The conduct of a field trial on oat (Avena sativa L.) transpired during the crop season of 2020–2021 at the District Seddat Al-Hindiyya, Al-Mahnawiyah region, Babylon Governorate, Iraq. The latest study aimed to evaluate oat cultivars’ response based on their growth and yield under water stress conditions and identify the drought-tolerant genotypes. The experiment in a randomized complete block design (RCBD) had a split-plot arrangement, two factors, and three replications. The main plots included three levels of water stress, i.e., depletion of available water by 50% (D1), 60% (D2), and 70% (D3), while the sub-plots included four oat cultivars, namely, Shefa’a, Oats-11, Gouda, and Carlop. The results showed the control treatment (with 50% depleted available water) proved superior in oat growth and related traits, i.e., plant height, flag leaf area, chlorophyll content, relative water content, panicles m², seeds per panicle, 1000-seed weight, and grain yield with averages, reaching 98.76 cm, 43.78 cm², 48.58 SPAD, 77.24%, 631.5 panicles m^-2, 61.17 grains panicle^-1, 42.94 g, and 16.11 t ha^-1, respectively, compared with the D3 irrigation treatment, with values for above traits showed a significant decline: 93.97 cm, 30.05 cm², 34.47 SPAD, 65.75%, 340.3 panicles m^-2, 46.42 grains panicle^-1, 31.51 g, and 4.54 t ha^-1, respectively. The oat cultivar Shefa’a was considerably superior, leading the majority of growth and yield traits compared with other cultivars. The results confirmed and recommended growing the oat cultivar Shefa’a under dry and semi-arid environments.

Keywords: Oat (Avena sativa L.), cultivars, water stress conditions, drought tolerance, growth and yield traits, physiological parameters

Key findings: The depletion of 50% of available water excelled other water regimes (available water depletion of 60% and 70%) in oat growth and yield-related traits. The oat cultivar Shefa’a also leads in grain yield compared with other cultivars under all the water regimes.