| Summary: | Barley (Hordeum vulgare L.) is the fourth most grown cereal crop in the world and can be successfully grown in a broad range of environments. Success of cultivation in subarctic regions such as Iceland depends largely on the ability of breeders to create high yielding cultivars that are adapted to the low temperatures, short growing season and strong winds that are often prevalent in these regions. An increased understanding of the genetic factors underlying traits such as earliness of flowering, maturation and height is therefore valuable. In this study, a Golf x Tampar barley mapping population consisting of 66 double haploid (DH) and 112 single seed descent (SSD) lines was phenotyped for three years in the field, and genotyped using the iSelect 9K barley SNP chip. The main aims were to characterize the population and to detect quantitative trait loci (QTL) for growth and development traits. Thereto, phenotypic data were analysed, population structure was assessed and linkage disequilibrium (LD) decay was calculated. Both genome wide association studies (GWAS) and QTL analysis were performed to link genotypic variation to the observed phenotypic variation. Results showed large phenotypic variance in earliness of heading, maturity and height in the population. Year, line type, row type and line ID all significantly influenced phenotypic variation. Between-year correlation of traits was very strong for heading and moderately strong for maturity. Within-year correlation between traits was highest for heading-maturity. Analysis of population structure suggested the presence of two subgroups, containing DH and SSD lines respectively, as well as a slight partitioning based on row type, while LD decay analysis showed that LD decay was slower in DH lines than in SSD lines and varied considerably for each chromosome. Heading was predominantly affected by one major QTL in the centromeric region of chromosome 2H, for which HvCEN was the most likely candidate gene. Candidate genes for other, smaller, QTL for heading ...
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