Doctor of Philosophy (PhD)


School of Plant, Environmental and Soil Sciences

Document Type



Common oat (Avena sativa L.) is an allohexaploid (AACCDD, 2n = 6x = 42) crop grown primarily for human consumption and animal feed, and as a forage source worldwide. Southern oat breeding programs prioritize forage yield and regrowth, grain yield and quality, winter hardiness, and disease resistance. While spring oat breeding programs target grain yield and quality (beta-glucan content), winter oat breeding programs target forage yield and quality in addition to grain yield. Recent advances in genotyping by sequencing (GBS) and single nucleotide polymorphism (SNP) array have facilitated identification of quantitative trait loci (QTLs) and SNPs controlling various traits through biparental QTL mapping and genome-wide association studies (GWAS). The present study was undertaken to understand the genetic variation for agronomic, forage and milling quality traits within a southern oat association panel (SOAP) of 288 accessions and to identify trait-associated SNPs and linked genes. Growth habit had significantly high correlation with relative maturity and freeze tolerance. For forage traits, invitro digestible dry matter was positively correlated with relative feed value, but negatively correlated with acid detergent fiber and neutral detergent fiber. For milling traits, groat% was positively correlated with test weight. The broad-sense heritability of the agronomic traits was low to high (6.0-89.7%), low to intermediate (19-41%) for forage traits, but low (20-33%) for the milling traits. The SOAP accessions formed three clusters (LA/FL, TX, and NC/SC) with NC/SC alleles shared between clusters. GWAS identified trait-associated SNPs explaining up to 25.0% of the phenotypic variance. Markers GMI_ES14_c5137_154 and GMI_ES22_c15631_526, GMI_ES03_c15797_251, GMI_ES_LB_9068, and GMI_ES15_c12600_230 common between multiple forage traits were considered important. Similarly, the marker GMI_ES02_c4792_372 was considered an important candidate for agronomic traits such as relative maturity, freeze tolerance, winter stress and tip burn. Of special significance was the marker GMI_ES02_c8186_443 that had highly significant associations with multiple forage quality and agronomic traits. Genes such as lipid transfer protein, proteases, etc. linked to the significant SNPs are known to be associated with ADF, NDF and IVTDMD. The candidate markers need to be validated for utilization in marker-assisted breeding for improvement of traits of interest in southern US oat variety development programs and elsewhere.



Committee Chair

Harrison, Stephen A.

Available for download on Sunday, November 01, 2026