Comparison of Yield, Na+ and K+ concentrations, and evaluation of stress indices in wheat cultivars and elite lines under salt stress

Introduction Salinity stress is a serious threat of plant growth and production over the world. Soil salinity is the major problem, which affects the yield of wheat crop. It is commonly observed in arid and semi-arid regions of the world (Atlassi et al., 2009). Crop growth reduction due to salinity is generally related to the osmotic potential of the root-zone soil solution. The relative salt tolerance of wheat crop is 7.0 dS∙m−1 and its yield decrease is 25% at 9.0 dS∙m−1 (Kramer and Amtmann, 2012). The reduction in growth and yield varies between cultivars (Sultana et al., 2000). The varietal differences in salinity tolerance that exist among crop plants can be utilized through screening programs by exploiting appropriate traits for salt tolerance. The recently developed cultivars form a much diversed genetic base and may therefore possess a wider range of salts stress tolerance. Materials and Methods In order to study the effects of salinity stress on grain yield, yield components, morphological traits and concentrations of Na+ and K+ of eight wheat cultivars and elite lines, two separate experiments in randomized complete block design with three replications were conducted at two places of Amirabad (saline condition) and Mohammadieh (none saline condition) in 2009-2010. Four elite lines including MS-88-8, MS-88-16, MS-88-17 and MS-87-8 and four salt tolerant cultivars including Ofogh, Arg, Bam and Kavir investigated. The first experiment conducted at the Research Farm of Birjand University located in Amirabad region which texturally the soil was sandy clay loam, with pH=8.2 and EC=13.69 ds.m-1. The second experiment conducted at the South Khorasan Agricultural and Natural Resources Research and Education Center located in Mohammadieh region which texturally the soil was loam, with pH=8 and EC=4.79 ds.m-1. Investigated traits were including flag leaf area, spike length, peduncle length, plant height, number of grain per spike, thousand grain weight, biological yield, grain yield, harvest index, Na+ and K+ concentrations and stress indices. Data analyses were performed using two-way analysis of variance with SAS 9.1. Means of treatments were compared according to Duncan test at the 5% level. Results and Discussion Results showed that salt stress led to significant reduction on all morphological traits and had the most effect on plant height. Salt stress had no effect on number of grain per spike, 1000 grain weight, and Na+ and K+ concentration in shoot. Biomass and grain yield in salt stress condition decreased 38.2 and 44.5 percent, respectively. MS-87-8 and Ofogh with grain yield of 4.02 and 3.72 ton/ha were better than Bam and Kavir checks and same as Arg. The best indices for selection of tolerant cultivars were HARM, STI and GMP, which Arg and MS-87-8 identified as the most tolerant based on them. Conclusion The results of this experiment showed that salinity significantly reduced grain yield, biomass and morphological traits of wheat cultivars and promising lines. Meanwhile, Arg cultivar and then MS-87-8 line had the highest grain yield and identified suitable for saline condition. Due to the presence of salinity resistance genes, they can be used for breeding of cultivars with high potential yield and also to cultivate in saline conditions.