Abstract

Climate change exacerbates water shortages during reproductive stage of oats, reducing yield and grain quality. This highlights the need for adapted varieties. The study evaluated the impact of water scarcity on critical oat traits to identify genotypes with enhanced resilience. The experiments were conducted at INIA-Carillanca, Chile (38°41′ S, 72°24′ W,188 m.a.s.l.). A selected group of 150 diverse Avena sativa accessions were grown in 0.4 m² plots with three replicates, using a randomized design with spatial correction. The accessions were evaluated in two environments differing only in water availability: one with water deficit condition (rainfed) and the other well-watered (irrigated at 50% of total available water). Water deficit was induced by late sowing under natural rainfall, while the well-watered condition involved irrigation until the end of grain filling. Key agronomic traits and the stress tolerance index (STI) were measured in all accessions. GGE biplot and REML-mixed models were used to estimate heritability, Best Linear Unbiased Predictions (BLUPs) and genotype by environment interaction to identify stable, contrasting genotypes. Genotype had a significant effect on grain yield, hectolitre weight, thousand grain weight, and number of panicles per plant (P < 0.0001) indicating genetic variability. Also, both the environment and the genotype-by-environment interaction were significant (P < 0.0001), showing different responses to water availability. Yield broad-sense heritability was 0.57 indicating sufficient reproducibility of the experiments. Oat accessions under water deficit showed decreased values for yield and thousand grain weight (9%), and for number of panicles per plant (50%) compared to the well-watered condition. Two oat accessions, representing advanced lines AVE054 (STI=1.92, BLUP=672 g/m²) and AVE003 (STI=0.52, BLUP=371 g/m²), were identified as having contrasting responses. On average, under water deficit, AVE054 produced 55% higher grain yield and 31% greater thousand grain weight than AVE003. Also, the selected lines showed higher yield stability, in comparison with the other oat accessions. The experiments will be repeated by a second season to validate field results, and a current greenhouse experiment is testing selected genotypes to identify water stress-responsive QTLs and genes, to improve oat resilience against climate change.