Effect of gamma irradiation on seed germination and plant growth parameters of three rice varieties cultivated in Sri Lanka

Abstract

Development of rice varieties using induced mutation has seldom been applied in Sri Lanka. This study was carried out to determine the effect of gamma irradiation doses on seed germination and different plant growth parameters of three rice varieties in Sri Lanka. Two hundred grams of seeds of three rice varieties (Bg 94–1, Bg 1165–6, Suwandal) were irradiated varying doses of 200, 300 and 400 Gy using 60Co Gamma Cell Irradiator facility at the International Atomic Energy Agency (IAEA) laboratories Seibersdorf, Austria. The experiment was designed as split plot with three replications and conducted at the plant house of Rice Research and Development Institute, Batalagoda. The effects of gamma irradiation on seed germination and different plant growth parameters were evaluated (radio sensitivity testing). With the increase in gamma doses, seed germination, seedling emergence, seedling height, root length, and plant survival in the field were declined. Significant (P<0.05) differences were observed between different varieties in seedling height, root length and percentage of field survival. Gamma irradiation showed significant (P<0.05) negative correlation with seed germination (–0.52), seedling emergence (–0.54), seedling height (–0.54), root length (–0.50) and field survival (–0.42). Percentage of survival in the field was the least affected while the percentage reduction was 8.56. The most efficient and optimum dose to induce rice mutation of the varieties under investigation is within the range of 200 – 300 Gy. More pronounced adverse effect was observed for all the growth characters at the highest dose in all three varieties. Increasing doses above 400 Gy caused severe morphological damages to the rice plants and increased doses of gamma irradiation have a negative correlation with germination and other parameters of plant growth. A comprehensive study should be carried out to determine the optimum doses for different rice varieties that could be useful in rice varietal improvement programmes in Sri Lanka.