Assessing salinity tolerance of bread wheat varieties using tolerance indices based on K+/Na+ ratio of flag leaf

In arid and semi-arid regions of the world including Iran, soil salinity is one of the major abiotic stresses. One of the ways to achieve high performance in these areas is using salt tolerant varieties. To assess salt tolerance indices, 41 bread wheat varieties planted in randomized complete block design with three replications under normal and saline irrigation conditions (0.631 and 11.8 dS/m, respectively) in Agriculture and Natural Resources Research Center, Kerman, Iran, in 2012. The results of analysis of variance showed significant effect of salinity on grain yield, sodium content, potassium content and Kﳖ ratio in flag leaf of the studied genotypes. Evaluating the correlation coefficients among recorded data indicated that there were the significant correlations between Kﳖ ratio under both condition and the indices of mean productivity (MP), geometric mean productivity (GMP), harmonic mean (HM) and stress tolerance index (STI) calculated based on this ratio. Therefore, MP, GMP, HM and STI indices were the best indices for selecting tolerant genotypes. Based on these indices, the genotypes Tabasi, Arg, Akbari, Bam, Sorkhtokhm, Bolani, Sistan, Karchia and Roshan were selected as salinity tolerant genotypes. These genotypes had also high Kﳖ ratio under both normal and saline condition. Also, the significant correlation between these indices and grain yield under stress condition showed that these indices will be useful to screen a huge set of genotypes and/or to select tolerant genotypes before determining the grain yield and is recommended as the suitable criteria for selecting the salinity tolerant and high grain yield genotypes.