The breeding of barley (Hordeum vulgare) varieties, which combine high yield and drought tolerance, is a major challenge to the breeders in Mediterranean countries as drought is an important abiotic factor limiting yield. Identification of quantitative trait loci (QTL) influencing the response of yield and its components to drought stress will enhance our understanding of the genetics of drought tolerance and the development of more tolerant barley cultivars. Quantitative trait loci (QTL) for grain yield and its components were identified using 158 recombinant inbred lines (RILs) derived from a cross between the cultivars Tadmor (drought tolerant) and Er/Apm (drought susceptible) grown at Ghwair agricultural research station, and a linkage map including 87 AFLP markers assigned to 14 linkage groups was constructed with a genome distance coverage of 1321.7cM. Single-marker analysis, and interval marker analysis, including interval mapping (IM) and composite interval mapping (CIM), was used.
Thirty-eight QTL were identified for the measured characters, using a significant threshold of 2.5 LOD, in both IM and CIM. The phenotypic variation explained by individual QTL ranged from 2% to 82.1 %. In total, 32 and 47 different QTL were detected by IM and CIM respectively. Several major QTL were shown to linked two or more traits, this was evidence at linkage group 1 in case of grain yield and tiller number affected by one QTL, spike width, harvest index and biological yield where affected by one QTL, awn length, spike width and harvest index also govern by one QTL, fertile tiller number and harvest index showed one QTL in common, at linkage group 2 days to heading, harvest index and peduncle length was affected by four QTL, finally at linkage group 3 node number and leaf width showed one QTL in common.