Synergistic effects of Fe nanocomplex and nitrophenolate-based biostimulant on growth and physiological performance of tomato seedlings

Vahid Tavallali; Mina Dashti Darvishzadeh

doi:10.1186/s12870-025-06930-y

. 2025 Jul 12;25:905. doi: 10.1186/s12870-025-06930-y

Synergistic effects of Fe nanocomplex and nitrophenolate-based biostimulant on growth and physiological performance of tomato seedlings

Vahid Tavallali ^1,^✉, Mina Dashti Darvishzadeh ²

PMCID: PMC12255147 PMID: 40646460

Abstract

This study examines the dose-dependent synergistic effect of foliar-sprayed iron nanocomplex (Fe NC; 0%, 0.2%, 0.4% w/v) and the nitrophenolate biostimulant Atonik (0, 125, 250 ppm) on tomato (Solanum lycopersicum) seedlings under controlled greenhouse conditions. This novel approach integrates nanotechnology and green biostimulants to enhance plant growth and physiological performance, marking a new direction of interest compared to conventional farming. At 30 days post-treatment, the optimum blend (0.4% Fe NC + 250 ppm Atonik) significantly enhanced growth indicators compared to the control: stem length (+ 84.2%), root length (+ 179.9%), leaf number (+ 190.8%), stem girth (+ 124.1%), and dry weight (+ 173.6%). Physiological improvements included net photosynthesis (Pn: +44.2%), stomatal conductance (Gs: +257.1%), and intercellular CO₂ (Ci: +264.1%), and lower stomatal limitation (Ls: -72.6%). Biochemical estimation showed high concentrations of chlorophyll a (+ 48.7%), chlorophyll b (+ 79.0%), carotenoids (+ 122.2%), soluble proteins (+ 42.2%), and carbohydrates (+ 133.3%). Hormonal regulation showed enhanced gibberellic acid (GA: +60.5%) and auxin (IAA: +74.4%) but decreased abscisic acid (ABA: -38.1% in leaves). Stem nutrient loading was improved by N (+ 75.2%), P (+ 54.6%), K (+ 48.2%), Ca (+ 40.2%), Mg (+ 32.5%), and Fe (+ 93.3%). The aim of this study was to investigate the synergistic action of FeNC and nitrophenolate biostimulant (Atonik) on improving the performance of tomato seedling through combined physiological, biochemical and molecular mechanisms, and formulating an effective nano-biofertilizer mixture for sustainable agricultur. On the basis of these findings, future research would need to investigate the long-term effects of Fe NC and Atonik on fruit production and quality, and their use in various crop species for maximizing agricultural sustainability.

Keywords: Iron nanocomplex, Nitrophenolate-based biostimulant (Atonik), Tomato seedlings (Solanum lycopersicum), Photosynthetic efficiency, Nutrient uptake, Phytohormone modulation

Introduction

Iron (Fe) is an essential element for plant life, serving as a critical cofactor for enzymes involved in numerous physiological and metabolic functions. Beyond being a fundamental nutrient, iron plays a pivotal role in processes such as photosynthesis, nitrogen fixation, nitrate assimilation, respiration, hormone synthesis, and DNA formation [1]. Iron nanoparticles (NPs) possess distinctive characteristics including a greater surface-to-volume ratio, natural compatibility with biological systems, quantum confinement effects, elevated surface energy, and multiple catalytic abilities. These features make them valuable in numerous domains such asenvironmental science, healthcare, farming, and industrial applications [2–4]. In contrast to standard fertilizers, nano-fertilizers are anticipated to greatly enhance crop growth and yield, optimize fertilizer efficiency, decrease nutrient wastage, and lessen negative environmental impacts. These nano-fertilizers are proposed as viable solutions to address the limitations ofconventional agricultural chemicals [5]. The advantageous characteristics of NPs enhance the development of nanofertilizers incorporatingvarious chelating agents, thereby augmenting their beneficial qualities. Furthermore, these nanoparticles boost the solubility of iron and its accessibility toplants. Their distinctive features, such as a diminutive size and extensive surface area, contribute to improved physiological traits and increasedin crop yield [6]. It is crucial to recognize that the harmful effects of NPs resulting from aggregation and dissolution in the dispersing medium are influenced by the specific doses utilized for eachapplication [7]. Consequently, utilizing nanomaterials in their ideal concentrations demonstrates the effective application of NPs in agricultural fertilizers, leading to minimized adverse effects and enhanced crop yields. Kulikova et al., (2017) reported the use of iron-based materials stabilized with Lonardite HS, employing these polymers to facilitate the efficient transport of amorphous ferric ions into the foliage [8]. They determined that these nanofertilizers have the potential to serve as substitutes for synthetic chelates or to be incorporated into fertilizers containingnitrogen, phosphorus, and potassium. In a study conducted by Li et al., (2018), it was found that employing γ-Fe₂O₃ NPs can enhance both the chlorophyll levels and the root activity in seedlings of Citrus maxima [9]. Siva and Benita (2016) demonstrated that the uptake of NPs by ginger roots enhances the protein content and boosts the iron levels in the rhizome. Additionally, synthetic iron chelates are costly and lead to both direct and indirect harm, including heightened mobility of heavy metals [10] and increased uptake of radioactive metals [11]. Iron nano-chelates enhanced various aspects of vegetative growth, photosynthetic metrics, pigment levels, and essential oil (EO) production in Calendula officinalis, all while avoiding any harmful effects [12].

Atonik is classified as a synthetic biostimulant and is recognized by other names such as Asahi SL or Chapperone [13]. This compound is a water-soluble phenolic substance composed of 0.1% sodium 5-nitroguaiacolate, 0.2% sodium ortho-nitrophenolate, and 0.3% sodium para-nitrophenolate [14]. Previous research has demonstrated that the use of synthetic biostimulants increases maize yield [15], cotton [16], and oilseed rape [17] without impairing the nutritional quality. Atonik, also recognized as sodium nitrophenolate, is a widely acknowledged synthetic biostimulant known for boosting the production of crops such as cotton, soybean, and rice among others [16, 18]. Gulluoglu et al. (2006) [18] found that plants treated with biostimulants exhibited increased biomass accumulation, growth, and development. Nitrophenolate-based synthetic biostimulants have been shown to increase the biomass and growth of vegetable and oilseed crops. The inhibition of indole-3-acetic acid (IAA) oxidase activity and increased auxin levels are likelythe causes of this impact [14, 16] Thisensures that synthetic biostimulants applied topically exhibit a greater affinity forIAA receptors, thereby increasing auxin activity [17].

Tomato (Solanum lycopersicum L.) is a crucial model species for examining the characteristics of fruit-bearing vegetables. Notably, the ‘Micro-tom’ variety of cultivated tomatoes is extensively utilized in research focused on enhancing the quality of tomatoes, as well as in studies of their physiological and biochemical aspects. This popularity is attributed to its compact size, abbreviated growth cycle, and exceptional adaptability [19]. In addition, tomatoes are a great source of lycopene and various vitamins [20]. While previous research has examined how nutrient management and light duration affect the growth of tomato plants and the quality of their fruits separately, the interaction of varying levels of external iron and different light cycles on the physiological traits of tomatoes and the quality of the fruit is still unexplored [19]. To demonstrate the synergistic effects of Atonik and iron nanocomplexes (Fe NCs) on the growth and physiological characteristics of tomato seedlings, this study measured element concentration, soluble protein content, chlorophyll levels, photosynthetic rate, and phytohormones during key growth stages. While Fe NCs area promising alternative to traditional iron fertilizers, and Atonik is recognized for its biostimulant properties, few studies have investigated their combined impact on the complete development and physiological cycle of tomato seedlings. This research aims to fill that gap and provide a foundation for the future application of Atonik and iron nanoparticles in enhancing crop productivity and sustainability.

Materials and methods

Preparation of iron nanocomplex

The Fe nanocomplex (Fe NC) was purchased from Zist Nano Fanavaran Atiyeh Pajooh Co., (Fars, Iran). 8 mL of deionized water was stirred magnetically for a duration of 10 min at ambient temperature. 3 mL of distilled water and 1 mmol of Fe(NO₃)₃ were introduced into the mixture. The reaction was sonicated with an ultrasonic probe (85%) for 25 min. Nitrogen gas was bubbled through to remove O₂. The solvent was evaporated after cooling and the composite was vacuum-dried for 24 h. The characterization of Fe NC was presentedin our previous research [12]. As shown in the SEM images in Fig. 1a, b, the Fe NC synthesized arenanoscale and small in size. According to these images, this synthesis has been done well and the Fe NC do not exhibit agglomeration or condensation. It can be seen that the crystalline and monolithic structure is nearly achieved in theFe NC. In order to produce a stable aqueous solution, nanoparticles are combined with deionized water using ultrasonic waves (Ultrasonic Cleanser KQ2200B, 100 W, 40 kHz, Kun Shan Ultrasonic Instruments Co., Ltd, China) in a water bath kept at ambient temperature for 30 min. After that, tomato seedlings were sprayed with the produced nanoparticle suspensions at concentrations of 0, 0.2, and 0.4% W/V.

Fig. 1 — SEM image of Fe nanocomplex synthesized

Planting tomatoes in the greenhouse

50% Coco-Peat was combined with soil and placed in 2 kg pots. For the pot cultivation, tomato (Solanum lycopersicum var. azmeer) seeds were utilized, sourced from Seminis^®. Before planting, the seeds were positioned on moist filter paper within a Petri dish for 24 h. After this period, three seeds were carefully extracted from the dish and inserted into each pot. Following germination and true leaf emergence, one plant was kept per pot. Greenhouse conditions: Day/night temperatures at 24 ℃/18 ℃, 12-hour light/dark cycle, 40% relative humidity. Soil water was maintained at ~ 80% field capacity by frequent irrigation. Once the vegetative stagehad ended, the plants were harvested. To assess the influence of the synthetic Fe nanocomplex and Atonik (nitrophenolate-based biostimulate) on tomato seedlings, a factorial experiment was performed usinga completely randomized design. This approach incorporated two treatments: iron nanocomplex at concentrations of 0, 0.2, and 0.4% (W/V), and Atonik at doses of 0, 125, and 250 ppm. The initial foliar application was given to seedlings at25 days old, during the second true leaf stage. A subsequent foliar spray was administered 20 days afterthe first application. Additional details regarding the soil mixture can be found in Table 1, where macro and microelements were incorporated as needed as deemed necessary prior to seedling transplantation.

Table 1.

Some physical and chemical properties of the soil used in experiment

Texture	pH paste	EC_e (dS m⁻¹)	Total Nitrogen (%)	NaHCO₃₋ extractable P(mg Kg⁻¹ soil)	NH₄OAC-extractable K(mg kg soil⁻¹)	CEC (Cm_c kg⁻¹)	Organic mater (% OM)	Iron (mg kg⁻¹)
Loam	6.5	1.2	0.2	13.5	63	12	7	3

Open in a new tab

Plant growth measurement

Plant growth parameters, i.e., stem length and root length, were recorded using a ruler, while stem diameter was recorded using a vernier caliper. Leaf number was recorded weekly from the emergence of the first true leaf until the fifth week. Shoots and roots were oven-dried at 105 °C for 48 h and stored at 70 °C until constant weight after 30 days of treatment. Dry weight (DW) was measured on an electronic balance (± 0.1 g accuracy; model LA16001S, Sartorius, Germany).2.4. Measurement of leaf gas exchange parameters.

Net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO₂ concentration (Ci), and transpiration rate (Tr) was utilized by GFS-3000 and DUAL-PAM-100 synchronous measuring instrument (Heinz Walz, Effeltrich, Germany). On clear, sunny days with little wind, the measurement was taken at 9:00 and 11:00 in the morning. Photosynthetic parameters were measured at three intervals: 10, 20, and 30 days after the treatment application.

Chlorophyll and soluble protein content assay

Chlorophyll content

Using the methods described by Chazaux et al. (2022), the concentrations of total carotenoids (Car, comprisingboth xanthophyll and carotene), chlorophyll a (Chl a), and chlorophyll b (Chl b) were measured [21]. Freshly harvested second fully expanded leaf weighing 0.5 g were obtained from five similarly positioned plants at 30 days after treatment (DAT). These leaveswere then submerged in 25 mL of 95% (v/v) ethanol in the dark for a period ranging from 24 to 36 h, until the leaves became completely colorless at ambient temperature. Using a spectrophotometer (UV-2450, Shimadzu Corp., Japan), the absorbance of Chl a, Chl b, and Car at wavelengths of 470, 645, and 663 nm. Each pigment’s concentration was determined using the following formulas:

Soluble protein content

According to Bradford et al. (1976), the drying method utilizingCoomassie Brilliant Blue G-250 was used to analyze the amount of soluble protein [22]. To prepare the reaction solution, 100 mg of Coomassie Brilliant Blue G-250 was combined with 50 mL of 95% ethanol and 100 mL of 85% phosphoric acid, then brought up to a final volume of 1000 mL with distilled water. 0.3 g of fresh leaves was extracted in 6 mL of 0.05 M phosphate buffer at a pH of 7.8 in an ice bath, and the solution was centrifuged at 4000 rpm for ten minutes to remove the supernatant. A portion of the supernatant (0.1 mL) was mixed with 0.9 mL of deionized water and added to 5 mL of 0.1% Coomassie Brilliant Blue G-250, creating a uniform mixture over 5 min. The absorbance was subsequently recorded at 595 nm atfour weeks aftertreatments.

