Abstract
Barley (Hordeum vulgare L.) ranks fourth in global cereal grain production and is an important crop for animal feed, malting, and human consumption. Identification of two-row barley germplasm with drought tolerance can increase genetic diversity and facilitate future barley breeding efforts. The present study evaluated 480 two-row spring barley accessions from the USDA National Small Grains Collection across two years of irrigated and terminal drought trials for grain yield, test weight, protein content, thousand-kernel weight, and kernel size. Twenty accessions were identified that showed stable high yield, high test weights, and low protein content across trials. An additional 10 accessions were identified with stable high yield, high test weights, and high protein across trials. Genome-wide association mapping with 6,366 single nucleotide polymorphism (SNP) markers revealed 15 drought-stable genetic loci significantly (false discovery rate-adjusted P < .05) associated with at least one agronomic trait across and within treatments. One locus, on chromosome 2H between 27.2 and 29.8 Mbp, was significantly associated with heading date, plant height, and kernel size across treatments in this study, and the PPD-H1 mutation in a previous study. Genetic loci on chromosomes 2H and 3H were significantly associated with increased test weight, and loci on chromosomes 3H and 5H were significantly associated with decreased grain protein content across treatments. Accessions and SNP markers significantly associated with agronomic trait stability across terminal drought and irrigated environments can assist with the development of drought-tolerant barley germplasm.