The seeds of two hybrids FSS64 and SF0049 of sunflower (Helianthus annuus L.) were irradiated with different doses of gamma irradiation i.e., 10, 15, 20, 25 Krad from the source of cobalt Co60 at Nuclear institute for food and agriculture (NIFA), Peshawar. The irradiated seeds were sown in the research area of the department of Botany, Shaheed Benazir Bhutto University, Sheringal, Dir-Upper during the crop season of 2016. It was noted that a negative correlation was established in doses of 10, 15, 20, 25 Krad versus number of parameters like number of leaves, number of seeds per head and fresh seed weight. With the gradual increase in doses, decreases in mean values for the mentioned parameters were observed. Significant reductions in the mean values were observed for mentioned parameters in both the hybrids FSS64 and SF0049 of sunflower and consistently retardation was recorded with the increasing doses. Direct relationship occurred in the mean values of days taken to germination and maturity while on the other hand means values significantly raised with the rising of doses thus the duration of the mentioned parameters is increased. It was also concluded that rising of doses caused restraining in the mean values of all the parameters, which clarified that both hybrids were sensitive to high doses of gamma irradiation. Furthermore, there were also recovered a few Mutant genotypes in FSS64 hybrid at 15 Krad due to genetic variability with proliferation of two capitula with single peduncle on the main shoot. Differences in the mean square values through analysis of variance with respect to different doses of irradiation for all the parameters were highly significant, while due to the hybrids effect of the number of leaves was non-significant. Moreover, non-significant results were achieved in the mean square values due to the relations between hybrids and doses for days to maturity and the number of leaves
