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Abstract
Two experiment were carried out on Helichrysum bracteatum L. plant at the experimental nursery of the ornamental hort. dept., Fac. agric., Cairo univ., Giza, Egypt, during the three successive seasons (2014/15, 2015/16 and 2016/17). The aim of this study was to investigate the effect of gamma irradiation and sodium azide on growth, flowering parameters and anatomical structure of leaves and flowers in three generations (M1, M2 and M3). In addition, PCR, RAPD-ISSR, cluster analyses were used for DNA polymorphism among obtained mutants. The obtained results showed the following: Seeds of H. bracteatum L. were exposed to eight doses of gamma radiation (5-40 Gy). The results showed that the highest germination percentage was obtained by 5 and 10 Gy, whereas 40 Gy gave the lowest germination percentage in the M1 and M2, respectively. Low doses (5 and 10 Gy) of gamma radiation increased the vegetative growth parameters per plant, while higher doses decreased them as compared with the control. Also, the low doses of gamma radiation increased No. of flowers and flowers diameter per plant in M1 and M2. Were obtained on many morphological variations in flowers color and leaves shape through three generations with doses 15, 20, 25, 30 and 35 Gy. Gamma rays induced changes at DNA level among the mutants studied. The UPGMA cluster analysis showed the genetic relationship among the gamma irradiated and control individuals felled into two main clusters