OICC Press Journal of Crop Nutrition Science 2538-2470 11 2 2025 06 30 Effect of Putrescine on Morpho-Physiological Characteristics, Cationic Ion Uptake, Root Crop production of Sugar Beet (Beta vulgaris) under Water Stress Condition 10.57647/jcns.2025.1102.08 EN Mehdi Abbaszadeh Department of Agricultural Science, Ma.C., Islamic Azad University, Mashhad, Iran. Reza Sadrabadi Haghighi Department of Agricultural Science, Ma.C., Islamic Azad University, Mashhad, Iran. Ali Bagherzadeh Department of Agricultural Science, Ma.C., Islamic Azad University, Mashhad, Iran. https://orcid.org/0000-0002-5499-0092 Amir Salari Department of Science and Water Engineering, Minab Higher Education Center, University of Hormozgan, Iran Seyed Mostafa Hoseini Mazinani Department of Agriculture, YI.C., Islamic Azad University, Tehran, Iran. Journal Article 2025 06 30 Background: Exogenous application of growth regulators like putrescine is considered an effective strategy to mitigate the adverse effects of environmental stresses and enhance Crop production. Objectives: This study aimed to investigate the effects of putrescine foliar application on yield, uptake of certain cationic ions, and morpho-physiological traits of Sugar beet. Methods: The experiment was conducted in spring 2020 and 2021 at the Dasht-e Gol agricultural complex in Torbat-e Heydarieh, Iran, under a semi-arid climate. This study employed a split-plot design arranged in a randomized complete block design (RCBD) with three replications. Irrigation treatments were applied at three levels in the main plots: full irrigation meeting 100% of sugar beet water requirements (I1), moderate water deficit at 75% (I2), and severe water deficit at 50% (I3). Subplots consisted of three levels of foliar application: putrescine at concentrations of 0, 0.5, and 1 mM. Results: The results showed that drought stress significantly affected all studied traits, and putrescine application effectively alleviated the negative effects of water stress. Among the treatments, full irrigation combined with 1 mM putrescine foliar application yielded the most favourable results, improving all tested traits compared to the control. However, under mild stress (I2) with putrescine application, morpho-physiological traits showed significant improvement, with white sugar yield increasing notably and showing no significant difference from full irrigation conditions. The use of 1 mM putrescine is recommended to enhance sugar beet response to water stress. In both stress treatments (75% and 50% water requirements), exogenous putrescine significantly reduced the negative impacts of stress on most tested traits. Putrescine treatments significantly (P<0.01) increased leaf Mg and Zn contents across all irrigation levels. Conclusion: This study demonstrated that exogenous putrescine application can enhance the quantitative and qualitative yield of sugar beet under water stress conditions, aligning with improvements in morpho-physiological traits, increased cationic ion uptake, and induction of crop defence responses. These findings, along with further research, highlight the practical value of polyamines, particularly putrescine, as an agricultural tool for managing drought stress in sugar beet production. Therefore, based on the final results, foliar application of 1 mM putrescine under moderate water deficit (75% water requirement) is recommended as an effective and advised method to significantly improve root yield, white sugar yield, and overall drought tolerance in sugar beet cultivation under arid and semi-arid conditions.