Effects of Irradiation Doses on Haploid Embryo and Plant Production in Naked and Shelled Seed Pumpkins

Abstract

This study was carried out for two objectives: 1) to test efficiency of "pollination by irradiated pollen technique" in naked seed pumpkins (Cucurbita pepo var. styriaca) on parthenogenetic embryo stimulation and plant production compared to shelled seed genotypes (Cucurbita pepo var. pepo); and 2) to find the most suitable doses of irradiation both for naked and shelled seed pumpkins. As plant material, a total of 15 genotypes (ten naked and five shelled) were used and 3 irradiation doses of gamma rays (50, 100 and 150 Gy) were compared. During the study, a total of 2073 embryos were rescued from different genotypes and 979 of these developed into plants. Haploid embryos were obtained in all of the tested genotypes and no significant differences have been observed among genotypes. Although all of the three irradiation doses produced embryos and plants, more haploid plants were obtained from 150 Gy. 75 of the developed plants were acclimatized and cultivated in a polyethylene greenhouse and in 29 of these, ploidy levels were determined using indirect methods (existence of pollen, leaf and flower features, stoma density, chloroplast numbers in guard cells) and flow cytometry. As the result of the observations, 43% of these plants were found to be haploid and 57% were diploid. Haploid plant percentages were 36.7, 60.0 and 100.0% for 50, 100 and 150 Gy, respectively.