Investigation of gamma ray effects on pollen germination and parthenogenic haploid embryogenesis in Rosa damascena Mill.

Haploid and doubled haploid (DH) plants are able to accelerate plant breeding programs. This study was conducted on gamma ray irradiated pollen grains of damask rose crosses and induced parthenogenic haploid embryos. Two genotypes of G32 and G40 of damask rose as maternal plant and G22 and mixed of forty collected genotypes from all over the country were used as paternal plants. After determining of suitable collecting time, paternal blooms were irradiated by gamma ray from 60 cobalt in five levels 0, 250, 500, 800 and 1400 Gy. Emasculated maternal flowers were pollinated by the irradiated pollens. Fruits were collected 16 and 19 days after pollination. In order to determination a suitable culture medium the immature embryos were extracted and cultured in three combination of MS medium. To overcome the existing dormancy, half part of embryos was kept at 1-4 degree centigrade for 2 month. Fruit formation percentage and seed averages per fruit depended on ray intensity, maternal and paternal parents. Half MS + vit in was better than the other medium. Chilling was necessary for overcoming the embryo dormancy. On the basis of morphological studies, especially number of chloroplasts in guard cells, the most haploid embryos were obtained by 250 Gy.