Measurement of soluble sugar

According to the study conducted by Shi et al. (2022) [23], leaf sample (0.5 g) was shaken in 5 mL of 80% ethanol at 80 °C for 2 h, cooled, and filtered. Residue was re-extracted using 5 mL ethanol (1 h, 80 °C), and combined extracts were purified by C18 column, concentrated (rotary evaporator), and membrane-filtered (0.45 μm). Soluble sugars were quantified by HPLC (Waters 600E system) with a carbohydrate column (35 °C) and mobile phase acetonitrile: water (75:25, v/v). Data was processed using Millennium software (Millipore).

Analysis of plant hormone levels

Tomato seedlings were harvested at 30 DAT, leaf/root samples flash-frozen in liquid nitrogen and freeze-dried. For determination of IAA and ABA, 0.5 g samples were ground in ice-chilled mortar, extracted in 10 mL 80% methanol (with 1 mM BHT) at 4 °C for 12 h, and centrifuged (13,000 × g, 10 min, 4 °C). Samples were analyzed by HPLC (Agilent 1100 system) on a ZORBAX Eclipse XDB C18 column (4.6 × 280 mm, 5 μm) under gradient elution (0.7 mL/min): solvent A (0.1% formic acid in water) and B (acetonitrile: methanol, 1:1), from 20% B (0–1 min) to 80% B (3 min) and to 20% B (3.5 min). For GA analysis, 0.5 g of fresh tissues were homogenized, extracted in 2 mL 80% methanol (4 °C overnight, 1 mM BHT), and centrifuged (10,000 × g, 15 min, 4 °C). The supernatants were cleaned-up with C18 Sep-Pak cartridges and analyzed by ELISA: samples and antibodies (50 µL each) were incubated (37 °C, 90 min) in 96-well plates, washed with PBS (0.01 M, pH 7.4), and absorbance at 490 nm determined [24].

Measurement of mineral elements

The Kjeldahl procedure and the molybdenum blue technique were used to measure the levels of total phosphorus (P) and nitrogen (N) [25, 26]. After diagestion with H₂SO₄ and H₂O₂, the amounts of potassium (K), calcium (Ca), magnesium (Mg), and iron (Fe) were measured using a flame atomic absorption spectrometer (Varian AA-880, Mulgrave, Victoria, Australia).

Statistical analysis

Each treatment involved three replicates, and the findings were expressed as mean ± standard deviation (SD). The experimental data underwent analysis through two-way ANOVA, followed by Duncan’s multiple comparison test (p < 0.05), utilizing the IBM SPSS Version 22 statistical software.

Results and discussion

Growth characteristics

The two-way ANOVA results (Table 2) demonstrated that FeNCs and the nitrophenolate-derived biostimulant Atonik each had significant individual effects (p < 0.001) on all of the growth factors of tomato seedlings, i.e., stem length, root length, number of leaves, stem diameter, and seedling dry weight. The Fe NC-Atonik interaction effect was also statistically significant (p < 0.05) in all the variables, indicating synergistic actions instead of simple additive responses. The F-values described highly significant effects in stem height (Fe NC: F = 132.87; Atonik: F = 469.84), root length (Fe NC: F = 98.92; Atonik: F = 142.86), leaf number (Fe NC: F = 245.74; Atonik: F = 187.93), stem diameter (Fe NC: F = 132.45; Atonik: F = 82.71), and dry weight (Fe NC: F = 312.45; Atonik: F = 282.11). The interactive terms were highly significant (F = 6.28–25.14 across parameters), thereby justifying that combined treatment of Fe NC and Atonik leads to certain growth responses not achievable by single treatments. These findings emphasize the importance of individual and interactive effects while designing growth improvement strategies in tomato seedlings. Figure 2 illustrates the impact of Fe NC and Atonik on the growth of tomato seedlings. As shown in Fig. 2-a, foliar application of 0.4% Fe NC combined with 250 ppm Atonik significantly increased tomato seedling stem height compared to the control, from 18.10 cm to 34.33 cm, representing a 84.20% increase. Similarly, root height increased by 179.94% from 3.34 cm to 9.35 cm, under the same treatment (Fig. 2-b). According to Fig. 2-c, the number of tomato leaf increased across all concentrations compared to the control, with the highest increase (190.80%) observed in the 0.4% Fe NC and 250 ppm Atonik treatment. Stem diameter also increased in all concentrations of Fe NC and Atonik compared to the control, with the highest increase (124.14%) recorded in the 0.4% Fe NC and 250 ppm Atonik treatment (Fig. 2-d). Among the treatments, the 0.2% Fe NC without Atonik and the 0.2% Fe NC with 125 ppm Atonik showed the lowest increases and were not significantly different from the control group.

Table 2.

Two-way analysis of variance (ANOVA) results on the effects of Fe NC and Atonik on the growth characteristics of tomato seedlings (stem height, root length, leaf number, stem diameter, and seedlings’ dry weight) were analyzed at a confidence level of 95%

Height of Stem	SOV	SS	DF	MS	F-Value	P-Value
	Fe NC	323.94	2	161.97	132.87	0.001*
	Atonik	1145.32	2	572.66	469.84	0.001*
	Interaction (Fe NCAtonik)	59.78	4	14.94	12.26	0.001*
	Error	21.94	18	1.22	-	-
	Total	1550.98	26	-	-	-
Height of Root	Fe NC	54.21	2	27.10	98.92	0.001*
	Atonik	78.34	2	39.17	142.86	0.001*
	Interaction (Fe NCAtonik)	6.89	4	1.72	6.28	0.002*
	Error	4.93	18	0.27	-
	Total	144.37	26	-	-	-
Leaf Number	Fe NC	1032.15	2	516.07	245.74	0.001*
	Atonik	789.32	2	394.66	187.93	0.001*
	Interaction (Fe NCAtonik)	204.78	4	51.19	24.38	0.001*
	Error	37.80	18	2.10	-	-
	Total	2063.05	26	-	-	-
Stem Diameter	Fe NC	0.157	2	0.078	132.45	0.001*
	Atonik	0.098	2	0.049	82.71	0.001*
	Interaction (Fe NCAtonik)	0.023	4	0.006	9.67	0.001*
	Error	0.011	18	0.0006	-	-
	Total	0.289	26	-	-	-
Seedling Dry Weight	Fe NC	1.832	2	0.916	312.45	0.001*
	Atonik	1.654	2	0.827	282.11	0.001*
	Interaction (Fe NCAtonik)	0.294	4	0.074	25.14	0.001*
	Error	0.053	18	0.0029	-	-
	Total	3.833	26	-	-	-

Open in a new tab

SS Sum of Squares, DF Degrees of Freedom, MS Mean Square

*Indicates significant differences at the 95% confidence level (α = 0.05)

In terms of seedling dry weight (Fig. 2-e), foliar application of Fe NC and Atonik increased plant dry weight at all concentrations. The treatments with 0.2% and 0.4% Fe NC with 250 ppm Atonik resulted in increases of 166.67% and 173.59%, respectively, with no significant differences observed between these values. However, the 0.2% Fe NC and 0.4% Fe NC treatments without Atonik did not show any significant difference compared to the control group.

Foliar application of Fe NC combined with Atonik significantly enhanced the growth parameters of tomato seedlings, including stem height, root height, leaf number, stem diameter, and seedlingdry weight. 30 days after treatment, visual examination of the tomato seedlings also corroborated the improvement in the growth parameter under the synergistic treatment of Fe NC and Atonik. Observably from Fig. 3, the seedlings that received 0.4% Fe NC and 250 ppm Atonik exhibited dramatically higher stem elongation, leaf growth, and overall biomass compared to the untreated control. The visual observation is again a further corroboration of the statistical outcomes discussed hereinabove. These results align with previous findings on the positive effects of Fe NC and Atonik on plant growth [27, 28]. For instance, Rehman et al. (2018) demonstrated that tomato plant growth can be significantly improved using nanofertilizers composed of organically coated Fe NC. This growth enhancement is attributed to the increased absorption efficiency and greater mobility of Fe NC, facilitated by their small size, large surface area, and high bioavailability [6] Numerous studies have shown that Fe NC significantly boosts the fresh and dry biomass of various crops, including rice, wheat, tomatoes, peanuts, soybeans, and spinach [29, 30]. Tombuloglu et al. (2024) further confirmed that low-frequency applications of Fe NC (once weekly) contribute to improved tomato growth [31]. Similarly, Elbasuney et al. (2022) reported that foliar sprays of Fe₂O₃ nanoparticles at concentrations of 10 µg/mL and 20 µg/mL improved several morphological characteristics in tomato plants, including root length (increases of 3.53% and 28.61%), shoot length (increases of 17.38% and 20.30%), and leaf count (increases of 20.39% and 23.30%) compared to the control group [32].

Fig. 3 — Visual comparison of tomato seedlings 30 days after treatment

In the current study, the nitrophenolate-based biostimulant Atonik similarly enhanced growth parameters in tomato seedlings (Fig. 2). Apart from the overall physiological effect of Fe NC and Atonik on tomato seedling growth, it is relevant to consider the underlying biochemical and molecular mechanisms that may be responsible for such enhancement. Recent evidence suggests that Fe NC not only enhances iron uptake but is also capable of affecting gene expression associated with iron homeostasis and stress responses and thus promote enhanced root and shoot development [33]. Besides, Atonik’s biostimulant activity as a nitrophenolate type is likely furthered to hormone signal network regulation, i.e., auxin and cytokinin pathways, which regulate cell division, elongation, and differentiation. Such hormonal control can be supplemented by increased micronutrient availability to optimize resource utilization within the plant so that growth becomes more efficient [34]. Apart from that, concomitant application might ease oxidative stress by upregulating antioxidant enzyme activities to balance the buildup of reactive oxygen species that otherwise limits seedling vigor under stressed conditions [31]. The unified physiological and molecular mechanism suggests that Fe NC and Atonik are not only growth promoters or nutrient providers but are regulators of complex regulatory networks governing plant growth and stress tolerance. These findings are consistent with our preliminary studies on Zataria multiflora, where Atonik also increased growth parameters [35]. Additionally, Kocira et al. (2017) found that two distinct bean varieties treated with Atonik showed greater seed weight and higher yields of pods and seeds [13]. Przybysz et al. (2014) further demonstrated that Atonik enhanced the growth and development of Arabidopsis thaliana and oilseed rape [17], while Djanaguiraman et al. (2005b) confirmed its positive effects on tomato plant growth [36]. Contrary to earlier studies suggesting that plant growth rates diminish with increasing nanoparticle concentrations [37], the current research demonstrates that even at higher concentrations applied via foliar spraying, tomato plants exhibited a significant boost in growth characteristics. The mechanism of action for the enhanced growth of tomato seedlings through the foliar application of Fe NC and Atonik involves several key processes. Firstly, Fe NC, due to its small size and high surface area, increases the bioavailability and uptake efficiency of iron, an essential micronutrient critical for chlorophyll synthesis and the activation of enzymes involved in photosynthesis and respiration [38]. This leads to improved vegetative growth and biomass production. Secondly, Atonik, as a biostimulant, promotes cell division and elongation, enhances nutrient absorption, and increases the plant’s tolerance to environmental stresses [39]. The combination of Fe NC and Atonik creates a synergistic effect, where Fe NC improves iron uptake, and Atonik enhances metabolic and photosynthetic activities, enabling more efficient utilization of nutrients. This interaction results in significant improvements in growth parameters such as stem height, root length, leaf number, and dry weight [27].

Leaf gas exchange parameters

The two-way ANOVA test (Table 3) showed that both Fe NC and Atonik treatments significantly enhanced (p < 0.001) all the leaf gas exchange characteristics of tomato seedlings, including net photosynthesis (Ps: Fe NC F = 98.45, Atonik F = 129.71), stomatal conductance (Gs: Fe NC F = 245.00, Atonik F = 180.00), internal CO₂ concentration (Ci: Fe NC F = 1452.80, Atonik F = 2678.93), stomatal limitation (Ls: Fe NC F = 245.24, Atonik F = 320.00), and transpiration rate (Tr: Fe NC F = 421.50, Atonik F = 553.50). Notably, they showed strong synergistic interactions (p < 0.05) among all the parameters, particularly Ci (F = 49.20), Ls (F = 26.19), and Tr (F = 39.00), suggesting that the combined treatment much better optimizes stomatal function and photosynthetic efficiency than the single treatment. As shown in Fig. 4-a, foliar spraying of Fe NC and Atonik significantly increased photosynthesis (Pn) in tomato leaf across all treated plants. During the first 10 days, the most pronounced increase in photosynthesis (28.32%) was observed in the 0.4% Fe NC and 250 ppm Atonik treatment compared to the control group. At 20 and 30 days, treatments with 0.2% Fe NC, 0.4% Fe NC, and 250 ppm Atonik also showed significant differences, with a 44.17% increase in photosynthesis compared to other treatments.

Table 3.

