Effect of gamma ray treatment on seed germination traits and seedling growth of Agropyron elongatum and Bromus tomentellus

In this study seeds of two important rangeland species were treated with 3, 6, 15, 20, 30, 50, 100 and 150 Gy of gamma ray and its effect on germination traits was investigatedin range management laboratory of Natural Resources Faculty of Tarbiat Modares University. This investigation was performed in Bahman (January, 2011), and irradiated seeds were sown in Petri in a completely randomized experimental design for each species with 3 replications of 50seeds dishes, and then germination traits were evaluated. The results showed that gamma ray had no significant effect on germination traits of B.tomentellus. About the seeds of A.elongatum, the dose of 6 Gy had the most positive effect on the parameter of germination speed that had significant difference with non-irradiated seeds (p<0.05), and this parameter increased from 5.77 to 7.89 (seeds/day). Also, the vigority index of this grass was higher in 30Gy treatment and increased from 89.83 in non-irradiated seeds to 118.11 in treated seeds. Likewise, the wet weight of seedling’s root and shoot was higher in these treat too; however, the highest number of seedling’s root dry weight was related to 20 gray treat, and there was no significant difference in seedling’s shoot wet weight. In general, 100 and 150 Gy of gamma ray had negative effect on germination traits.This results show that the effect of gamma ray varies on seeds of the two investigated species