Radiobiological Studies on Plants, IV.

Abstract

Ripe pollen grains of Lycopersicum pimpinellifolium were exposed to 230kVp X-rays, and 1.17 and 1.33Mev mixed gamma-rays from 60Co source, ranging from 10kr to 110kr at increments of 10kr. According to the authors' previous study pollen grains irradiated with these dosages of X-rays germinated very well in vitro.In the present investigation, 1, 207 and 203 flowers which were previously emasculated were pollinated with irradiated and non-irradiated pollen grains, respectively.The percentage of fruit-setting and the weight of fruits distinctly decreased when pollen grains were exposed to increasing doses of radiation. These fruits set few plump and viable seeds, but some small and empty seeds were obtained in numbers clearly inversely proportional to the amount of irradiation doses.Only six plump seeds were obtained in 537 fruits fertilized with irradiated pollen grains and five of them germinated. All of them had the normal number of chromosomes (2n=24) of L. pimpinellifolium. No difference on biological effects between X- and gamma-irradiation was recognized in the present experiment.