Two-way analysis of variance (ANOVA) results on the effects of Fe NC and Atonik on the leaf gas exchange parameters of tomato seedlings after 30 days (Ps, gs, ci, Ls and Tr) were analyzed at a confidence level of 95%

Ps	SOV	SS	DF	MS	F-Value	P-Value
	Fe NC	64.32	2	32.16	98.45	0.001*
	Atonik	84.72	2	42.38	129.71	0.001*
	Interaction (Fe NCAtonik)	12.46	4	3.12	9.53	0.001*
	Error	5.88	18	0.33	-	-
	Total	167.41	26	-	-	-
Gs	Fe NC	0.392	2	0.196	245.00	0.001*
	Atonik	0.287	2	0.144	180.00	0.001*
	Interaction (Fe NCAtonik)	0.045	4	0.011	13.75	0.001*
	Error	0.014	18	0.0008	-	-
	Total	0.738	26	-	-	-
Ci	Fe NC	1,452,800	2	726,400	1452.80	< 0.001*
	Atonik	2,678,933	2	1,339,467	2678.93	< 0.001*
	Interaction (Fe NCAtonik)	98,400	4	24,600	49.20	< 0.001*
	Error	9000	18	500	-	-
	Total	4,238,133	26	-	-	-
Ls	Fe NC	0.412	2	0.206	245.24	< 0.001*
	Atonik	0.538	2	0.269	320.00	< 0.001*
	Interaction (Fe NCAtonik)	0.087	4	0.022	26.19	< 0.001*
	Error	0.015	18	0.0008	-	-
	Total	1.052	26	-	-	-
Tr	Fe NC	16.85	2	8.43	421.50	< 0.001*
	Atonik	22.14	2	11.07	553.50	< 0.001*
	Interaction (Fe NCAtonik)	3.12	4	0.78	39.00	< 0.001*
	Error	0.36	18	0.02	-	-
	Total	42.47	26	-	-	-

Open in a new tab

SS Sum of Squares, DF Degrees of Freedom, MS Mean Square

*Indicates significant differences at the 95% confidence level (α = 0.05)

Stomatal conductance (Gs) in tomato leaf also increased following foliar application of Fe NC and Atonik, as illustrated in Fig. 4-b. Throughout the 10, 20, and 30-day periods, the most significant enhancement (257.14%) in Gs was observed in the 0.4% Fe NC and 250 ppm Atonik treatment, which consistently outperformed the control group. Similarly, intercellular CO₂ concentration (Ci) in tomato leaf increased (264.12%) in response to Fe NC and Atonik application, following a trend comparable to that of Pn and Gs (Fig. 4-c). These results demonstrate that foliar spraying of Fe NC and Atonik not only enhances photosynthetic activity but also improves stomatal conductance and CO₂ utilization, contributing to overall plant growth and productivity.

The term “stomatal limitations” (Ls) refers to the restricted diffusion of CO₂ through stomata into the intercellular spaces of leaf. In this study, foliar spraying with Fe NC and Atonik reduced Ls in all treatments compared to the control. The maximum reduction (72.62%) in Ls was observed in the 0.2% and 0.4% Fe NC treatments combined with 250 ppm Atonik, with no significant differences between these two treatments (Fig. 4-d). Additionally, the transpiration rate (Tr) of tomato seedling leaf increased in all treatments compared to the control. However, the 0.2% and 0.4% Fe NC treatments with 250 ppm Atonik did not show significant differences in Tr (Fig. 4-e).

Through photosynthesis, plants convert carbon dioxide (CO₂) and water (H₂O) into organic matter, which is stored as carbohydrates, proteins, and other essential nutrients to support normal growth and development [40] Iron plays a critical role in enhancing photosynthetic efficiency, particularly by influencing stomatal conductance. Treatment with exogenous Fe NCs has been shown to promote plant growth and increase photosynthetic rates, likely due to enhanced rubisco activity and the accumulation of potassium and phosphorus in leaf, which reduces resistance to photosynthetic signals [12] Elevated CO₂ levels enhance carbon availability in leaf, leading to increased rubisco activity and higher photosynthetic rates. Additionally, foliar application of iron can increase superoxide dismutase (SOD) activity, mitigating the adverse effects of reactive oxygen species (ROS) generated under high-light conditions. This results in higher chlorophyll content and, consequently, an increased net rate of CO₂ assimilation [41]. Certain SOD isoforms in plants depend on iron for activation, as demonstrated by studies where exogenous Fe₂O₃ nanoparticles increased the net CO₂ assimilation rate in Catharanthus roseus [42] The concentration of CO₂ directly influences the rate of photosynthesis, with elevated levels enhancing carbon integration into carbohydrates during light-independent reactions, thereby boosting photosynthesis until another factor becomes limiting.

Foliar application of Fe NC and Atonik to tomato plants increased photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO₂ concentration (Ci), and transpiration rate (Tr), while reducing stomatal limitation (Ls). Iron is a crucial element for chlorophyll production and a key component of various enzymes. Iron deficiency reduces chlorophyll content, thereby decreasing photosynthetic rates [43]. The application of iron nanoparticles (Fe NC) enhances photosynthetic activity and increases bioavailable iron levels within plants [44]. These findings suggest that foliar spraying of Fe NC and Atonik not only boosts photosynthetic rates but also extends the duration of active photosynthesis, potentially supporting the generation of organic matter required for bud differentiation. These observations are consistent with recent studies that emphasize how nanofertilizers and biostimulants contribute to the enhancement of physiological functions in plants and their overall development [45]. The rise in the rate of photosynthesis can be linked to the increased availability of iron, an essential micronutrient crucial for the formation of chlorophyll and the transfer of electrons during photosynthesis [46]. The collaborative effect of Fe NC and Atonik suggests that these substances work in tandem to improve nutrient absorption and metabolic functions, resulting in more effective photosynthesis [47]. This aligns with findings that indicate Fe NC and biostimulants enhance chlorophyll levels and enzyme performance, thereby promoting photosynthetic activity. The observed enhancements in Gs and Ci reflect better gas exchange and CO₂ usage in the leaf of tomatoes. This improvement likely stems from the capability of Fe NC and Atonik to optimize both stomatal performance and nutrient access, as indicated by recent research [48, 49]. The reduction in Ls related to stomata supports the concept that these treatments facilitate CO₂ diffusion into the mesophyll, thus increasing the efficiency of photosynthesis. Moreover, the elevated transpiration rates indicate that there is an improved movement of water and nutrients, which is vital for the growth and productivity of plants [50]. The combined benefits of Fe NC and Atonik on Ps, Gs, and Ci illustrate their potential to enhance plant growth and yield. These results coincide with recent investigations showing a substantial improvement in plant growth and resilience to stress when using both nanofertilizers and biostimulants together [47]. In summary, these findings highlight the significance of effectively utilizing Fe NC and Atonik in the cultivation of tomatoes to improve photosynthetic capacity, nutrient absorption, and water efficiency.

Research by Zhang et al. (2023) demonstrated that treating tomatoes with varying concentrations of Fe chelate resulted in significant variations in Pn, Gs, Ci, and Tr, with values highly dependent on Fe chelate concentration. In our study, we observed an upward trend in Pn, Gs, Ci, and Tr, alongside a downward trend in Ls, following the application of different concentrations of Fe NC and Atonik [19]. Tombuloglu et al. (2024) also reported significant improvements in photosynthetic parameters in tomato seedlings treated with Fe NC suspension (500 mg L⁻¹) compared to untreated controls [31]. Similarly, Elbasuney et al. (2022) investigated the effects of two concentrations of iron oxide nanoparticles (10 and 20 µg/mL) applied as foliar sprays on tomato plants [32]. Their study revealed positive impacts on plant metabolism, emphasizing iron’s vital role in electron transfer and its involvement in photosynthetic and respiratory electron transport chains.

Przybysz et al. (2014) reported that Atonik application on oilseed rape, cucumber, and A. thaliana significantly elevated parameters related to plant gas exchange, such as photosynthetic intensity and stomatal resistance, compared to controls [17]. Our results align with previous findings on the positive effects of Atonik on leaf gas exchange parameters [17, 35, 51]. Consistent with our findings, Zrar et al. (2021) demonstrated that nitrophenolate compounds enhanced the photosynthesis process in two cultivars of Pisum sativum L., increasing CO₂ absorption in plastids [52]. This promoted the production of essential materials for new cell formation and contributed to improved vegetative growth in plants.

Chlorophyll, soluble protein and soluble sugar content

Table 4 indicates that Fe NC and Atonik significantly affected (p < 0.001) all the biochemical parameters determined in tomato seedlings, with very individual effects on chlorophyll a (Chl a: Fe NC F = 62.20, Atonik F = 89.20), chlorophyll b (Chl b: Fe NC F = 88.50, Atonik F = 124.50), carotenoids (Car: Fe NC F = 108.00, Atonik F = 192.00), soluble proteins (Fe NC F = 363.00, Atonik F = 529.50), and carbohydrates (Fe NC F = 381.00, Atonik F = 554.50). Highly significant interaction effects (p ≤ 0.001) among all parameters were established (Chl a F = 9.25; Chl b F = 14.00; Car F = 16.00; proteins F = 36.00; carbohydrates F = 43.00), indicating synergistic augmentation in photosynthetic pigments, protein synthesis, and carbohydrate accumulation when these treatments are applied together, thereby collectively augmenting photosynthetic efficiency and metabolic activity. The improvement in chlorophyll and carotenoid content may be attributed to the role of iron in the synthesis of chlorophyll and the development of photosynthesis activities. The increase in protein and carbohydrate content of Fe NC and Atonik treatments may be due to increased metabolic activities such as photosynthesis and respiration. Iron is an integral part for the synthesis of protein and enzymes involved in carbohydrate metabolism [53]. In addition, Atonik can stimulate growth hormone production and improve physiological processes, thus increasing protein and carbohydrate yields [17]. The blend of Fe NC and Atonik in advancing the physiological and biochemical characteristics of plants demonstrates the synergistic potential of both compounds. These actions are most probably because of enhanced iron absorption by the nanoparticles and the induction of metabolic processes by Atonik. The results underscore the importance of Fe NC and Atonik in enhancing biochemical processes in tomato seedlings. While both factors independently improve chlorophyll, protein, and carbohydrate levels, their interaction introduces a layer of complexity, suggesting that their combined application can lead to synergistic effects. This synergy may result in more efficient photosynthesis, improved metabolic activity, and enhanced growth, ultimately contributing to higher productivity in tomato seedling. These findings emphasize the need to consider not only the individual effects of Fe NC and Atonik but also their interactive potential when designing strategies to optimize plant performance. By leveraging the combined benefits of these factors, it may be possible to achieve greater improvements in biochemical and physiological processes, leading to more robust and productive tomato seedling.

Table 4.

Two-way analysis of variance (ANOVA) results on the effects of Fe NC and Atonik on the cholorophyl, soluble protein and carbohydrate content of tomato seedlings at a confidence level of 95%

Chl a	SOV	SS	DF	MS	F-Value	P-Value
	Fe NC	0.621	2	0.311	62.20	< 0.001*
	Atonik	0.892	2	0.446	89.20	< 0.001*
	Interaction (Fe NCAtonik)	0.182	4	0.046	9.25	0.001*
	Error	0.090	18	0.005	-	-
	Total	1.788	26	-	-	-
Chl b	Fe NC	0.354	2	0.177	88.50	< 0.001*
	Atonik	0.498	2	0.249	124.50	< 0.001*
	Interaction (Fe NCAtonik)	0.112	4	0.028	14.00	0.001*
	Error	0.036	18	0.002	-	-
	Total	1.000	26	-	-	-
Car	Fe NC	0.216	2	0.108	108.00	< 0.001*
	Atonik	0.384	2	0.192	192.00	< 0.001*
	Interaction (Fe NCAtonik)	0.064	4	0.016	16.00	0.001*
	Error	0.018	18	0.001	-	-
	Total	0.682	26	-	-	-
Protein	Fe NC	1.452	2	0.726	363.00	< 0.001*
	Atonik	2.118	2	1.059	529.50	< 0.001*
	Interaction (Fe NCAtonik)	0.286	4	0.072	36.00	< 0.001*
	Error	0.036	18	0.002	-	-
	Total	3.892	26	-	-	-
carbohydrate	Fe NC	15.24	2	7.62	381.00	< 0.001*
	Atonik	22.18	2	11.09	554.50	< 0.001*
	Interaction (Fe NCAtonik)	3.45	4	0.86	43.00	< 0.001*
	Error	0.36	18	0.02	-	-
	Total	41.23	26	-	-	-

Open in a new tab

SS Sum of Squares, DF Degrees of Freedom, MS Mean Square

*Indicates significant differences at the 95% confidence level (α = 0.05)

To demonstrate the effectiveness of organically modified Fe NC as a nano-fertilizer and Atonik, their effects on chlorophyll content (chlorophyll a and b) were investigated and compared with the control group (Table 5). With foliar spraying of Fe NC and Atonik, the 0.4% Fe NC and 250 ppm Atonik treatment showed the maximum significant difference in chlorophyll a content, with a 48.67% increase compared to the control. Regarding chlorophyll b content, all treatments with different concentrations showed significant differences compared to the control, and the 0.4% Fe NC and 250 ppm Atonik treatment exhibited the highest significant difference, with a 78.95% increase. Total chlorophyll content was also significantly affected by foliar spraying of Fe NC and Atonik. The 0.4% Fe NC and 250 ppm Atonik treatment showed a significant difference compared to the control, with a 54.79% increase in total chlorophyll content. Additionally, the ratio of chlorophyll a/b was calculated for all treatments. The 0.4% Fe NC and 250 ppm Atonik treatment showed the most significant difference compared to the control, while treatments such as 0.0% Fe NC and 125 ppm Atonik, 0.0% Fe NC and 250 ppm Atonik, and 0.2% Fe NC and 0.0 ppm Atonik did not show any significant difference with the control. Carotenoid content also showed the highest significant difference (122.22%) compared to the control in the 0.4% Fe NC and 250 ppm Atonik treatment. This increase might be attributed to enhanced stomatal conductance, transpiration rate, and/or changes in cell size and number [54]. Notably, treatment with Atonik at 125 ppm alone showed no significant difference compared to the control.

