INDUCED VARIABILITY IN MORPHOLOGICAL, YIELD, CHEMICAL AND ANATOMICAL FEATURES OF TWO SESAME CULTIVARS BY USING GAMMA IRRADIATION

        The present work was conducted to study the effect of different doses of gamma irradiation (0 ,3 ,8 ,12 ,16 and 20 kr) on vegetative and yield component attributes of two sesame cultivars; Giza 32 and Giza 24 in M₁, M₂ and M₃ generations. The data revealed the following results (relative to the control) 1-The all doses had significant inhibited on the different attributed in M₁, whereas, the low dose 3 kr had an stimulatory effect in M₂ and the other doses caused inhibited the mean of different traits. 2- Various numbers of macromutants ( chlorophyll and morphological) were isolated in M₂ generation of two sesame cultivars, Giza 32 and Giza 24 with different doses. Five different types of chlorophyll mutations in each sesame cultivar; albina, xantha , chlorina, varigate and striate were detected. 3- The morphological mutations recorded in M₂ generation were; sterile, giant, dwarf, heavy branching/ high yield , early flowering, giant/ high yield, dwarf/ early, late/ high yield, long capsule and late flowering. Macromutants frequency differed according to the mutation type and the used dose. 4- Ranges of distribution in progenies of seeds treated with doses from 8 to 20 kr were mostly narrower and did not reach the maximum of the control limits. Meanwhile, at low gamma ray doses ; 3 kr the range were wider in plus and minus directions. 5- In the two cultivars, coefficient of variation values increased in most studied traits as a result of gamma ray treatments. 6- Correlation coefficients between seed yield/plant were positively and highly significant correlated with all studied characters. 7- Path coefficient analysis showed that number of capsule/ plant had the greatest effect upon seed yield followed by 1000 seed weight, while number of branches/ plant was the lowest in this respect. 8- In M₃ , the anatomical studies proved that the morphological differences of certain mutants are associated with differences in their internal make–up. 9- Chemical determination of dry seeds revealed that the percentages of oil excelled the control for the respect in 11 mutant families within the two cultivars.