دانشگاه اصفهان علوم زیستی گیاهی 3041-9603 17 1 2025 05 22 Improving the Growth and Physiological Characteristics of Tomato (Solanum lycopersicum L.) by Optimizing the Concentration of Iron Oxide Nanoparticles (Fe₃O₄ NPs) in Foliar Spray بهبود ویژگی‌های رشد و فیزیولوژیکی گوجه‌فرنگی (Solanum lycopersicum L.) با بهینه‌سازی غلظت نانو ذرات اکسیدآهن (Fe₃O₄ NPs) در محلول‌پاشی برگی 55 76 29888 10.22108/ijpb.2025.146096.1415 FA راضیه رحمتی زاده گروه زیست شناسی، دانشکده علوم، دانشگاه ارومیه حسین مظفری گروه اکولوژی، پژوهشگاه علوم و تکنولوژی پیشرفته و علوم محیطی، دانشگاه تحصیلات تکمیلی صنعتی و فناوری پیشرفته، کرمان 0000-0001-7642-6145 محمد جواد آروین گروه باغبانی، دانشکده کشاورزی، دانشگاه شهید باهنر کرمان رشید جامعی گروه زیست شناسی، دانشکده علوم، دانشگاه ارومیه فاطمه نژاد علیمرادی گروه زیست شناسی، دانشگاه پیام نور، تهران Journal Article 2025 07 24 Iron nanoparticles, as one of the most widely used nanomaterials in modern agriculture, have garnered significant attention from researchers. These materials, with their unique chemical and physical properties, are capable of exerting notable effects on plant growth and performance. However, the utilization of Fe₃O₄NPs in the agricultural sector remains relatively limited. Therefore, in the present study, a factorial experiment was conducted in a completely randomized design with three replications and four treatment levels of Fe₃O₄ NPs (0, 25, 50, and 100 mg/L) applied via foliar spray on tomato plants. The results indicated that spraying with 25 mg/L Fe₃O₄ NPs improved growth characteristics, photosynthetic pigment content, nutrient elements, proteins, and antioxidant enzyme activity, while also reducing the content of MDA, H₂O₂, and GABA, compared to the control in tomato plants. Overall, the findings of this research clearly demonstrate the potential of Fe₃O₄ NPs as a micronutrient nanofertilizer, particularly in application via foliar spraying.<br /><strong> </strong> <strong> </strong><br /><strong>Introduction </strong><br />Nanotechnology, particularly the utilization of nanoparticles, offers innovative solutions for contemporary agricultural challenges, including the enhancement of plant growth and crop yield while preserving soil health (Usman et al., 2020; Feng et al., 2022). Among these, iron oxide nanoparticles (FeNPs) have garnered increasing attention due to the critical role of iron in plant physiological and biochemical processes, such as photosynthesis (El-Desouky et al., 2021; Góral et al., 2023). Iron deficiency, despite its abundance in soil (owing to insoluble and unavailable forms), poses a significant limitation to the growth of many plants, including tomatoes (Khan et al., 2020; Sagwal et al., 2023; Raiesi-Ardali et al., 2022). Tomato, as a vital agricultural crop, is particularly vulnerable to environmental stresses and nutrient deficiencies (Collins et al., 2022; Kaboré et al., 2022). Conventional methods of iron supply using chemical fertilizers necessitate innovative, cost-effective, and environmentally benign solutions due to their low absorption efficiency (Pasricha et al., 2021).<br />Currently, iron nanoparticles have emerged as a promising alternative for addressing iron deficiency (Raiesi-Ardali et al., 2022). However, research concerning their agricultural applications, specifically the effects of foliar application of Fe₃O₄ nanoparticles (Fe₃O₄ NPs) on enhancing plant growth, remains limited. This study was conducted to investigate the impact of foliar Fe₃O₄ NPs treatment on the morphological, physiological, and enzymatic traits of tomato plants, to determine the efficacy and optimal concentration of these nanoparticles for this crop.<br /><strong> </strong><br /><strong>Materials and Methods</strong><br />This experiment was conducted as a factorial experiment based on a completely randomized design with three replications. Following surface sterilization with a 1.0% sodium hypochlorite solution, seeds were rinsed and cultured in petri dishes. Three days post-germination initiation, seedlings were transferred to pots containing perlite and irrigated with half-strength Hoagland solution. For the synthesis of Fe₃O₄ nanoparticles, iron (III) chloride hexahydrate and iron (II) chloride tetrahydrate were dissolved in 100 mL of deionized water and maintained at 60°C. Subsequently, 10 mL of 25% ammonium hydroxide (NH₄OH) was added to the mixture (Rostami et al., 2018). For treatment application, Fe₃O₄ NPs were prepared at concentrations of 0, 25, 50, and 100 mg/L, sonicated, and sprayed onto plants at the four-leaf stage. At the end of the treatment period, stems and roots were separated and snap-frozen in liquid nitrogen.