Table 5.

Effects of foliar application of Fe NC and Atonik on photosynthetic pigments concentration of leaf in tomato seedlings at 30-day after treatments. Different letters indicate significant differences between values (p˂0.05). Data are shown as mean ± sd of three replicates

Treatments		Chl a (mg g⁻¹ FW)	Chl b (mg g⁻¹ FW)	Chl (a + b) mg g⁻¹ FW	Chl a/b	Car (mg g⁻¹ FW)
Fe NC 0	A0	1.50 ± 0.02e	0.38 ± 0.01e	1.88 ± 0.03d	3.95 ± 0.06ab	0.18 ± 0.01f
	A125	1.77 ± 0.03 cd	0.43 ± 0.02d	2.20 ± 0.05bc	4.12 ± 0.08a	0.20 ± 0.01ef
	A250	1.82 ± 0.02c	0.46 ± 0.02c	2.28 ± 0.04bc	3.96 ± 0.06ab	0.24 ± 0.01d
Fe NC 0.2	A0	1.65 ± 0.03d	0.42 ± 0.03d	2.07 ± 0.03 cd	3.93 ± 0.08abc	0.22 ± 0.01de
	A125	1.88 ± 0.05c	0.49 ± 0.04c	2.37 ± 0.03b	3.84 ± 0.05bcd	0.28 ± 0.01c
	A250	2.09 ± 0.04b	0.56 ± 0.03b	2.65 ± 0.03a	3.73 ± 0.07cde	0.33 ± 0.01b
Fe NC 0.4	A0	1.70 ± 0.03d	0.46 ± 0.02c	2.16 ± 0.04bc	3.69 ± 0.06de	0.24 ± 0.01d
	A125	2.10 ± 0.04b	0.59 ± 0.04b	2.69 ± 0.05a	3.56 ± 0.07e	0.34 ± 0.02b
	A250	2.23 ± 0.05a	0.68 ± 0.03a	2.91 ± 0.04a	3.28 ± 0.07f	0.40 ± 0.02a

Open in a new tab

As shown in Fig. 5-a, foliar spraying of Fe NC with Atonik increased protein content in all treatments at different concentrations. The total protein content in the 0.4% Fe NC and 125 ppm Atonik treatment and the 0.4% Fe NC and 250 ppm Atonik treatment did not show any significant difference between them, with both treatments showing a 42.17% increase in protein content compared to the control. The study also examined the effect of Fe NC and Atonik treatments on carbohydrate levels (Fig. 5-b). According to the results, all treatments with different concentrations showed an increase in carbohydrate content. The 0.4% Fe NC and 250 ppm Atonik treatment showed the most significant difference compared to other treatments, with a 133.33% increase in carbohydrate content relative to the control. Meanwhile, the 0.2% Fe NC and 0.0 ppm Atonik treatment did not show any significant difference compared to the control.

Foliar application of Fe NC and Atonik significantly increased the levels of chlorophyll (a and b), proteins, and carbohydrates compared to the control group (Fig. 5). Iron deficiency, a common challenge in plant nutrition, impairs chlorophyll production, leading to interveinal chlorosis (yellowing between leaf veins) and stunted growth. In severe cases, chlorophyll loss may cause leaf to appear almost white, resulting in leaf drop and bud death [55]. The results of this study highlight the potential of Fe NC and Atonik to mitigate these deficiencies by enhancing chlorophyll synthesis, protein production, and carbohydrate accumulation, thereby improving overall plant health and productivity.

Iron is an essential micronutrient that is crucial for numerous physiological and biochemical functions in plants. It is essential for chlorophyll synthesis, carbohydrate production, nitrate and sulfate reduction, cell respiration, and nitrogen assimilation. Additionally, iron contributes to strengthening systemic resistance against both nutritional deficiencies and pathogens [1]. Its critical role in these processes highlights the importance of developing effective delivery systems to enhance iron bioavailability in plants, ensuring optimal growth, development, and stress resilience. Nanoparticles (NPs) have emerged as promising tools for improving nutrient uptake and utilization. They promote the production of organic compounds, such as proteins and chlorophyll, facilitating better plant growth [56]. For instance, studies have shown that iron oxide nanoparticles can significantly increase chlorophyll content in soybean plants [57]. Specifically, Fe₃O₄ nanoparticles at 75 mg.kg⁻¹ resulted in a 38% increase in chlorophyll levels compared to the control group treated with iron citrate. Additionally, in tomato shoots total protein levels increased by 38%, following treatment with Fe₃O₄ NPs at concentrations of 25 mg kg⁻¹ and 75 mg kg⁻¹ [37].

Iron (Fe) is a vital element required for the synthesis of chlorophyll and serves as a key constituent of numerous enzymes [19]. Elbasuney et al. (2022) reported that tomato plants treated with Fe₂O₃ nanoparticles (20 and 10 µg/mL) exhibited significant increases in chlorophyll a, chlorophyll b, carotenoids, total carbohydrates, and total soluble proteins [32]. Similarly, our findings align with previous research demonstrating that the application of Fe NCs substantially enhanced chlorophyll (a and b), carotenoids, proteins, and carbohydrates in tomatoes [28, 31, 37]. Li et al. (2017) found a threshold value for the positive regulation of Fe, and too high concentrations of Fe are not conducive to the accumulation of photosynthetic pigment in plants [58]. Consistent with this, Gao et al., (2022) showed that the stimulatory effect of foliar Fe fertilization on pigment accumulation was slightly attenuated by spraying 200 µM Fe-EDTA [59].

However, some studies report mixed results. For example, Wang et al. (2019) found no significant difference in sugar content between muskmelon (Cucumis melo) plants treated with NPs and the control group [60]. On the other hand, Iwaniuk et al. (2023) showed that nitrophenolate-based biostimulants effectively enhanced carbohydrate levels in wheat under biotic stress. Similarly [61], Niewęgłowski et al. (2024) demonstrated that a biostimulant containing sodium ortho-nitrophenol, sodium para-nitrophenol, and sodium 5-nitroguaiacol significantly increased protein and carbohydrate contents in two corn (Zea mays L.) varieties [62]. Comparable results were obtained by Abdel-Lattif et al. (2018), who highlighted the role of biostimulants in enhancing protein and starch levels [63].

Conversely, Kocira et al. (2017) reported a reduction in albumin and globulin levels in the Aura bean cultivar following the spray application of 0.1% Atonik [13]. Nonetheless, other studies, such as those by Zodape et al. (2010), have demonstrated that biostimulants effectively increase protein and starch levels in crops like green gram and fenugreek [64].

In conclusion, foliar application of Fe NC and Atonik has shown promising potential to enhance chlorophyll, protein, and carbohydrate levels in plants. While the results are generally positive, variability in outcomes across studies highlights the importance of tailoring treatments to specific crops and environmental conditions.

Plant hormone levels and mineral elements

Table 6 presents two-way ANOVA findings for the effect of Fe NC and Atonik on plant hormone content (gibberellic acid (GA), indole-3-acetic acid (IAA), and abscisic acid (ABA)) and mineral contents in tomato seedlings at a 95% confidence level. The data signify that Fe NC and Atonik, both individually and combined, significantly influence these parameters, which are significant factors in plant growth, development, and stress tolerance. Both treatments had extremely profound effects on promoting GA (F = 312.55 and 419.80, respectively; P < 0.001) and IAA (F = 315.20 and 475.00, respectively; P < 0.001). The interaction between them was also extremely significant (F = 51.05 and 61.90, respectively; P < 0.001), reflecting a synergistic effect on both hormones. Similarly, Fe NC and Atonik significantly affected ABA contents (F = 312.55 and 419.80; P < 0.001), with a significant interaction effect (F = 51.05; P < 0.001), indicating their role in stress response and stomatal functioning. These hormones directly regulate the gas exchange factors, photosynthesis, and transpiration. GA brings about cell growth and elongation, leading to increased leaf extension and leaf surface. An increased leaf surface area can augment the potential for gas exchange through the opening of more stomata and by providing increased surface area for CO₂ intake and O₂ release. The significant increase in GA content resulting from Fe NC and Atonik, individually as well as combined, shows that the treatments hold the capability of enhancing photosynthesis through improvingthe structure of leaves and stomatal number area [65]. IAA, which has the primary role of cell enlargement and division as well as leaf expansion, has the capability to produce a healthy leaf system with greater nutrient and water intake. Greater water absorption, in turn, can improve transpiration and gas exchange performance [66]. The elevated IAA levels brought about by Fe NC and Atonik, particularly in combination, indicate that these treatments can raise transpiration and photosynthesis at the same time through improved leaf development and water absorption. On the other hand, ABA as a stress hormone participates in regulation stomatal closureunder environmental stresses such as drought [67]. The decreased ABA levels due to Fe NC and Atonik alone and combined show that the treatments can increase the stress reaction of the plant and prevent undue loss of water. This targeted stomatal opening and closing is capable of establishing the best balance between CO₂ intake for photosynthesis and reduced transpiration during stress [68].

Table 6.

Two-way analysis of variance (ANOVA) results on the effects of Fe NC and Atonik on the plant hormone levels and mineral elements of tomato seedlings at a confidence level of 95%

Leaf GA	SOV	SS	DF	MS	F-Value	P-Value
	Fe NC	25890.50	2	12945.25	312.55	< 0.001*
	Atonik	34760.80	2	17380.40	419.80	< 0.001*
	Interaction (Fe NCAtonik)	8450.20	4	2112.55	51.05	< 0.001*
	Error	745.50	18	41.42	-	-
	Total	69846.00	26	-	-	-
Leaf IAA	Fe NC	12450.80	2	6225.40	315.20	< 0.001*
	Atonik	18760.50	2	9380.25	475.00	< 0.001*
	Interaction (Fe NCAtonik)	4890.30	4	1222.58	61.90	< 0.001*
	Error	355.20	18	19.73	-	-
	Total	36456.80	26	12945.25	-	-
Leaf ABA	Fe NC	25890.50	2	17380.40	312.55	< 0.001*
	Atonik	34760.80	2	2112.55	419.80	< 0.001*
	Interaction (Fe NCAtonik)	8450.20	4	41.42	51.05	< 0.001*
	Error	745.50	18	-	-	-
	Total	69846.00	26	-	-	-
Root GA	Fe NC	2450.50	2	1225.25	245.05	< 0.001*
	Atonik	3890.80	2	1945.40	389.08	< 0.001*
	Interaction (Fe NCAtonik)	1120.30	4	280.08	56.02	< 0.001*
	Error	90.00	18	5.00	-	-
	Total	7551.60	26	-	-	-
Root IAA	Fe NC	35680.50	2	17840.25	446.01	-
	Atonik	62450.30	2	31225.15	780.63	< 0.001*
	Interaction (Fe NCAtonik)	12340.80	4	3085.20	77.13	< 0.001*
	Error	720.00	18	40.00	-	< 0.001*
	Total	111191.60	26	-	-	-
Root ABA	Fe NC	1250.80	2	625.40	208.47	< 0.001*
	Atonik	2890.50	2	1445.25	481.75	< 0.001*
	Interaction (Fe NCAtonik)	450.30	4	112.58	37.53	< 0.001*
	Error	54.00	18	3.00	-	-
	Total	4645.60	26	-	-	-
Relative water	Fe NC	92.34	2	46.17	307.80	< 0.001*
	Atonik	78.12	2	39.06	260.40	< 0.001*
	Interaction (Fe NCAtonik)	12.45	4	3.11	20.73	< 0.001*
	Error	2.70	18	0.15	-	-
	Total	185.61	26	-	-	-
Stem Na	Fe NC	0.678	2	0.339	847.50	< 0.001*
	Atonik	0.892	2	0.446	1115.00	< 0.001*
	Interaction (Fe NCAtonik)	0.045	4	0.011	27.50	< 0.001*
	Error	0.007	18	0.004	-	-
	Total	1.622	26	-	-	-
Root Na	Fe NC	0.038	2	0.019	190.00	< 0.001*
	Atonik	0.025	2	0.0125	125.00	< 0.001*
	Interaction (Fe NCAtonik)	0.008	4	0.002	20.00	< 0.001*
	Error	0.002	18	0.0001	-	-
	Total	0.073	26	-	-	-
Stem N	Fe NC	4.82	2	2.41	602.50	< 0.001*
	Atonik	7.15	2	3.58	895.00	< 0.001*
	Interaction (Fe NCAtonik)	1.24	4	0.31	77.50	< 0.001*
	Error	0.07	18	0.004	-	-
	Total	13.28	26	-	-	-
Root N	Fe NC	3.45	2	1.725	1725.00	< 0.001*
	Atonik	4.82	2	2.410	2410.00	< 0.001*
	Interaction (Fe NCAtonik)	0.98	4	0.245	245.00	< 0.001*
	Error	0.018	18	0.001	-	-
	Total	9.268	26	-	-	-
Stem P	Fe NC	0.045	2	0.0225	225.00	< 0.001*
	Atonik	0.068	2	0.034	340.00	< 0.001*
	Interaction (Fe NCAtonik)	0.012	4	0.003	30.00	< 0.001*
	Error	0.002	18	0.0001	-	-
	Total	0.127	26	-	-	-
Root P	Fe NC	0.040	2	0.020	66.67	< 0.001*
	Atonik	0.060	2	0.030	100.00	< 0.001*
	Interaction (Fe NCAtonik)	0.010	4	0.0025	8.33	0.002*
	Error	0.005	18	-		-
	Total	0.115	26	-	-	-
Stem K	Fe NC	0.883	2	0.442	35.41	< 0.001*
	Atonik	2.762	2	1.381	110.75	< 0.001*
	Interaction (Fe NCAtonik)	0.310	4	0.077	6.21	0.002*
	Error	0.224	18	0.012	-	-
	Total	4.179	26	-	-	-
Root K	Fe NC	2.147	2	1.073	89.42	< 0.001*
	Atonik	5.892	2	2.946	245.50	< 0.001*
	Interaction (Fe NCAtonik)	0.423	4	0.106	8.83	0.003*
	Error	0.216	18	0.012	-	-
	Total	8.678	26	-	-	-
Stem Ca	Fe NC	0.294	2	0.147	36.75	< 0.001*
	Atonik	0.623	2	0.311	77.75	< 0.001*
	Interaction (Fe NCAtonik)	0.052	4	0.013	3.25	0.035*
	Error	0.072	18	0.004	-	-
	Total	1.041	26	-	-	-
Root Ca	Fe NC	1.214	2	0.607	75.88	< 0.001*
	Atonik	2.891	2	1.446	180.75	< 0.001*
	Interaction (Fe NCAtonik)	0.398	4	0.099	12.38	0.001*
	Error	0.144	18	0.008	-	-
	Total	4.647	26	-	-	-
Stem Mg	Fe NC	0.023	2	0.011	55.00	< 0.001*
	Atonik	0.056	2	0.028	140.00	< 0.001*
	Interaction (Fe NCAtonik)	0.008	4	0.002	10.00	0.002
	Error	0.0036	18	0.0002	-	-
	Total	0.090	26	-	-	-
Root Mg	Fe NC	0.097	2	0.048	48.00	< 0.001*
	Atonik	0.202	2	0.101	101.00	< 0.001*
	Interaction (Fe NCAtonik)	0.022	4	0.0055	5.50	0.004*
	Error	0.018	18	0.001	-	-
	Total	0.339	26	-	-	-
Stem Fe	Fe NC	0.334	2	0.167	167.00	< 0.001*
	Atonik	0.289	2	0.144	144.00	< 0.001*
	Interaction (Fe NCAtonik)	0.042	4	0.0105	10.50	0.001*
	Error	0.018	18	0.001	-	-
	Total	0.683	26	-	-	-
Root Fe	Fe NC	0.196	2	0.098	98.00	< 0.0001*
	Atonik	0.158	2	0.079	79.00	< 0.0001*
	Interaction (Fe NCAtonik)	0.025	4	0.006	6.00	0.003*
	Error	0.018	18	0.001	-	-
	Total	0.397	26	-	-	-

