University of Tabriz Journal of Agricultural Science and Sustainable Production 2476-4310 Articles in Press 2027 07 22 The Response of Wheat to Foliar Application of Humic Acid and Nanochitosan under Dryland Condition The Response of Wheat to Foliar Application of Humic Acid and Nanochitosan under Dryland Condition 21479 10.22034/saps.2025.67989.3380 FA Maryam Mohamadi M.Sc. Student in agroecology, Department of Production Engineering and Plant Genetics, Razi University Mohsen Saeidi Associated professor, Department of Production Engineering and Plant Genetics, Razi University Leila Zarei Associated professor, Department of Production Engineering and Plant Genetics, Razi University Journal Article 2025 07 05 Since foliar application of biostimulants and organic matter can affect the yield and yield components of important crops such as wheat, this study carried out to investigate the response of wheat to foliar application of humic acid and nano chitosan under dryland conditions. The experiment was conducted as factorial in a randomized complete block design with three replications on Hashtrood bread wheat cultivar during 2023-2024 growing season. The experimental factors included foliar spraying of humic acid at three concentrations (0 as control, 5, and 10 g/L) and chitosan nanoparticles at three concentrations (0 as control, 250, and 500 ppm). The plants were sprayed with the mentioned factors in stem elongation and flowering stages. The results showed that humic acid and nano-chitosan application caused the increasing in wheat growth and yield related traits including plant height, number of spikes, number of grains per spike, 1000-grain weight, grain yield, catalase activity, and relative water content of leaves compared to the control treatment. A significant interaction of humic acid × nano-chitosan was observed for flag leaf area and ascorbate peroxidase enzyme activity. The highest grain yield was related to application of 10 g/l humic acid (2480.77kg/ha) and 500 ppm nano-chitosan (2480.77 kg/ha) that increased by 1.03% and 1.06% compared to the control treatment respectively. Yield increasing can be due to the improvement of leaf area and the tracking of the highest amount of light and relative water content of the leaf, Since foliar application of biostimulants and organic matter can affect the yield and yield components of important crops such as wheat, this study carried out to investigate the response of wheat to foliar application of humic acid and nano chitosan under dryland conditions. The experiment was conducted as factorial in a randomized complete block design with three replications on Hashtrood bread wheat cultivar during 2023-2024 growing season. The experimental factors included foliar spraying of humic acid at three concentrations (0 as control, 5, and 10 g/L) and chitosan nanoparticles at three concentrations (0 as control, 250, and 500 ppm). The plants were sprayed with the mentioned factors in stem elongation and flowering stages. The results showed that humic acid and nano-chitosan application caused the increasing in wheat growth and yield related traits including plant height, number of spikes, number of grains per spike, 1000-grain weight, grain yield, catalase activity, and relative water content of leaves compared to the control treatment. A significant interaction of humic acid × nano-chitosan was observed for flag leaf area and ascorbate peroxidase enzyme activity. The highest grain yield was related to application of 10 g/l humic acid (2480.77kg/ha) and 500 ppm nano-chitosan (2480.77 kg/ha) that increased by 1.03% and 1.06% compared to the control treatment respectively. Yield increasing can be due to the improvement of leaf area and the tracking of the highest amount of light and relative water content of the leaf,