Evaluation of Wheat Germplasm in Response to Salinity Stress

To improve bread wheat salt tolerance, new genetic sources of salt tolerance are indispensable, and this requires a screening of wheat germplasm. In order to evaluate bread wheat germplasm, 34 accessions including; hexaploid wheats (AABBDD), tetraploid (AABB) and wild relative diploids (DD and AA genome) collected from different regions of Iran were evaluated under normal vs. salinity stress (NaCl) conditions, using a factorial experiment in a hierarchical design with three replications. The assessed characters were biological dry weight, tissue Water Content (WC; shoot H2O per dry shoot mass), Na+ and stress tolerance index (ST). Stress tolerance was significantly correlated with tissue Na+ concentration and WC. The estimated coefficient of genetic variability (%CVg) via expected mean squares showed that there is a significant genetic diversity in population. Cluster analysis on the basis of Ward's method rendered all the accessions clustered into four clusters at a distance of 7.4. There was a good consistence between clustering results and %CVg. Some accessions were observed with a high shoot Na+ concentration and a high level of ST while some with low Na+ along with high ST. Therefore, breeding for improved ST in bread wheat needs a selection for traits related to both Na+ exclusion and tissue tolerance as well as pyramiding of both into breeder’s lines, using Marker-assisted selection that has the potential to accelerate this breeding process.