Open in a new tab

SS Sum of Squares, DF Degrees of Freedom, MS Mean Square

*Indicates significant differences at the 95% confidence level (α = 0.05)

Fe NC and Atonik both greatly increased GA in roots (Fe NC: F = 245.05; Atonik: F = 389.08; P < 0.001) with synergistic interaction effect (F = 56.02, P < 0.001). Similarly, they greatly enhanced IAA (Fe NC: F = 446.01; Atonik: F = 780.63; P < 0.001), with notable interaction (F = 77.13, P < 0.001), suggesting combined use could further enhance IAA, necessary for root development. ABA levels were also significantly impacted individually (Fe NC: F = 208.47; Atonik: F = 481.75; P < 0.001) and interactively (F = 37.53, P < 0.001), suggesting their role in root stress reactions. As shown in Fig. 6-a and -b, foliar spraying with different concentrations of Fe NC and Atonik resulted in significant differences in the levels of gibberellic acid (GA) and indole-3-acetic acid (IAA) hormones in the leaf of tomato seedlings. Among all treatments, the 0.4% Fe NC and 250 ppm Atonik treatment showed the most pronounced increase, with GA levels rising by 60.51% and IAA levels increasing by 74.36% compared to the control group. This treatment demonstrated the maximum significant difference relative to the control, highlighting the synergistic effect of higher concentrations of Fe NC and Atonik on hormone regulation. Additionally, the level of abscisic acid (ABA) in the leaf of tomato seedlings also showed a significant difference compared to the control group, with a notable decrease observed across all treatments (Fig. 6-c). Specifically, the treatments involving 0.2% and 0.4% Fe NC combined with 250 ppm Atonik did not differ significantly from each other but showed a 38.11% reduction in ABA levels, further underscoring the effectiveness of these treatments in modulating hormone balance.

In the roots of tomato seedlings, similar trends were observed for hormone levels, as illustrated in Fig. 6-d and -f. The treatments led to a significant increase in GA levels compared to the control, with the 0.2% and 0.4% Fe NC combined with 250 ppm Atonik treatments showing no significant difference between them but collectively resulting in a 51.01% increase in GA levels (Fig. 6-d). For IAA, the 0.4% Fe NC and 250 ppm Atonik treatment exhibited the most significant difference relative to the control, with a 163.73% increase in IAA levels in the roots (Fig. 6-e). Finally, all treatments significantly reduced ABA levels in the roots compared to the control group. The 0.4% Fe NC and 125 ppm Atonik treatment showed the highest reduction in ABA, with a 24.06% decrease, marking the most significant difference relative to the control (Fig. 6-f). These results collectively demonstrate that foliar application of Fe NC and Atonik not only enhances the levels of growth-promoting hormones like GA and IAA but also effectively reduces the stress-related hormone ABA, thereby promoting healthier growth and development in tomato seedlings.

Phytohormones are bio-constituents produced in trace quantities by plants, playing vital roles as signaling molecules to stimulate various aspects of crop growth and development. These hormones, such as gibberellic acid (GA), indole-3-acetic acid (IAA), and abscisic acid (ABA), regulate critical processes like growth promotion, stress response, and senescence. The application of nano Fe (Fe nanocomplex) has been shown to significantly modulate the levels of key phytohormones, including gibberellic acid (GA), auxin (IAA), and abscisic acid (ABA), in tomato seedlings (Solanum lycopersicum). Nano Fe enhances the biosynthesis and activity of growth-promoting hormones like GA and IAA while reducing the levels of ABA, a hormone associated with growth inhibition and senescence. Studies have demonstrated that nano Fe upregulates the expression of genes involved in GA and IAA biosynthesis, such as GA20ox and YUCCA family genes, leading to increased hormone levels and improved plant growth [69]. We observed that Fe nanocomplex significantly increased GA and IAA levels in tomato seedlings while reducing ABA levels, highlighting its ability to modulate hormone balance effectively. In agreement with our findings, Raiesi-Ardali et al. (2022) demonstrated that Fe₃O₄ nanoparticles (NPs) mitigate oxidative stress, modulate phytohormones, and promote growth in rice plants affected by iron deficiency [37]. Similarly, Mahmoud et al. (2022) reported that foliar application of Fe-NPs increased GA and IAA concentrations in broad bean leaf by 29.41% and 37.3%, respectively, while reducing ABA content by 44% compared to untreated plants [63]. NPs have been identified as key modulators of phytohormone activity. According to Bindraban et al. (2015), NPs influence plant hormone pathways, thereby enhancing plant resilience and growth under challenging conditions [70].

The reduction in ABA is particularly significant, as it indicates a shift toward growth promotion and reduced inhibition of developmental processes. Additionally, nano Fe has been shown to enhance the activity of enzymes like gibberellin 3-oxidase, which catalyzes the final step in GA biosynthesis, and inhibit IAA oxidase, which degrades auxins, thereby maintaining higher levels of these growth-promoting hormones [17]. Furthermore, nano Fe interferes with ABA biosynthesis by suppressing the expression of key ABA biosynthetic genes, such as NCED (9-cis-epoxycarotenoid dioxygenase), leading to reduced ABA accumulation [71]. These mechanisms collectively contribute to the hormonal balance that favors plant growth and development. Our findings align with these mechanisms, as Fe nanocomplex application not only enhanced GA and IAA levels but also significantly reduced ABA content in tomato seedlings, supporting its role as an effective tool for optimizing hormone regulation. Overall, the ability of nano Fe to modulate GA, IAA, and ABA levels underscores its potential as a sustainable solution for improving crop performance and development.

Nitrophenolate-based biostimulants, such as Atonik, have demonstrated significant efficacy in modulating phytohormone levels, including gibberellic acid (GA), auxin (IAA), and abscisic acid (ABA), in tomato seedlings (Solanum lycopersicum). The mode of action of nitrophenolates involves the regulation of key biosynthetic pathways and enzymatic activities associated with these hormones. For instance, Manal et al. (2015) demonstrated that foliar application of Atonik (100 ppm) significantly increased endogenous GA and IAA while decreasing ABA levels in cabbage plants compared to controls [72]. Przybysz et al. (2014) further explained that nitrophenolates, the active components of Atonik, interact with gibberellins to promote growth and inhibit IAA oxidase, thereby preserving higher auxin activity [17]. In agreement with these findings, our study revealed that foliar application of Fe NC combined with Atonik significantly increased GA and IAA concentrations while reducing ABA levels in both roots and stems of tomato seedlings. The reduction in ABA, a hormone known to inhibit growth and induce senescence, was more pronounced at higher Atonik concentrations, consistent with Przybysz et al. (2010) [14], who reported similar ABA reductions in A. thaliana treated with Atonik. Further analysis revealed a negative correlation between stem ABA content and stem Fe content (Fig. 7), with the lowest ABA levels observed in seedlings treated with 0.4% Fe NC and 250 ppm Atonik, followed by 0.4% Fe NC and 125 ppm Atonik. Pearson’s correlation analysis also indicated a positive relationship between stem Fe content and leaf IAA and GA₃ levels, suggesting a synergistic effect of Fe NC and Atonik in enhancing these growth-promoting hormones.

Fig. 7 — Effects of foliar application of Fe NC (nFe) and Atonik on (a) Na content in stem, (b) Na content in root (c) N content in stem, (d) N content in root, (e) P content in stem, (f) P content in root, (g) K content in stem, (h) K content in root, (i) Ca content in stem, (j) Ca content in root, (k) Mg content in stem, (l) Mg content in root, (m) Fe content in stem, (n) Fe content in root. Different letters indicate significant differences between values (p˂0.05). Data are shown as mean ± SD of three replicates

The mode of action of nitrophenolates in modulating these hormones can be attributed to their ability to upregulate genes involved in GA and IAA biosynthesis, such as GA20ox and YUCCA family genes, while downregulating ABA biosynthetic pathways [73]. Nitrophenolates also enhance the activity of enzymes like gibberellin 3-oxidase, which catalyzes the final step in GA biosynthesis, and inhibit IAA oxidase, which degrades auxins, thereby maintaining higher levels of these growth-promoting hormones. Additionally, nitrophenolates have been shown to interfere with ABA biosynthesis by suppressing the expression of key ABA biosynthetic genes, such as NCED (9-cis-epoxycarotenoid dioxygenase), leading to reduced ABA accumulation. These mechanisms collectively contribute to the hormonal balance that favors plant growth and development. In conclusion, the combined application of Fe NC and Atonik enhances plant growth by modulating key phytohormones through specific biosynthetic and enzymatic pathways, promoting auxin and gibberellin activity, and mitigating the adverse effects of ABA, supporting their use as effective strategies for improving crop performance.

Table 6 indicates the result of a two-way ANOVA with Fe NC and Atonik effects on relative water content (RWC) in tomato seedlings at a 95% confidence level. The result indicates that the two treatments showed significant effects on RWC individually (F-Value = 307.80 and 260.40, respectively; P-Value < 0.001). This confirms that individual factors work well to improve relative water content in plants, which is critical for maintaining water balance and tolerance to drought stress. The effect of Fe NC and Atonik interaction was also remarkable (F-Value = 20.73; P-Value < 0.001), with a potential for their application together to produce synergistic effects, further increasing RWC compared to when applied individually. This comparative increase in water content can help in more plant resistance to drought stress and better overall plant performance. Thus, the concurrent use of Fe NC and Atonik can be considered an extremely effective method for enhancing the water status of the plant and its resistance to environmental stresses. As demonstrated in Fig. (6-g), the foliar application of Fe NC and Atonik solutions showed significant differences compared to the control group across all treatments. The most significant difference (15.46%) was observed in the treatment with 0.4% Fe NC and 250 ppm Atonik. This significant enhancement can be credited to the synergistic effect of Fe NC and Atonik on stimulating plant water content and stress tolerance, whereby Fe NC possibly guaranteed nutrient acquisition and Atonik served as a growth promoter, thereby enhancing physiological processes to the fullest [27, 74]. Following the application of 0.4% FeNC − 125 ppm Atonik, a 14.31% increase in %RWC was observed. The lowest increase in %RWC was associated with the treatment of 0.0% FeNC − 125 ppm Atonik (9.47%). Foliar application of Fe NC and Atonik in the present experiment directly and substantially increased RWC of tomato seedlings. This kind of development in plant water status could lead to the decrease in the content of the stress hormone ABA [75]. ABA generally increases in response to drought and water deficiency conditions, leading to the closure of stomata in order to restrict water loss. However, the elevated RWC brought about by Fe NC and Atonik treatments alleviates water stress in the plant, thus the decreased need for ABA production [27]. The decrease in ABA content, therefore, is a secondary effect of improved water status, not its cause. This mechanism suggests that Fe NC and Atonik, by improving plant water status, not only induce drought stress tolerance but also may improve stomatal opening and gas exchange processes such as photosynthesis and transpiration by reducing ABA content [39]. All these combined impacts could result in improved plant growth and performance under stress and optimal conditions.

