Drought severity and duration effects oat yield and yield components

Authors: Neupane, Dhurba; Osborne, Shannon; Schneider, Sharon; Ewing, Patrick

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/13/2025
Publication Date: 11/22/2025
Citation: Neupane, D., Osborne, S.L., Schneider, S.K., Ewing, P.M. 2025. Drought severity and duration effects oat yield and yield components. Agronomy Journal. 117(6). Article e70225. https://doi.org/10.1002/agj2.70225.
DOI: https://doi.org/10.1002/agj2.70225

Interpretive Summary: Drought is a significant challenge for growing oats, and understanding how different oat genotypes respond to drought, as well as their susceptibility to different levels and durations of drought, helps reduce yield losses. We tested two oat genotypes, Ajay and Hayden, at three different irrigation levels that achieved 40%, 60%, and = 85% of the soil's water holding capacity. Drought was initiated at the oat heading, flowering, and grain filling stages and continued until maturity. Grain yield decreased by about 23% and 41% under medium and low water levels compared to the highest water level. The biggest yield loss occurred when drought was initiated at the heading stage. Hayden outperformed Ajay under all drought conditions. Hayden produced more grain and was better hydrated. Ajay produced more tillers, panicles, and a higher root biomass than Hayden, but those did not improve yield during drought. We found that plants exposed to drought from heading until maturity are more susceptible than those experiencing drought from the flowering or grain-filling stages until maturity. Overall, selecting varieties such as Hayden, which has high water-use efficiency and stable yields under drought conditions, can improve oat production.

Technical Abstract: Drought is a major constraint for oat (Avena sativa L.) production, particularly during critical growth stages. Understanding genotype responses to drought stress and identifying sensitive periods are essential for improving resilience. We evaluated the effects of drought severity and duration on two oat genotypes, Ajay and Hayden, under greenhouse conditions. Treatments were severe drought: 40% of water holding capacity (WHC); moderate drought: 60% of WHC; and well-watered: = 85% of WHC. Treatments were imposed during the heading, flowering, and grain filling stages until harvesting. Overall grain yield decreased by 23% and 41.5% under moderate and severe drought conditions, respectively, compared to the well-watered condition. Hayden had higher grain yields, relative water content (RWC), and water use efficiency (WUE) than Ajay across all drought levels. Ajay showed higher root-to-shoot ratio (RSR), tiller number, and panicle number; however, these traits did not improve yield or leaf hydration under drought stress. Yield correlated strongly with yield components, such as panicle number and seed weight, compared to physiological traits, including SPAD chlorophyll index and RWC. Genotypes with high WUE and stable yields when exposed to drought during early reproductive stages should be prioritized in future research, which should directly measure performance under stress rather than rely on pre-maturity physiological indicators.