Abstract

Water scarcity restricts oat production. Developing varieties that sustain yield and industrial quality under these conditions can improve crop resilience to climate change. The aim of this study was to find oat accessions with superior agronomic performance under reproductive-stage water-deficit and beneficial QTLs. A group of 150 diverse oat accessions were evaluated in two environments at INIA Carillanca, Chile (38°41′ S, 72°24′ W, 188 m.a.s.l), which differed solely in water availability. One environment was rainfed (water-deficit) while the other received 50% supplemental irrigation over natural rainfall (well-watered) during grain filling. Trials were sown late to induce water-deficit. The accessions were sown in plots of 0.4 m2, using a randomized spatial design with three replicates. REML models were fitted to obtain Best Linear Unbiased Predictors (BLUPs). Then, a multi-trait-BLUP-selection index was used to find the accessions with the best agronomic performance. A set of 5891 filtered SNPs with 1800 BLUPs were used to conduct single and multi-trait GWAS. Fifteen accessions with superior agronomic performance, were chosen for their genetic gains in yield (41.7 and 61.1 g/m2), hectolitre weight (2.15 and 2.2 kg/hL), thousand grain weight (2.27 and 3.7 g), and panicle exertion (2.54 and 1.45 cm), under water-deficit and well-watered conditions, respectively. Five SNPs were associated to single agronomic traits, each negatively affecting grain quality and yield for breeding (result not shown). A beneficial QTL (7C.25585846, A/T) was found in the multi-trait GWAS exclusively under the water-deficit condition (LOD=5.32, QTL P < 0.0001). The QTL was associated to higher yield (29.7 ± 8.9 g/m²), increased thousand grain weight (0.85 ± 0.41 g), greater hectolitre weight (0.23 ± 0.25 kg/hL), and decreased plant height (-4.89 ± -1.18 cm). Forty-four accessions were identified as carrying the TT-allele. Eight accessions showing superior agronomic performance and carrying the favourable allele were selected for both research and breeding initiatives. A second season of field trials will be conducted to confirm results.