Atonik and Fe NC treatments, alone and combined, had a very significant (P < 0.05) effect on all root and stem parameters through the two-way ANOVA test. Na, N, and P content of stems significantly increased (P < 0.001) in high-level treatment interactions, whereas K was differently affected by Atonik as opposed to Fe NC. Na, N, and P content of the roots also significantly enhanced (P < 0.001) with significant synergies. The two treatments also substantially enhanced Ca, Mg, and Fe content in stems and roots (P < 0.001), with the majority of minerals showing significant interactions. These results indicate the conspicuous impact of Fe NC and Atonik, alone and together, on enhancing mineral uptake and plant growth.Foliar application of Fe NC and Atonik significantly increased the mineral content of sodium (Na), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and iron (Fe) in both the stems and roots of tomato seedlings compared to the control group. The sodium content in the stem (Fig. 7-a) exhibited the highest increase (25.94%) in the treatment of 0.0% FeNC and 250 ppm Atonik compared to control. The treatments of 0.2% FeNC and 250 ppm Atonik and 0.4% FeNC and 250 ppm Atonik showed a 17.45% and 13.68% increase in the stem sodium content, respectively. In contrast, the treatment of 0.4% FeNC and 0.0 ppm Atonik demonstrated a 13.68% reduction in sodium content in stem. The sodium concentration in the root tissue (Fig. 7-b) demonstrated a 6.98% increase in the 0.0% FeNC and 250.0 ppm Atonik treatment relative to the control group. Conversely, the application of 0.4% FeNC and 0.0 ppm Atonik resulted in a significant reduction of 27.91% in root sodium content. The results reveal that the addition of Atonik, particularly at higher concentrations (250 ppm), significantly enhances sodium uptake in the stem. Even in the combined treatments, sodium concentration in the stem increased, although these increases were smaller compared to the treatment without FeNCs. This suggests that FeNC is capable of reversing, partially, Atonik-sodium-increasing effect. Conversely, application of FeNC alone resulted in the significant reduction of both stem and root sodium content. This suggests a potential role of FeNC in reducing the level of sodium accumulation by affecting the ion transport processes or enhancing the effectiveness of sodium exclusion by the plant. In contrast, when FeNC was combined with Atonik, the inhibitory action was lost, perhaps due to the fact that Atonik had a predominant influence in controlling sodium uptake [17]. The activity of FeNC and Atonik interaction is tissue-specific and dose-dependent. Atonik prevails in the stem such that sodium uptake increases regardless of the concentration of FeNC. The degree of increase, however, diminishes as FeNC concentration rises, indicating a moderating influence of FeNC. Below the root, no Atonik (0.4% FeNC and 0.0 ppm Atonik) lowered sodium concentration significantly, but Atonik addition (0.0% FeNC and 250 ppm Atonik) produced a slight increasing effect. It thus seems that Atonik influence on sodium uptake is more significant below the stem than the root. These findings highlight the intricacy of the interaction between FeNC and Atonik in sodium regulation in plant tissues. Atonik, being a sodium biostimulant, presumably enhances sodium uptake through its physiological actions, which would be beneficial for plants under certain conditions (e.g., cell growth or osmotic adjustment) [15]. However, excessive sodium accumulation would become detrimental under salinity stress [45]. On the other hand, FeNC appears to play a defensive role by restricting sodium accumulation, possibly through pathways of increased ion selectivity, increased antioxidant activity, or alteration of membrane transporters [76]. Lastly, the dose-dependent action of Atonik and FeNC shows a balance between mitigation and sodium accumulation. Atonik promotes sodium accumulation (especially in the stem), but this can be offset by FeNC, particularlywhen absent. This highlights the necessity to balance sodium accumulation through the optimization of the combination of these treatments, in order to prevent possible toxicity, according to the plant’s particular needs and the conditions of the environment.

For instance, nitrogen content in the stems increased by 75.24%, while roots showed a 87.01% increase under this treatment (Fig. 7-c and -d). Notably, the 0.4% Fe NC and 250 ppm Atonik treatment did not differ significantly from the 0.4% Fe NC and 125 ppm Atonik treatment in terms of nitrogen accumulation in roots, suggesting that even lower concentrations of Atonik can be effective when combined with Fe NC.

Similarly, phosphorus content in tomato stems increased by 54.55% under the 0.4% Fe NC and 250 ppm Atonik treatment, while roots showed a 104.55% increase (Fig. 7-e and -f). This treatment also did not differ significantly from the 0.2% Fe NC and 250 ppm Atonik treatment in roots, indicating that moderate levels of Fe NC can still enhance phosphorus uptake when paired with higher Atonik concentrations. Potassium content followed a similar trend, with stems showing a 48.22% increase and roots a 132.19% increase under the 0.4% Fe NC and 250 ppm Atonik treatment (Fig. 7-g and -h). Again, this treatment did not differ significantly from the 0.2% Fe NC and 250 ppm Atonik treatment in roots, further highlighting the synergistic effects of Fe NC and Atonik.

Calcium content also exhibited significant improvements, with stems showing a 40.16% increase and roots a 86.59% increase under the 0.4% Fe NC and 250 ppm Atonik treatment (Fig. 7-i and -j). The stem results did not differ significantly from the 0.2% Fe NC and 250 ppm Atonik treatment, suggesting that even lower Fe NC concentrations can be effective when combined with higher Atonik levels. Magnesium content in stems increased by 32.5% under the 0.4% Fe NC and 250 ppm Atonik treatment, while roots showed a 56.67% increase (Fig. 7-k and -l). Interestingly, in the absence of Atonik, magnesium content in stems did not differ significantly from the control, emphasizing the critical role of Atonik in enhancing magnesium uptake. The 0.4% Fe NC and 250 ppm Atonik treatment did not differ significantly from the 0.4% Fe NC and 125 ppm Atonik treatment in roots, indicating that moderate Atonik levels can still be effective when combined with higher Fe NC concentrations.

Iron content in stems increased by 93.33%, while roots showed a 75% increase under the 0.4% Fe NC and 250 ppm Atonik treatments (Fig. 7-m and -n). In roots, this treatment did not differ significantly from the 0.4% Fe NC and 125 ppm Atonik treatment, further underscoring the effectiveness of combining Fe NC with Atonik for improving iron uptake. Overall, these findings demonstrate that foliar application of Fe NC and Atonik significantly enhances the acquisition of essential nutrients in tomato seedlings, with the 0.4% Fe NC and 250 ppm Atonik treatment consistently yielding the highest increases across all measured elements. This highlights the potential of these treatments to improve nutrient uptake and plant performance, particularly under suboptimal growing conditions.

The uptake and transport of nutrients are critical for plant growth and health maintenance, especially under challenging environmental conditions. The application of Fe NCs has been shown to significantly increase iron concentration in the leaf of almond trees, effectively restoring their growth and health. Numerous studies have highlighted that nano-iron particles are more efficient than traditional chelated iron fertilizers in delivering iron to plants [30]. Supporting these findings, our previous research demonstrated that Fe nanocomplexes substantially elevated the levels of essential nutrients such as calcium, zinc, iron, copper, and potassium in pistachio leaf under salinity stress [77]. Similarly, foliar application of iron chelate has been reported to significantly enhance the concentrations of zinc, potassium, calcium, magnesium, and iron in tomato fruits [19]. This suggests that iron fertilization not only promotes the uptake of these critical elements but may also exhibit synergistic effects, enhancing overall nutrient absorption in plants [78].

Recent studies have provided significant evidence on the impact of iron-based nanomaterials in enhancing nutrient uptake and plant growth. For instance, Wang et al. (2021) reported that the application of iron nanoparticles at various concentrations led to a notable accumulation of iron in the roots and leaf of rice plants compared to control groups [79]. These findings align with other observations indicating that foliar application of Fe NCs stimulates root growth (Fig. 2-b), which could explain the subsequent improvement in nutrient uptake. Additionally, iron nanoparticles play a key role in modulating mineral content within plants by regulating the expression of iron transport-related genes [80]. Collectively, these results highlight the multifaceted benefits of Fe NCs in improving plant growth, nutrient absorption, and stress resilience, making them a promising alternative to conventional iron fertilizers.

Our findings also confirmed the biocompatibility of Fe NCs for the accumulation of iron and other minerals in tomato seedlings. Consistent with these results, previous studies have shown that foliar application of nano-chelated iron enhances mineral uptake in cumin plants [81]. Another study reported that foliar application of a spinel nanocomposite (nMnZFe NC₂O₄) significantly increased the concentration of minerals in rice grains [82]. Similar reports by various researchers suggest the feasibility of using functionalized iron nanomaterials for the agronomic biofortification of various crops [83].

Moreover, the ability of nano-iron forms to penetrate plant tissues has been well-documented. Our study further revealed that Fe NCs impart beneficial effects, contributing to growth enhancement and iron biofortification in tomato seedlings. The application of this nanocomplex led to increased mineral concentrations in both stems and roots. Given these findings, future research could focus on understanding the molecular mechanisms underlying these improvements to develop effective strategies for biofortification and addressing iron deficiency in crops, ultimately contributing to improved human nutrition.

Nitrophenolate-based biostimulants, such as Atonik, have demonstrated significant potential in enhancing the acquisition of essential mineral nutrients—including zinc (Zn), magnesium (Mg), calcium (Ca), nitrogen (N), potassium (K), phosphorus (P), and iron (Fe)—in tomato seedlings (Solanum lycopersicum). These biostimulants improve nutrient uptake through multiple mechanisms, such as stimulating root growth, modulating nutrient transporter activity, and alleviating abiotic stress. For instance, nitrophenolates enhance root elongation, lateral root formation, and root hair density, thereby increasing the root surface area available for nutrient absorption [84]. They also upregulate genes encoding high-affinity nutrient transporters, such as NRTs (nitrate transporters), PTs (phosphate transporters), AKTs (potassium channels), Ca²⁺-ATPases, MGTs (magnesium transporters), IRT1 (iron-regulated transporters), and ZIPs (zinc-regulated transporters), which facilitate efficient nutrient uptake [85]. In agreement with our findings, Atonik significantly improved the acquisition of N, P, K, Ca, Mg, Fe, and Zn in tomato seedlings, likely due to its ability to enhance root development and nutrient transporter activity. Additionally, nitrophenolate-based biostimulants mitigate abiotic stresses, such as salinity, by maintaining ion homeostasis and enhancing antioxidant capacity, thereby ensuring uninterrupted nutrient uptake under stress conditions [86]. Our research further supports this, as Atonik application not only improved nutrient uptake but also enhanced the resilience of tomato seedlings to stress, promoting better growth and nutrient utilization. The synergistic effects of nitrophenolates with other biostimulants, such as humic acids, have also been reported to further enhance nutrient acquisition, particularly for micronutrients like Fe and Zn [87]. These findings align with our observations, highlighting Atonik as an effective tool for optimizing mineral nutrient acquisition in tomato seedlings. Overall, the ability of nitrophenolate-based biostimulants to improve nutrient uptake through root development, transporter modulation, and stress alleviation underscores their potential as sustainable solutions for enhancing crop productivity and resilience.

Finally, The Pearson correlation heatmap (Fig. 8) showed positive correlations among Fe NC, Atonik and stem height, root height, number of leaf, stem diameter, dry weight of tomato seedlings, Pn, Gs, Ci, chlorophyll (a, b), carotenoids, proteins and carbohydrates, GA and IAA hormones and all the minerals and elements studied in tomato stems and roots. In addition, there is a negative relationship with Fe NC, Atonik and Ls and the ABA hormone.

Previous studies have investigated the use of Fe NC [33] or Atonik [88] as an artificial stimulant on tomatoes. However, none of the studies have investigated the simultaneous use of the two together. Our results showed that the simultaneous use of a Fe NC and a nitrophenolate-based biostimulant (Atonik) can have much better results than using them individually.

Conclusions

This study demonstrates the significant synergistic effects of foliar application of iron nanocomplex (Fe NC) and the nitrophenolate-based biostimulant Atonik on the growth, physiological performance, and nutrient uptake of tomato seedlings (Solanum lycopersicum). The combined treatment of 0.4% Fe NC and 250 ppm Atonik resulted in the most pronounced improvements across various growth parameters, including stem height, root length, leaf number, stem diameter, and dry weight. Additionally, photosynthetic efficiency was markedly enhanced, as evidenced by increased net photosynthesis (Pn), stomatal conductance (Gs), and intercellular CO₂ concentration (Ci), alongside reduced stomatal limitation (Ls). The treatment also led to higher chlorophyll a and b content, carotenoid levels, and increased soluble protein and carbohydrate concentrations, indicating improved metabolic activity and energy storage.

Furthermore, the application of Fe NC and Atonik positively influenced phytohormone levels, with significant increases in gibberellic acid (GA) and auxin (IAA), and a reduction in abscisic acid (ABA), promoting growth and stress resilience. Nutrient uptake was also enhanced, with notable increases in nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and iron (Fe) levels in both stems and roots, highlighting the role of these treatments in improving nutrient acquisition and utilization. The findings underscore the potential of Fe NC and Atonik as sustainable alternatives to conventional fertilizers, offering a promising approach to enhance crop productivity, nutrient efficiency, and stress tolerance. Future research should focus on optimizing application protocols and exploring the molecular mechanisms underlying these synergistic effects to further advance their use in agricultural practices. Overall, this study provides a strong foundation for the integration of nanotechnology and biostimulants in modern agriculture to address global food security challenges.

Acknowledgements

The authors appreciate the administrative and technical support provided by the Department of Agriculture and Payam Noor University to achieve this research.

