University of Tabriz Journal of Agricultural Science and Sustainable Production 2476-4310 36 1 2026 04 20 Foliar Application of Cytokinin Hormone and Salicylic Acid on Morphological Traits, Yield Traits of Sunflower Drought Stress Foliar Application of Cytokinin Hormone and Salicylic Acid on Morphological Traits, Yield Traits of Sunflower Drought Stress 135 150 21430 10.22034/saps.2024.61745.3224 FA Foad Hossini Student, Department of Plant Production and Genetics Shahid Chamran University of Ahvaz Afrasiab Rahnama Ghahfarokhi Associate Professor, Department of Plant Production and Genetics Shahid Chamran University of Ahvaz Moosa Meskarbashee Department of Plant Production and Genetics Shahid Chamran University of Ahvaz, Ahvaz, Iran Journal Article 2024 05 21 Background and Objectives: Sunflower productivity is strongly influenced by water availability, especially under drought stress. Plant growth regulators such as cytokinins and salicylic acid can enhancestress tolerance and improve yield by stimulating physiological processes. This study aimed to evaluate the effects of different irrigation intervals and foliar application of cytokinins and salicylic acid on seed and oil yield of sunflower under drought conditions. Materials and Methods: The experiment was conducted using a split-plot arrangement based on a randomized complete block design at Shahid Chamran University of Ahvaz during the 2021–2022 growin g season. Irrigation intervals were assigned to the main plots, while hormone treatments were allocated to subplots. The main factor consisted of three irrigation intervals (8, 12, and 16 days). The sub-factor included five hormone treatments: control (no hormone), cytokinin at 25 and 50 µmol. L-1, and salicylic acid at 200 and 400 mmol. L-1. Results: Increasing the irrigation interval from 8 days to 12 and 16 days led to a significant reduction in plant height, stem diameter, number of seeds per plant, 1000-seed weight, seed yield, biomass yield, oil yield, and oil percentage, while empty seeds increased under water deficit conditions. Results indicated the negative impact of prolonged irrigation intervals on sunflower productivity. However, the application of plant growth regulators partially alleviated these adverse effects. Under the 16-day irrigation intreval, seed yield increased by 69%, 72%, 37%, and 64% with the application of cytokinin at 25 and 50 µmol. L-1 and salicylic acid at 200 and 400 mmol. L-1, respectively, compared with the control treatment. Furthermore, the application of cytokinin at 50 µmol. L-1 under irrigation intervals of 8, 12, and 16 days increased seed yield by 33%, 16.5%, and 72%, respectively. Similarly, oil yield was improved by 33.5%, 19.5%, 50%, and 24% under the same conditions compared with hormone-deficit plants, highlighting the positive role of cytokinin in yield performance under both optimal and drought stress conditions. Conclusion: Cytokinin and salicylic acid can be considered effective strategies for improving the allocation of photosynthetic assimilates, seed yield, and oil yield in sunflower under both optimal irrigation and drought stress conditions. Although both hormones showed beneficial effects, cytokinin at a concentration of 50 µmol. L-1 was the most effective. Background and Objectives: Sunflower productivity is strongly influenced by water availability, especially under drought stress. Plant growth regulators such as cytokinins and salicylic acid can enhancestress tolerance and improve yield by stimulating physiological processes. This study aimed to evaluate the effects of different irrigation intervals and foliar application of cytokinins and salicylic acid on seed and oil yield of sunflower under drought conditions. Materials and Methods: The experiment was conducted using a split-plot arrangement based on a randomized complete block design at Shahid Chamran University of Ahvaz during the 2021–2022 growin g season. Irrigation intervals were assigned to the main plots, while hormone treatments were allocated to subplots. The main factor consisted of three irrigation intervals (8, 12, and 16 days). The sub-factor included five hormone treatments: control (no hormone), cytokinin at 25 and 50 µmol. L-1, and salicylic acid at 200 and 400 mmol. L-1. Results: Increasing the irrigation interval from 8 days to 12 and 16 days led to a significant reduction in plant height, stem diameter, number of seeds per plant, 1000-seed weight, seed yield, biomass yield, oil yield, and oil percentage, while empty seeds increased under water deficit conditions. Results indicated the negative impact of prolonged irrigation intervals on sunflower productivity. However, the application of plant growth regulators partially alleviated these adverse effects. Under the 16-day irrigation intreval, seed yield increased by 69%, 72%, 37%, and 64% with the application of cytokinin at 25 and 50 µmol. L-1 and salicylic acid at 200 and 400 mmol. L-1, respectively, compared with the control treatment. Furthermore, the application of cytokinin at 50 µmol. L-1 under irrigation intervals of 8, 12, and 16 days increased seed yield by 33%, 16.5%, and 72%, respectively. Similarly, oil yield was improved by 33.5%, 19.5%, 50%, and 24% under the same conditions compared with hormone-deficit plants, highlighting the positive role of cytokinin in yield performance under both optimal and drought stress conditions. Conclusion: Cytokinin and salicylic acid can be considered effective strategies for improving the allocation of photosynthetic assimilates, seed yield, and oil yield in sunflower under both optimal irrigation and drought stress conditions. Although both hormones showed beneficial effects, cytokinin at a concentration of 50 µmol. L-1 was the most effective.

https://sustainagriculture.tabrizu.ac.ir/article_21430_7fbd2e3c6bff0503aa10e84e295ff733.pdf