Determination of QTLs Associated with Agronomic and Physiological Traits under Normal and Salinity Conditions in Barley

mapping the QTLs of agronomic and physiological traits, 149 double haploid (DH) lines from a cross between an Australian cultivar, Clipper (salt susceptible), and an Algerian landrace, Sahara3771 (salt tolerant), were evaluated under natural saline (Yazd Station, ECsoil=10-12.8 ds/m and ECwater= 9-10 ds/m) and normal (Karaj Station, ECsoil and ECwater ~2-2.5 ds/m) environments. There were remarkable differences between parents and among the lines for studied traits, including days to heading, relative water content, chlorophyll content, plant height, spike length, days to maturity, biomass, grain yield, harvest index, grain number per spike, 1000 grain weight, Na+ and K+ contents and K+/Na+ ratio. QTL analysis was performed using the genetic linkage map consisted of 517 molecular markers distributed evenly on all seven barley chromosomes spanning 1502 cM of barley genome based on composite interval mapping method. A total of 72 QTLs for the measured traits were determined, from which 40 QTLs were under normal and 32 QTLs were under salinity stress conditions. The phenotypic variation explained by individual QTLs ranged from 2.7 to 61.8%. A major QTL related to biomass, grain number per spike, grain yield, plant height and 1000 grain weight was identified on chromosome 2H in the vicinity of Vrs1 marker locus. In addition, for plant height, biomass, grain number per spike and 1000 grain weight, some stable QTL(s) under both salinity and normal conditions were identified on that locus which considered as salinity related QTLs. These QTLs can be useful in breeding programs for improving salt tolerance using marker-assisted selection.