Yashveer, ShikhaVerma, Swati2023-01-072023-01-072021-07https://krishikosh.egranth.ac.in/handle/1/5810191445Barley (Hordeum vulgare L.), is one of the major cereal crops and has been cultivated since ancient times in different parts of the world. In particular, heat stress at the post-heading stage causes considerable yield reduction due to the stress. Understanding the genetic variation, changes in physiological processes, and level of genetic diversity existing among genotypes are needed to produce new cultivars not only having a high tolerance to heat stress, but also displaying high yield. So to address this challenge, a panel of 316 diverse barley genotypes (AM2017) were procured. It was evaluated under two conditions timely-sown (TS) and late-sown (LS) conditions in two seasons of 2017-18 and 2018-19 at CCSHAU, Hisar. Ten agro-morphological, four physiological, and five grain malting quality traits were studied. Genetic diversity and population structure were explored in the AM2017 panel after genotyping it with the 50 K iSelect Illumina Barley SNP array. A set of 36,793 SNP markers, covering a genetic distance of 991.82 cM with an average marker density of 37.09 SNPs/cM, was obtained after quality filtration. The gene diversity (GD) and Polymorphic Information Content (PIC) at the genome level were 0.362 and 0.289, respectively. The phenotypic results showed a clear reduction in trait performance under the LS condition. Marker-trait associations (MTAs) were estimated using the compressed mixed linear model. Based on the estimated MTAs and linkage disequilibrium (LD) decay observed in the genome, putative QTL was identified as associated with the traits studied. The most robust QTL observed under both sowing conditions were further studied and validated using the previously reported QTL. Several traits were found to have QTL that was not found to be reported. The combination of analyses using SNPs and changes in physiological traits provided useful information on genomic regions taking part in heat stress tolerance.EnglishThesis