Evaluation some of rice mutant lines (Oryza sativa L.) under salt stress through agronomic, physiological and enzymatic traits

Since, salinity stress threatens food security and sustainable agriculture production, the response of plants to salinity stress has always been one of the most important subjects of physiological and biochemical studies. In order to evaluate the mutant lines in terms of agronomic, physiological and enzymatic traits under salt stress, a factorial experiment was carried out based of a randomized complete block design in three replications using paddy soil and adjusting its salinity in pots. The treatments included four mutant lines (MLST1, MLTH1, MLTH2 and MLTH3) along with two tolerant controls (Deilamani and Nonabukra) and two sensitive controls (IR29 and Sepidrood) at three salinity levels (zero, 4 and 8 dS/m). Results indicated that the highest amount of proline was obtained at a salinity level of 4 dS/m in the MLTH2 mutant, which showed an increase of more than 1.3 times compared to the conditions of no salinity stress. Obtained. The highest and lowest amounts of malondialdehyde (MDA) were respectively at the salinity level of 4 dS/m and no salinity stress related to the MLTH3 genotype. According to the results, the highest level of superoxide dismutase (SOD) enzyme activity was related to the MLTH2 mutant at 4 dS/m salinity and the lowest was related to the MLST1 mutant at 8 dS/m salinity. In the absence of salinity stress, the highest paddy yield was recorded in the salt sensitive cultivar of Sepidroud. By comparison, after applying salinity stress, the lowest yield reduction was obtained in the MLTH2 mutant. In general, based on the biochemical and yield evaluation, the MLTH2 genotype was identified as the best salt tolerant line, which will be to recommend for further research