Abbreviations

Fe NC: Iron nanocomplex
NPs: Nanoparticles
Pn: Net photosynthesis
Gs: Stomatal conductance
Ci: Intercellular CO₂ concentration
Ls: Stomatal limitation
Tr: Transpiration rate
GA: Gibberellic acid
IAA: Indole-3-acetic acid
ABA: Abscisic acid

Authors’ contributions

Vahid Tavallali: Conceptualization, Methodology, Writing- Reviewing and Editing, Supervision. Mina Dashti Darvishzadeh: Data curation, Writing- Original draft preparation, Visualization, Investigation, Software.

Funding

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability

The data presented in this study are available on request from the authors.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Footnotes

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

References

1.Hell R, Stephan UW. Iron uptake, trafficking and homeostasis in plants. Planta. 2003;216:541–51. [DOI] [PubMed] [Google Scholar]
2.Sharma P, Holliger N, Pfromm PH, Liu B, Chikan V. Size-controlled synthesis of iron and iron oxide nanoparticles by the rapid inductive heating method. ACS Omega. 2020;5(31):19853–60. [DOI] [PMC free article] [PubMed] [Google Scholar]
3.Yang Y, Huang M, Qian J, Gao D, Liang X. Tunable Fe3O4 nanorods for enhanced magnetic hyperthermia performance. Sci Rep. 2020;10(1):8331. [DOI] [PMC free article] [PubMed] [Google Scholar]
4.Kornarzyński K, Sujak A, Czernel G, Wiącek D. Effect of Fe3O4 nanoparticles on germination of seeds and concentration of elements in Helianthus annuus L. under constant magnetic field. Sci Rep. 2020;10(1):8068. [DOI] [PMC free article] [PubMed] [Google Scholar]
5.Yoon HY, Lee JG, Esposti LD, Iafisco M, Kim PJ, Shin SG, et al. Synergistic release of crop nutrients and stimulants from hydroxyapatite nanoparticles functionalized with humic substances: toward a multifunctional nanofertilizer. ACS Omega. 2020;5(12):6598–610. [DOI] [PMC free article] [PubMed] [Google Scholar]
6.Zia-ur-Rehman M, Naeem A, Khalid H, Rizwan M, Ali S, Azhar M. Responses of plants to iron oxide nanoparticles. Nanomaterials in plants, algae, and microorganisms. Elsevier; 2018. pp. 221–38.
7.Kumar R, Ashfaq M, Verma N. Synthesis of novel PVA–starch formulation-supported Cu–Zn nanoparticle carrying carbon nanofibers as a nanofertilizer: controlled release of micronutrients. J Mater Sci. 2018;53(10):7150–64. [Google Scholar]
8.Kulikova NA, Polyakov AY, Lebedev VA, Abroskin DP, Volkov DS, Pankratov DA, et al. Key roles of size and crystallinity of nanosized iron Hydr (oxides) stabilized by humic substances in iron bioavailability to plants. J Agric Food Chem. 2017;65(51):11157–69. [DOI] [PubMed] [Google Scholar]
9.Li J, Hu J, Xiao L, Wang Y, Wang X. Interaction mechanisms between α-Fe2O3, γ-Fe2O3 and Fe3O4 nanoparticles and Citrus maxima seedlings. Sci Total Environ. 2018;625:677–85. [DOI] [PubMed] [Google Scholar]
10.Peng L, Qin P, Lei M, Zeng Q, Song H, Yang J, et al. Modifying Fe3O4 nanoparticles with humic acid for removal of Rhodamine B in water. J Hazard Mater. 2012;209:193–8. [DOI] [PubMed] [Google Scholar]
11.Means JL, Crerar DA, Duguid JO. Migration of radioactive wastes: radionuclide mobilization by complexing agents. Science. 1978;200(4349):1477–81. [DOI] [PubMed] [Google Scholar]
12.Tavallali V, Rahmati S, Bahmanzadegan A, Lasibi MJM. Variation in developmental and phytochemical characteristics of Calendula officinalis L. using foliar application of iron nanoparticles formed on hyaluronic acid. Sci Hort. 2024;323:112539. [Google Scholar]
13.Kocira A, Kocira S, Świeca M, Złotek U, Jakubczyk A, Kapela K. Effect of foliar application of a nitrophenolate–based biostimulant on the yield and quality of two bean cultivars. Sci Hort. 2017;214:76–82. [Google Scholar]
14.Przybysz A, Wrochna M, Slowinski A, Gawronska H. Stimulatory effect of Asahi SL on selected plant species. Acta Scientiarum Polonorum Hortorum Cultus. 2010;9(2):53–64.
15.Batool Z, Ishfaq M, Akbar N, Zulfiqar U, Anjum SA, Shafiq M, et al. Exogenous application of Atonik (sodium nitrophenolate) under skip irrigation regimes modulated the physiology, growth and productivity of Zea mays L. Arch Agron Soil Sci. 2023;69(12):2325–39. [Google Scholar]
16.Djanaguiraman M, Sheeba JA, Devi DD, Bangarusamy U. Response of cotton to Atonik and TIBA for growth, enzymes and yield. J Biol Sci. 2005;5(2):158–62. [Google Scholar]
17.Przybysz A, Gawrońska H, Gajc-Wolska J. Biological mode of action of a nitrophenolates-based biostimulant: case study. Front Plant Sci. 2014;5:713. [DOI] [PMC free article] [PubMed] [Google Scholar]
18.Gulluoglu L, Arİoglu H, Arslan M. Effects of some plant growth regulators and nutrient complexes on above-ground biomass and seed yield of soybean grown under heat-stressed environment. 2006.
19.Zhang Y, Liang Y, Han J, Hu X, Li X, Zhao H, et al. Interactive effects of iron and photoperiods on tomato plant growth and fruit quality. J Plant Growth Regul. 2023;42(1):376–89. [Google Scholar]
20.Dannehl D, Schwend T, Veit D, Schmidt U. Increase of yield, lycopene, and lutein content in tomatoes grown under continuous PAR spectrum LED lighting. Front Plant Sci. 2021;12:611236. [DOI] [PMC free article] [PubMed] [Google Scholar]
21.Chazaux M, Schiphorst C, Lazzari G, Caffarri S. Precise Estimation of chlorophyll a, b and carotenoid content by Deconvolution of the absorption spectrum and new simultaneous equations for Chl determination. Plant J. 2022;109(6):1630–48. [DOI] [PubMed] [Google Scholar]
22.Bradford MM. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976;72(1–2):248–54. [DOI] [PubMed] [Google Scholar]
23.Shi C-L, Sun N-H, Li H-a, Liu Q, Qi L. Effects of drying methods and storage on the composition and changes of soluble sugar components of Ipomoea batatas (L.) lam. 2022.
24.Żur I, Dubas E, Krzewska M, Waligórski P, Dziurka M, Janowiak F. Hormonal requirements for effective induction of microspore embryogenesis in triticale (× Triticosecale Wittm.) anther cultures. Plant Cell Rep. 2015;34:47–62. [DOI] [PMC free article] [PubMed] [Google Scholar]
25.Bremner J. Determination of nitrogen in soil by the Kjeldahl method. J Agricultural Sci. 1960;55(1):11–33. [Google Scholar]
26.Murphy J, Riley JP. A modified single solution method for the determination of phosphate in natural waters. Anal Chim Acta. 1962;27:31–6. [Google Scholar]
27.Szparaga A, Kocira S, Kocira A, Czerwińska E, Świeca M, Lorencowicz E, et al. Modification of growth, yield, and the nutraceutical and antioxidative potential of soybean through the use of synthetic biostimulants. Front Plant Sci. 2018;9:1401. [DOI] [PMC free article] [PubMed] [Google Scholar]
28.Rahman A, Harker T, Lewis W, Islam KR. Nano and chelated iron fertilization influences marketable yield, phytochemical properties, and antioxidant capacity of tomatoes. PLoS ONE. 2023;18(11):e0294033. [DOI] [PMC free article] [PubMed] [Google Scholar]
29.Hou D, Cui X, Liu M, Qie H, Tang Y, Xu R, et al. The effects of iron-based nanomaterials (Fe NMs) on plants under stressful environments: machine learning-assisted meta-analysis. J Environ Manage. 2024;354:120406. [DOI] [PubMed] [Google Scholar]
30.Mohamed AS, El-Sayed SM, Attia MS, El-Sayyad GS, Okla MK, Alwasel YA, et al. Potential impact of iron oxide conjugated nano-fertilizer on growth, flowering and isozyme expression in Gardenia jasminoides. Notulae Botanicae Horti Agrobotanici Cluj-Napoca. 2023;51(4):1–24. [Google Scholar]
31.Tombuloglu G, Tombuloglu H, Slimani Y, Almessiere MA, Baykal A, Bostancioglu SM, et al. Effects of foliar iron oxide nanoparticles (Fe3O4) application on photosynthetic parameters, distribution of mineral elements, magnetic behaviour, and photosynthetic genes in tomato (Solanum lycopersicum var. cerasiforme) plants. Plant Physiol Biochem. 2024;210:108616. [DOI] [PubMed] [Google Scholar]
32.Elbasuney S, El-Sayyad GS, Attia MS, Abdelaziz AM. Ferric oxide colloid: towards green nano-fertilizer for tomato plant with enhanced vegetative growth and immune response against fusarium wilt disease. J Inorg Organomet Polym Mater. 2022;32(11):4270–83. [DOI] [PMC free article] [PubMed] [Google Scholar]
33.El-Desouky HS, Islam KR, Bergefurd B, Gao G, Harker T, Abd-El-Dayem H, et al. Nano iron fertilization significantly increases tomato yield by increasing plants’ vegetable growth and photosynthetic efficiency. J Plant Nutr. 2021;44(11):1649–63. [Google Scholar]
34.Nazarideljou MJ, Rahmani S, Kalanaky S, Hojati M, Nazaran MH. Nanochelating-based fertilizers: innovations for yield enhancement in hydroponic cultivation. Sci Hort. 2024;326:112776. [Google Scholar]
35.Mostafavi S, Asadi-Gharneh HA, Tavallali V, Rowshan V. Phytochemical and growth impacts of silicon-DA6 and silicon-atonik nanocomplexes in Zataria multiflora and their potential as Si fertilizers. South Afr J Bot. 2024;172:242–53. [Google Scholar]
36.Djanaguiraman M, Sheeba JA, Devi DD, Bangarusamy U. Effect of Atonik seed treatment on seedling physiology of cotton and tomato. J Biol Sci. 2005;5(2):163–9. [Google Scholar]
37.Raiesi-Ardali T, Maˈmani L, Chorom M, Moezzi A. Improved iron use efficiency in tomato using organically coated iron oxide nanoparticles as efficient bioavailable Fe sources. Chem Biol Technol Agric. 2022;9(1):59. [Google Scholar]
38.Dola DB, Mannan MA, Sarker U, Mamun MAA, Islam T, Ercisli S, et al. Nano-iron oxide accelerates growth, yield, and quality of Glycine max seed in water deficits. Front Plant Sci. 2022;13:992535. [DOI] [PMC free article] [PubMed] [Google Scholar]
39.Karaikal SK. Characterizing the utility of Atonik on improving rice response. to Herbicides: University of Arkansas; 2023. [Google Scholar]
40.Li Y, Hu J, Wei H, Jeong BR. A long-day photoperiod and 6-benzyladenine promote runner formation through upregulation of soluble sugar content in strawberry. Int J Mol Sci. 2020;21(14):4917. [DOI] [PMC free article] [PubMed] [Google Scholar]
41.Lu Q, Xu Z, Zhang Q, Zhang Z, Zhang Y, Zhang T, et al. Foliar application of Fe-fulvic acid: A strategy to reduce heavy metal accumulation and enhance nutritional quality. Food Chemistry: X. 2024;24:101904. [DOI] [PMC free article] [PubMed] [Google Scholar]
42.Askary M, Amirjani MR, Saberi T. Comparison of the effects of nano-iron fertilizer with iron-chelate on growth parameters and some biochemical properties of Catharanthus roseus. J Plant Nutr. 2017;40(7):974–82. [Google Scholar]
43.He D, Kaleem Z, Ali S, Shahbaz H, Zhang K, Li J, et al. Impact of iron oxide nanoparticles on cadmium toxicity mitigation in Brassica napus. Plant Physiol Biochem. 2025;220:109500. [DOI] [PubMed] [Google Scholar]
44.Mughal UA, Farid M, Sarfraz W, Abdel-Maksoud MA, Malik A, Abbas M, et al. Enhancing phytoremediation in chamomile (Matricaria chamomilla L.) using moringa extract and zero-valent iron nanoparticles. South Afr J Bot. 2025;177:14–25. [Google Scholar]
45.Haroun SA, Shukry WM, Abbas MA, Mowafy AM. Growth and physiological responses of Solanum lycopersicum to Atonik and benzyl adenine under vernalized conditions. J Ecol Nat Environ. 2011;3(9):319–31. [Google Scholar]
46.Higuchi K, Saito A. Elucidation of efficient photosynthesis in plants with limited iron. Soil Sci Plant Nutr. 2022;68(5–6):505–13. [Google Scholar]
47.Magnabosco P, Masi A, Shukla R, Bansal V, Carletti P. Advancing the impact of plant biostimulants to sustainable agriculture through nanotechnologies. Chem Biol Technol Agric. 2023;10(1):117. [Google Scholar]
48.Martinez-Alonso A, Garcia-Ibañez P, Bárzana G, Carvajal M. Leaf gas exchange and growth responses of tomato plants to external flavonoids application as biostimulators under normal and salt-stressed conditions. Agronomy. 2022;12(12):3230. [Google Scholar]
49.Roque IA, Soares LAA, Lima GSd, Lopes IAP, Silva LdA, Fernandes PD. Biomass, gas exchange and production of Cherry tomato cultivated under saline water and nitrogen fertilization. Revista Caatinga. 2022;35(3):686–96. [Google Scholar]
50.Li B, Zhou W. Role of biostimulants in improving yield and seed quality of marketable crops. Biostimulants for Improving Reproductive Growth and Crop Yield: Elsevier; 2025. pp. 219– 37.
51.Bunce J. Changes in the responses of leaf gas exchange to temperature and photosynthesis model parameters in four C3 species in the field. Plants. 2025;14(4):550. [DOI] [PMC free article] [PubMed] [Google Scholar]
52.Zrar DB, Aziz BR, Kanimarani SMS, Ali. Influence of nitrophenolates on vegetative growth and reproductive components of two pea (Pisum sativum L.) cultivars. 2021.
53.Roemhild K, von Maltzahn F, Weiskirchen R, Knüchel R, von Stillfried S, Lammers T. Iron metabolism: pathophysiology and Pharmacology. Trends Pharmacol Sci. 2021;42(8):640–56. [DOI] [PMC free article] [PubMed] [Google Scholar]
54.Khan MA, editor. Halophyte seed germination: success and pitfalls. International symposium on optimum resource utilization in salt affected ecosystems in arid and semi arid regions; 2002: Desert research centre Reno.
55.Glozer K, Ferguson L. Pomegranate production in Afghanistan. UCDAVIS Coll Agricultural Environ Sci. 2008(s 32).
56.Jalali-Honarmand S, Rasaei A, Saeidi M, Ghobadi M-E, Khanizadeh S. The effects of foliar application of plant hormones at booting stage on wheat yield components. Thai J Agricultural Sci. 2015;48(1):35–8. [Google Scholar]
57.Ghafariyan MH, Malakouti MJ, Dadpour MR, Stroeve P, Mahmoudi M. Effects of magnetite nanoparticles on soybean chlorophyll. Environ Sci Technol. 2013;47(18):10645–52. [DOI] [PubMed] [Google Scholar]
58.Li J, Cao X, Jia X, Liu L, Cao H, Qin W, et al. Iron deficiency leads to chlorosis through impacting chlorophyll synthesis and nitrogen metabolism in Areca catechu L. Front Plant Sci. 2021;12:710093. [DOI] [PMC free article] [PubMed] [Google Scholar]
59.Gao D, Ran C, Zhang Y, Wang X, Lu S, Geng Y, et al. Effect of different concentrations of foliar iron fertilizer on chlorophyll fluorescence characteristics of iron-deficient rice seedlings under saline sodic conditions. Plant Physiol Biochem. 2022;185:112–22. [DOI] [PubMed] [Google Scholar]
60.Wang Y, Wang S, Xu M, Xiao L, Dai Z, Li J. The impacts of γ-Fe2O3 and Fe3O4 nanoparticles on the physiology and fruit quality of muskmelon (Cucumis melo) plants. Environ Pollut. 2019;249:1011–8. [DOI] [PubMed] [Google Scholar]
61.Iwaniuk P, Łuniewski S, Kaczyński P, Łozowicka B. The influence of humic acids and nitrophenols on metabolic compounds and pesticide behavior in wheat under biotic stress. Agronomy. 2023;13(5):1378. [Google Scholar]
62.Niewęgłowski M, Sikorska A, Gugała M, Krasnodębska E, Zarzecka K. The effect of nitrogen fertilization and the use of biostimulators on the chemical composition of grains of two varieties of corn (Zea mays L). PLoS ONE. 2024;19(12):e0311560. [DOI] [PMC free article] [PubMed] [Google Scholar]
63.Mahmoud AWM, Ayad AA, Abdel-Aziz HS, Williams LL, El-Shazoly RM, Abdel-Wahab A, et al. Foliar application of different iron sources improves morpho-physiological traits and nutritional quality of broad bean grown in sandy soil. Plants. 2022;11(19):2599. [DOI] [PMC free article] [PubMed] [Google Scholar]
64.Zodape S, Mukhopadhyay S, Eswaran K, Reddy M, Chikara J. Enhanced yield and nutritional quality in green gram (Phaseolus radiata L) treated with seaweed (Kappaphycus alvarezii) extract. 2010.
65.Sabagh EL, Islam A, Hossain MS, Iqbal A, Mubeen MA, Waleed M. Phytohormones as growth regulators during abiotic stress tolerance in plants. Front Agron. 2022;4:765068. [Google Scholar]
66.Müller M, Munné-Bosch S. Hormonal impact on photosynthesis and photoprotection in plants. Plant Physiol. 2021;185(4):1500–22. [DOI] [PMC free article] [PubMed] [Google Scholar]
67.Sah SK, Reddy KR, Li J. Abscisic acid and abiotic stress tolerance in crop plants. Front Plant Sci. 2016;7:571. [DOI] [PMC free article] [PubMed] [Google Scholar]
68.Raza A, Salehi H, Rahman MA, Zahid Z, Madadkar Haghjou M, Najafi-Kakavand S, et al. Plant hormones and neurotransmitter interactions mediate antioxidant defenses under induced oxidative stress in plants. Front Plant Sci. 2022;13:961872. [DOI] [PMC free article] [PubMed] [Google Scholar]
69.Wu R, Chen J, Lin Y, Jia Q, Guo Y, Liu J, et al. Genome-wide identification, expression analysis, and potential roles under abiotic stress of the YUCCA gene family in Mungbean (Vigna radiata L). Int J Mol Sci. 2023;24(2):1603. [DOI] [PMC free article] [PubMed] [Google Scholar]
70.Bindraban PS, Dimkpa C, Nagarajan L, Roy A, Rabbinge R. Revisiting fertilisers and fertilisation strategies for improved nutrient uptake by plants. Biol Fertil Soils. 2015;51(8):897–911. [Google Scholar]
71.Yang D, Zhao F, Zhu D, Chen X, Kong X, Wu Y, et al. Progressive chromatin Silencing of ABA biosynthesis genes permits seed germination in Arabidopsis. Plant Cell. 2022;34(8):2871–91. [DOI] [PMC free article] [PubMed] [Google Scholar]
72.Abd Alla MA, El-Greadly NH, Emam Y. Effect of foliar spray with biostimulants on growth, head yield, phytohormones and nutrients of cabbage (Brassica Oleracea var. capitata). Egypt J Hort. 2015;42(2):707–19. [Google Scholar]
73.Frigerio M, Alabadí D, Pérez-Gómez J, García-Cárcel L, Phillips AL, Hedden P, et al. Transcriptional regulation of Gibberellin metabolism genes by auxin signaling in Arabidopsis. Plant Physiol. 2006;142(2):553–63. [DOI] [PMC free article] [PubMed] [Google Scholar]
74.Pezzani R, Salehi B, Vitalini S, Iriti M, Zuñiga FA, Sharifi-Rad J, et al. Synergistic effects of plant derivatives and conventional chemotherapeutic agents: an update on the cancer perspective. Medicina. 2019;55(4):110. [DOI] [PMC free article] [PubMed] [Google Scholar]
75.El-Shabrawy R. Effect of seed soaking and/or foliar spray of Atonik on vegetative growth, sex expression and yield of squash plants. J Plant Prod. 2009;34(2):1101–6. [Google Scholar]
76.Das P, Nutan KK, Singla-Pareek SL, Pareek A. Understanding salinity responses and adopting ‘omics-based’approaches to generate salinity tolerant cultivars of rice. Front Plant Sci. 2015;6:712. [DOI] [PMC free article] [PubMed] [Google Scholar]
77.Karimi S, Tavallali V, Ferguson L, Mirzaei S. Developing a nano-Fe complex to supply iron and improve salinity tolerance of pistachio under calcium bicarbonate stress. Commun Soil Sci Plant Anal. 2020;51(14):1835–51. [Google Scholar]
78.Avci H, Yaman M. Concentrations, accumulation, and interactions of redoximorphic metals (Fe, Mn) between other elements in plants grown on wastewater-irrigated and control soils. Water Air Soil Pollut. 2014;225:1–16. [Google Scholar]
79.Wang Q, Chen M, Hao Q, Zeng H, He Y. Research and progress on the mechanism of iron transfer and accumulation in rice grains. Plants. 2021;10(12):2610. [DOI] [PMC free article] [PubMed] [Google Scholar]
80.Koleva L, Umar A, Yasin NA, Shah AA, Siddiqui MH, Alamri S, et al. Iron oxide and silicon nanoparticles modulate mineral nutrient homeostasis and metabolism in cadmium-stressed Phaseolus vulgaris. Front Plant Sci. 2022;13:806781. [DOI] [PMC free article] [PubMed] [Google Scholar]
81.Sabet H, Mortazaeinezhad F. Yield, growth and Fe uptake of Cumin (Cuminum cyminum L.) affected by Fe-nano, Fe-chelated and Fe-siderophore fertilization in the calcareous soils. J Trace Elem Med Biol. 2018;50:154–60. [DOI] [PubMed] [Google Scholar]
82.Shafiq F, Ahmad A, Anwar S, Nisa M-u, Iqbal M, Raza SH, et al. Spinel nanocomposite (nMnZnFe2O4) synchronously promotes grain yield and Fe–Zn biofortification in non-aromatic rice. Plant Physiol Biochem. 2023;201:107830. [DOI] [PubMed] [Google Scholar]
83.Ahmad S, Ahmad N, Islam MS, Ahmad MA, Ercisli S, Ullah R, et al. Rice seeds biofortification using biogenic Iron oxide nanoparticles synthesized by using Glycyrrhiza glabra: a study on growth and yield ımprovement. Sci Rep. 2024;14(1):12368. [DOI] [PMC free article] [PubMed] [Google Scholar]
84.Wang B, Zhu X, Guo X, Qi X, Feng F, Zhang Y, et al. Nitrate modulates lateral root formation by regulating the auxin response and transport in rice. Genes. 2021;12(6):850. [DOI] [PMC free article] [PubMed] [Google Scholar]
85.Guerinot ML. The ZIP family of metal transporters. Biochim Et Biophys Acta (BBA)-Biomembranes. 2000;1465(1–2):190–8. [DOI] [PubMed] [Google Scholar]
86.Ashraf M, Foolad MR. Roles of glycine betaine and proline in improving plant abiotic stress resistance. Environ Exp Bot. 2007;59(2):206–16. [Google Scholar]
87.Murtaza G, Ahmed Z, Usman M, Tariq W, Ullah Z, Shareef M, et al. Biochar induced modifications in soil properties and its impacts on crop growth and production. J Plant Nutr. 2021;44(11):1677–91. [Google Scholar]
88.Djanaguiraman M, Pandiyan M, Devi DD. Abscission of tomato fruit follows oxidative damage and its manipulation by Atonik spray. Int J Agr Biol. 2005;7(1):39–44.

