Effect of irradiation and polyethylene glycol on drought tolerance of MR269 genotype rice (Oryza sativa L.)

Background: A drought-tolerant genotype should be identified and improved for the continuity of food security because of the global importance of rice. Mutation and tissue culture techniques are effective and important for studies on the development of potential rice resources. The effects of irradiation and drought stress on rice genotype MR269 of Oryza sativa L., differing in drought tolerance capability were investigated. Methodology: The seeds of the genotypes were exposed to gamma rays at 350 Gy. Naked seeds were initiated onto half-strength standard MS medium enhanced with 0, 10 and 20% polyethylene glycol (PEG) 6000. The effects of PEG on root and shoot length, fresh and dry seedling weights, total chlorophyll and carbohydrate contents and proline accumulation were examined. Significant differences were observed in the studied traits. The non-irradiated seeds presented the highest mean shoot and seedling fresh weight, whereas the irradiated seeds presented the largest root length and highest proline concentrations. Results: The PEG produced a decrease in the means of all the characteristics investigated by enhancing PEG concentration, except for the means of proline content, which increased with the increase in PEG concentration. The irradiated genotypes produced the highest values of root length, dry weight, chlorophyll, proline and carbohydrates in concentrations of 20% PEG compared with the non-irradiated ones. Conclusion: Thus, a positive signal exists in the effect of radiation on these characteristics in drought tolerance. Research on the improvement of a drought-tolerant genotype under different drought conditions is necessary to enhance rice productivity and food security.