Identifying QTLs associated with salinity tolerance in the early stages of germination of barley

Salinity is one of the main osmotic stresses that limit plants growth and development through changes in osmotic and ionic balances. In order to mapping of genomic regions of controlling quantitative trait locus (QTLs), related to salinity tolerance in grain barley and assessment of associated indices, an experiment was conducted during 2015 using 72 double haploid lines of barley along with their parents (Stepto and Morex) in randomized complete block design (RCBD) with two replications, at three conditions including normal and two salinity levels of NaCl (100 and 200 mM NaCl). Investigated traits in this study were coefficient of velocity of germination, final germination percentage, mean germination time, germination rate index and average germination speed. QTL analysis using composite interval mapping (CIM) was performed based on mean of three environments. Overall, for different traits 47 QTL with LOD≥2.5 was identified and 7 additive-by-additive significant epistatic effects were observed. Total phenotypic variance explained by the QTLs varied from 29.97 to 77.15 percent, which the lowest related to germination rate index under stress conditions of 200 mM and the highest related to coefficient of velocity of germination in normal conditions. The highest LOD (8.27) was obtained for coefficient of velocity of germination on chromosome of 4Hb under 100 mM stress conditions. Stable QTLs in three environments as well as linked markers could be used in the marker assisted selection (MAS) to improve germination characteristics under salinity conditions at different trials replicated over years.