University of Tabriz Journal of Plant Physiology and Breeding 2008-5168 15 2 2025 12 01 Assessment of drought-related traits for rainfed wheat under current and future climates 309 338 21193 10.22034/jppb.2025.69279.1384 EN Seyyed Majid Alimagham Agronomy Group, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, 49138-15739, Iran. Afshin Soltani Agronomy Group, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, 49138-15739, Iran. 0000-0002-6941-4047 Vincent Vadez Institut de Recherche pour le Developement (IRD)– Université de Montpellier– UMR DIADE, 911 Avenue Agropolis, BP 64501, 34394, Montpellier Cedex 5, France; International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh, 502 324, India. Ebrahim Zeinali Agronomy Group, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, 49138-15739, Iran. Eskandar Zand Iranian Research Institute of Plant Protection, Agricultural Research Education and Extension Organization (AREEO), Tehran, Iran. Arezoo Abidi Agronomy Group, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, 49138-15739, Iran. Journal Article 2025 09 22 <strong>Objective: </strong>This research aimed to employ crop simulation modeling to identify key traits for improving water-limited yield (Yw) of rainfed wheat (<em>Triticum aestivum</em> L.) across Iran's diverse agro-climatic zones under current and projected future climates.<br /><strong>Methods: </strong>Using the Global Yield Gap Atlas (GYGA) upscaling protocol and the SSM-iCrop model, simulations were conducted for 32 reference weather stations (RWSs) representing 72% of Iran's national rainfed wheat area. Historical (2000–2015) and future (2041–2060; RCP4.5, +1.9 °C, 500 ppm CO₂) climate scenarios were analyzed to evaluate the impact of modifying physiological traits.<br /><strong>Results</strong>: Under the current climate, the national mean simulated Yw was 2.02 t ha⁻¹, ranging from 1.04 to 4.41 t ha⁻¹. Future climate increased mean Yw to 2.87 t ha⁻¹ (range: 1.54–5.33 t ha⁻¹), due to CO₂ fertilization and accelerated development, alleviating terminal drought. Trait analysis revealed that increasing the grain-filling duration by 20% was the most effective and consistent strategy, boosting national mean yield by 0.30 t ha⁻¹ (current climate) and 0.47 t ha⁻¹ (future climate) in high-rainfall Caspian Sea zones. Conversely, shortening the vegetative phase by 20% increased yields by up to 0.1 t ha⁻¹ in terminal-drought regions of the Zagros Mountains but reduced yields in eastern and northeastern Iran, with negative impacts intensifying under future climate. Decreasing phyllochron provided modest yield gains (>5% in 7 RWSs) under the current climate, but its benefits diminished under future warming. Increasing radiation use efficiency had a limited impact under both climate conditions. Spatial analysis showed the primary key trait was extending grain-filling for 13 RWSs (current) and 16 RWSs (future), while shortening the vegetative phase was key for 11 and 12 RWSs, respectively. Critically, in 9 RWSs across western/northwestern Iran, the optimal trait shifted with climate change, underscoring strong G×E interactions.<br /><strong>Conclusion: </strong>Breeding for enhanced grain-filling duration offers a robust, climate-resilient strategy for most parts of Iran. In contrast, manipulating vegetative growth duration requires precise, region-specific targeting due to its variable and sometimes negative effects. These results provide a spatially explicit blueprint for trait-based breeding to enhance the productivity and climate resilience of Iran's rainfed wheat systems.<br />  https://breeding.tabrizu.ac.ir/article_21193_b1ba3ef5c79a51eab0647a03f91532ec.pdf