Zero tillage enhances cold stress tolerance and yield stability in dryland wheat

Cold stress limits rainfed wheat productivity. We combined a cold−room assay (+4 → −15 °C) with a two−year split–split plot field trial to test whether zero tillage (ZT) and sowing date improve cold tolerance across bread and durum cultivars. ZT, especially with September sowing, enhanced PSII performance (higher ETo/RC, Fv/Fm, Fv/Fo; lower ABS/RC and Fo/Fm), increased antioxidant activity (SOD, APX, CAT), and reduced H 2 O 2 and MDA, leading to higher and more stable grain yield. Winter cultivars sustained pigments and antioxidant defense better than spring types. These results position ZT + early sowing as a practical, climate−smart strategy to buffer cold stress and stabilize yields in drylands.