found out. Firstly, there appeared distinguishable interspecific differences of radiosensitivity among them. Many plants examined were classified conveniently into the following five groups, regard to their radiosensitivity for survival: much resistant (for examples, Malthiola incana, Cheiranthus cheiri), resistant (Brassica campeslris, Brassica oleracea), medium (Glycine Max, Cleome spinosa), susceptible (Porlulaca gradiflora, Lychnis coronaria), and much susceptible (Capsicum annum, Cosmos sulphureus). Secondly, some interesting and noteworthy variants were obtained in X1 generation or the successive descendants. The conspicuous examples are fasciation of main stems (Cosmos bipinnalus), defasciation of broadly flattened stalks (Celosia cristata), color change of petals(Moricandia sonchifolia), formation of polyfoliaged leaves (Trifolium repens), and duplication of petals (Cheiranthus cheiri). Although a part of these variants were sterile and went out soon, some of the remainder were viable and still now are segregating the peculiarly characterized seedlings in their progenies.