<br />Chlorophyll content was determined according to Lichtenthaler’s method (1987). Malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) levels were quantified using the methods described by Heath and Packer (1969) and Velikova et al. (2000), respectively. GABA was measured by the method of Baum et al. (1996), and protein content by the Bradford method (1976). The activities of superoxide dismutase (SOD) (Giannopolitis & Ries, 1977), ascorbate peroxidase (APX) (Nakano & Asada, 1981), and catalase (CAT) (Dhindsa et al., 1981) were assayed, along with elemental analysis using inductively coupled plasma mass spectrometry (ICP-MS). Results were presented as mean ± standard deviation. Statistical differences were analyzed using Microsoft Excel software and Two-Way Analysis of Variance (ANOVA). Duncan’s multiple range test was employed for mean comparisons, with a significance level set at p < 0.05.<br /><strong> </strong><br /><strong>Results and Discussion</strong><br />The results indicated that 25 mg/L Fe₃O₄ NPs increased dry weight, plant length, chlorophyll content, protein content, and the activity of antioxidant enzymes SOD, APX, and CAT. Concurrently, the levels of MDA, H₂O₂, and GABA showed a decrease. In contrast, 100 mg/L Fe₃O₄ NPs exhibited toxic effects, leading to a reduction in dry weight, plant length, chlorophyll content, and protein content, accompanied by an increase in MDA, H₂O₂, and GABA content. These findings corroborate the dual effects of iron oxide nanoparticles: at low concentrations, these nanoparticles can act as a growth stimulant, contributing to plant health by mitigating oxidative stress and modulating GABA accumulation. These positive effects are likely attributed to the supply of iron for enhanced activity of antioxidant enzymes such as APX and CAT, in which iron functions as a cofactor (Salehi Eskandari & Kharati Koopaei, 2020). In this study, 25 mg/L Fe₃O₄ NPs also led to an increase in the content of macronutrients (K, Ca, Mg) and micronutrients (Fe, Mn, Zn, Cu). Iron nanoparticles may stimulate the production of growth hormones like auxin and cytokinin, promoting cell division and improving the growth of aerial and root organs, which facilitates better nutrient absorption and contributes to overall plant growth (Divte et al., 2021). Iron nanoparticles can enhance nutrient uptake and distribution efficiency by regulating the expression of nutrient transporter genes (Yang et al., 2020) and, by reducing stress conditions, allocate more energy towards nutrient absorption and translocation (Feng et al., 2022). In this study, the 25 mg/L Fe₃O₄ NPs concentration provided a less stressful environment, leading to improved nutrient uptake and, consequently, greater plant growth and biomass.<br /><strong> </strong><br /><strong>Conclusion</strong><br />In this study, 25 mg/L Fe₃O₄ NPs demonstrated significant positive effects on the growth and physiology of tomato plants. The findings suggest that Fe₃O₄ NPs hold substantial potential as a novel and efficient alternative to traditional iron fertilizers in agriculture, and their foliar application can serve as a rapid and effective strategy for addressing nutritional deficiencies. However, further research under field conditions is deemed essential to validate these results on a larger scale and to gain a deeper understanding of the underlying mechanisms of action. نانو ذرات آهن به عنوان یکی از نانو مواد پرکاربرد در کشاورزی مدرن، توجه بسیاری از پژوهشگران را به خود معطوف کرده‌ است. این مواد، با ویژگی­های شیمیایی و فیزیکی منحصر به فردشان قادرند اثرات قابل توجهی بر رشد و عملکرد گیاهان داشته باشند. با این­وجود، استفاده از Fe₃O₄ NPs در بخش کشاورزی هنوز نسبتاً محدود است. بنابراین در پژوهش حاضر، آزمایشی به صورت فاکتوریل در قالب طرح کامل تصادفی در 3 تکرار و 4 سطح تیماری Fe₃O₄ NPs (0، 25، 50 و 100 میلی­گرم در لیتر) توسط محلول­پاشی برگی بر گوجه فرنگی صورت گرفت. نتایج نشان داد که غلظت 25 میلی­گرم در لیتر Fe₃O₄ NPs سبب بهبود صفات رشدی، محتوای رنگدانه­های فتوسنتزی، عناصر مغذی، پروتئین­ها و فعالیت آنزیم­های آنتی­اکسیدانی و کاهش محتوای MDA، H₂O₂ و GABA نسبت به شاهد در گوجه‌فرنگی شد. به­طور کلی یافته­های این پژوهش، پتانسیل بالقوه Fe₃O₄ NPs را به عنوان یک نانو کود ریزمغذی، به­ویژه در کاربرد توسط محلول­پاشی برگی به­طور واضح مشخص می­کند. https://ijpb.ui.ac.ir/article_29888_2f3aeede66ddc563260879875450a923.pdf