A field experiment took place during the 2024–2025 growing season on sunflower (Helianthus annuus L.) at the College of Education for Pure Sciences, Ibn Al-Haitham, University of Baghdad, Baghdad, Iraq. The said study aimed to evaluate the effects of water stress and foliar application of nano-titanium and nano-curcumin on the concentrations of enzymatic antioxidants (superoxide dismutase [SOD], peroxidase [POD], and catalase [CAT]) and non-enzymatic antioxidants—malondialdehyde (MDA). Subjection of sunflower plants to water stress was for five, 10, and 15 days, and for foliar application of nano-titanium concentrations at 50 and 100 mg L^-1, and after 72 hours with nano-curcumin concentrations at 25 and 75 mg L^-1 along with control treatment. The results showed significant differences among studied factors on the physiological traits of the sunflower. Regarding drought stress, substantial differences showed the best results appeared with the longest irrigation interval due to the highest sunflower tolerance to environmental stress conditions. The water stress for a period of 15 days combined with nano-titanium (100 mg L^-1) and nano-curcumin (25 mg L^-1) provided the highest activity levels of SOD, POD, CAT, and MDA.

Keywords: Sunflower (H. annuus L.), nano-titanium and nano-curcumin, water stress conditions, peroxidase, catalase, curcumin, superoxide dismutase

Key findings: Sunflower (H. annuus L.), with the application of nano-titanium and nano-curcumin, demonstrated physiological response through increased activities of SOD, POD, and CAT, as well as MDA under water stress conditions.