Abstract

The effect of single treatment with gamma-rays, sodium azide and combination treatments of gamma-rays and sodium azide on seed germination, seedling survival, pollen fertility and seed set in sunflower (Helianthus annuus L.) M₂generation was studied in the varieties of USH-430 and SHSF-333. There was gradual decrease of seedling survival and pollen fertility with an increase in the dose of mutagen in both varieties. The percentage of lethality and achene sterility gradually increased with an increased dose. In USH-430 variety, the seed set percentage was significantly increased at 6kR, 4 mM and 6 kR + 6 mM, respectively. Mutagenic effectiveness decreased with an increased dose or concentration of gamma-rays and sodium azide in both varieties. In combined treatments, mutagenic effectiveness gradually increased with an increased dose. Mutagenic efficiency increased with an increased dose in case of gamma-irradiated seeds in both varieties. Mutagenic efficiency decreased gradually with an increased dose in both varieties. The linear correlation co-efficient was positive in case of gamma-rays and sodium azide separated, whereas in combined treatment, negative correlation was observed.

Key words: Sodium azide, gamma-rays, seed set, pollen sterility, mutation frequency, mutagenic effectiveness, mutagenic efficiency.