Physiological and biochemical evaluation of sixth generation of rice (Oryza sativa L.) mutant lines under salinity stress

In order to physiological and biochemical evaluation of seventh generation of rice mutant tolerant lines under salinity stress, an experiment was carried out as split plot arranged in a Completely Randomized Design with four replications. Main factor of experiment includes three levels of salt stress (0, 45, 75 mmol/l) and sub factor include 5 local rice mutant lines contain Tarom Hashemi 1, Tarom Hashemi 2, Tarom Hashemi 3, Tarom Chaloosi and promising Nemat. The results of analysis of variance of interaction salt stress and rice mutant lines showed that affect of interaction on studied traits was significant . In comparision with other lines and under all levels of salt stress, the results of experiment showed that Nemat had the highest content of Proline that was accompanied with increase protein. Catalase and Gayacol peroxidase activity under stress condition increased and and there was fewer amount of Malondialdehyde and ionic leakage. Considering the positive and significant correlation between dry weight of rice lines with Proline content (r = 0.36), Catalase (r = 0. 49), and Guaiacol peroxidase (r = 0.51) and negative correlation with Protein content (r = -0.29) and Malondialdehyde (r = -0.36) seems to suggest that the Nemat mutant can be as the most tolerant line, since the resistance mechanism of this line involves osmotic regulation and increasing the amount of proline amino acids through protein degradation and catalase enzymatic system, so these traits can be considered as basic mechanisms for tolerance to salinity.