| چکیده انگلیسی مقاله |
Extended Abstract
Introduction and Objective: Salinity stress is one of the most important limitations of rice cultivation worldwide. On the other hand, the use of physical and chemical mutagens can be very important not only to the development and combination of new genes or alleles with agricultural importance but also to introduce genotypes more adaptable and stable to adverse weather and soil conditions. For this reason, with the development and progress of rice varieties that are tolerant and adapted to salinity, it is possible to increase the sustainable production of this stable food. Therefore, the present study was conducted with the aim of investigating the response of the tenth generation (M10) of rice mutants to salinity stress in the reproductive stage using agronomic and biochemical characteristics.
Material and Methods: In this research, 13 mutant lines of Seng-e-Tarem, Hashemi and Khazar cultivars using gamma ray irradiation from Cobalt 60 which have been previously identified as tolerant lines in molecular studies were used along with the tolerant cultivars of Nonabukra and Deylamani and sensitive cultivars of IR29 and Sepidrood. The genotypes were exposed to three levels of salinity (0, 4 and 8 dS/m) from the source of sodium chloride. A factorial experiment based a randomized complete block design (RCBD) and a factorial split based a RCBD with three replicates were used to evaluate agronomic traits along with yield and biochemical traits, respectively. The measured parameters were tillers number (TN), the number of filled (NFG) and unfilled grains (NUG), 1000 grains weight (TGW), plant height (PH), Days to 50% of flowering (DTF) and the paddy yield (PY), and for the biochemical traits, the activity of catalase (CAT) and superoxide dismutase (SOD), protein (PN), proline (PR) and malondialdehyde (MDA) contents and electrolyte leakage (EL) percentage.
Results: The results of the variance analysis showed that the effect of salinity and genotype and their interactions were significant for all the measured traits. A wide range of genetic diversity was observed among the genotypes for the agronomic and biochemical traits. Among the traits, PY was identified as the best and the most indicative trait to classify the tolerant genotype under salt stress conditions. Among the investigated mutants at different levels of salinity, the highest PY was recorded in MP6, MP10 and Deylamani genotypes, respectively. PY value in MP10 mutant at the salinity level of 8 dS/m was closed to Deylamani variety (tolerant check). With the increase of salinity from zero to 8 dS/m, the measured traits adversely affected. The cluster analysis diagram of studied genotypes based on agronomic traits and PY at a salinity level of 4 dS/m classified the genotypes into three separate groups. The genotypes MP2, MP3, MP4, MP9, and MP10 were grouped in the second group, in which Deylamani cultivar was also present as a tolerant check. The cluster analysis diagram of agronomic traits and PY at the salinity stress level of 8 dS/m divided the genotypes into four different groups. In the third group, two genotypes of MP9 and MP10 were included with Tarem Deylamani variety (tolerant check). The correlation coefficient between agronomic traits in 8 dS/m of salt conditions showed that PY had a positive and significant correlation with PH (r=0.51), the NFG (r=0.88) and TGW (r=0.63). Also, there is a negative correlation between DTF with PH (r=-0.70) and NFG (r=-0.62) and a positive and significant correlation with TN (r=0.60). Biplot analysis divided the studied lines into four groups based on agronomic traits at a salinity level of 4 dS/m. The first group includes six mutant lines as very sensitive group, the second group includes two mutant lines as sensitive group, the third group with three genotypes including lines MP9, MP10 and Tarem Deylamani variety (tolerant check) as tolerant group and the fourth group with six genotypes included lines MP11, MP12, MP13 and Nonabukra variety (international tolerant check) as well as Sepidrood and IR29 varieties as high salt tolerant group. Also, biplot analysis based on agronomic traits at a salinity level of 8 dS/m divided the studied lines into four groups. The first group consisted three mutant lines as very sensitive group, the second group included six lines as sensitive group, the third group involved five genotypes including MP11 and MP13 lines and Nonabukra varieties (tolerant check), Sepidrood and IR29 as the tolerant group and the fourth group with three genotypes included MP9 and MP10 lines and Tarem Deylamani variety (native tolerant check) as high salt tolerant group. For biochemical traits at 8 dS/m of salt stress, the highest amount of SOD was recorded in Deylamani cultivar (tolerant check), PN for MP2 mutant, PR for MP3 mutant, and the lowest amount of EL and MDA was recorded for MP2 and MP10 mutants, respectively.
Conclusion: In general, PY of MP10 mutant line in salt stress conditions was closed to Deylamani as a native salt tolerant cultivar, therefore could be introduced as a superior line for further research in saline conditions. |