Abstract
The results of diallel analysis of radiosensitivity in six rice varieties were presented. The criterion of radiosensitivity used was reduction in root length following an exposure of the seeds to gamma-rays. It was found that: (1) The temperature under which the seeds ripened had a strong influence not only on mean radiosensitivity but also on the genetical behavior of radiosensitivity in the subsequent generation. (2) After a 20°C treatment, radiosensitivity was determined by a genetic system of additive effect and incomplete dominance. No evidence for nonallelic interaction was obtained. (3) After a 30°C treatment, however, a non-allelic interaction was observed, which was due to two particular partental lines; their removal recovered additivity between loci of the remaining parents. (4) After the 20°C treatment, dominance was in the direction of both increasing and decreasing sensitivity, while dominance after 30°C treatment was in the direction of increasing. (5) The proportion of dominant alleles to all parental alleles also differed according to the temperature treatment. (6) No correlation was found between the radiosensitivity shown by log 100K and the root length of the control.
