Callus induction and proliferation as affected by EMS and UV-B mutagens in rice (Oryza Sativa L.) genotypes

Seeds of the two rice genotypes namely Amber 33 (A33) and Amber Baghdad (AB) were divided into two groups; the first was presoaked in different concentrations of ethyl methane sulphonate (EMS) as chemical mutagen for different duration times (3, 6 and 12) hrs, and the other was exposed to different exposure times of ultra violate (UV-B) radiation (280-320 nm) as physical mutagen for different times (20, 40 and 60) min at room temperature. Treated and non-treated seeds were transferred into the callus induction medium containing 2.5 mg/L 2,4-dichlorophenoxy acetic acid (2,4-D) and 0.5 mg/L benzyl adenine (BA) under aseptic conditions. Calli were divided into two groups the first was treated with several EMS concentrations (0.0, 0.50. 1.0, 1.50 and 2.0) % for 30 min and the second group was irradiated with UV-B for several exposure times (20, 40 and 60) min to induce genetic variation. Seeds were treated with the optimum dose that caused high % in callus induction. The dose that caused 50% reduction in callus growth mass was adopted.