This study assessed the biochemical changes in wheat plants exposed to gamma radiation. Seeds of two wheat cultivars Roshan and Bam were irradiated with 100, 200, 300 and 400 Gy and were immediately planted into soil plots in greenhouse. Leaf samples for various measurements were taken from flag leaves on the 7th day after anthesis. The results demonstrated that seeds of cv. Roshan did not germinate above 200 Gy dose. Gamma irradiation increased the malondialdehyde content remarkably in both cultivars. In both cultivars the chlorophyll content increased at 100 Gy. However, the highest amount of proline was obtained at 200 Gy. Cultivars Roshan and Bam at 200 Gy showed the highest (70.98 µg/g Fw) and lowest (38.91 µg/g Fw) amount of total soluble protein, respectively. Increasing gamma doses improved the activity of peroxidase in both cultivars, but the effect was much greater in cv. Bam than that in cv. Roshan. It seems that cv. Roshan was more sensitive to irradiation stress than cv. Bam. Overall, leaf soluble protein, chlorophyll contents, and lipid peroxidation were found to be effective in assessing the response of wheat cultivars to gamma radiation.

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