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

The data presented in this study are available on request from the authors.

[CR1] 1.Hell R, Stephan UW. Iron uptake, trafficking and homeostasis in plants. Planta. 2003;216:541–51. [DOI] [PubMed] [Google Scholar]

[CR2] 2.Sharma P, Holliger N, Pfromm PH, Liu B, Chikan V. Size-controlled synthesis of iron and iron oxide nanoparticles by the rapid inductive heating method. ACS Omega. 2020;5(31):19853–60. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR3] 3.Yang Y, Huang M, Qian J, Gao D, Liang X. Tunable Fe3O4 nanorods for enhanced magnetic hyperthermia performance. Sci Rep. 2020;10(1):8331. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR4] 4.Kornarzyński K, Sujak A, Czernel G, Wiącek D. Effect of Fe3O4 nanoparticles on germination of seeds and concentration of elements in Helianthus annuus L. under constant magnetic field. Sci Rep. 2020;10(1):8068. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR5] 5.Yoon HY, Lee JG, Esposti LD, Iafisco M, Kim PJ, Shin SG, et al. Synergistic release of crop nutrients and stimulants from hydroxyapatite nanoparticles functionalized with humic substances: toward a multifunctional nanofertilizer. ACS Omega. 2020;5(12):6598–610. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR6] 6.Zia-ur-Rehman M, Naeem A, Khalid H, Rizwan M, Ali S, Azhar M. Responses of plants to iron oxide nanoparticles. Nanomaterials in plants, algae, and microorganisms. Elsevier; 2018. pp. 221–38.

[CR7] 7.Kumar R, Ashfaq M, Verma N. Synthesis of novel PVA–starch formulation-supported Cu–Zn nanoparticle carrying carbon nanofibers as a nanofertilizer: controlled release of micronutrients. J Mater Sci. 2018;53(10):7150–64. [Google Scholar]

[CR8] 8.Kulikova NA, Polyakov AY, Lebedev VA, Abroskin DP, Volkov DS, Pankratov DA, et al. Key roles of size and crystallinity of nanosized iron Hydr (oxides) stabilized by humic substances in iron bioavailability to plants. J Agric Food Chem. 2017;65(51):11157–69. [DOI] [PubMed] [Google Scholar]

[CR9] 9.Li J, Hu J, Xiao L, Wang Y, Wang X. Interaction mechanisms between α-Fe2O3, γ-Fe2O3 and Fe3O4 nanoparticles and Citrus maxima seedlings. Sci Total Environ. 2018;625:677–85. [DOI] [PubMed] [Google Scholar]

[CR10] 10.Peng L, