Production of Haploids in Cucurbita pepo L. through Parthenogenesis Induced by Gamma-Irradiated Pollen

Production of haploid plants was studied in summer squash via induction of parthenogenic embryos. Female flowers were pollinated with anthers irradiated by different doses of gamma ray (25، 50، 75، 100 and 200 Gray) and induced embryos were rescued and cultured in specific medium. The results achieved showed that the highest number of embryos was obtained in 50 and 75 Gray doses (82%)، however، no embryo was produced at 200 Gray. Gamma ray doses and embryo stage had significant effect on frequency of embryo and plant regeneration. Highest embryo regeneration and haploid formation (27 plant regeneration and 11 haploids formation، respectively) were recorded at 50 Gray. All amorphous embryos produced only diploid plant، though 29. 17، 33. 33، 57. 14، 66. 67، 100 and 100 percent of plants derived from cotyledon، heart، torpedo، arrow-tip، torpedo-tip and globular embryos respectively، were haploid. Based on this study، out of the 7744 extracted seeds، 127 embryos and 44 plants were regenerated; among those 17 plants were identified as haploid plants using chloroplast counting، Flow-Cytometry technique and morphologic traits evaluations.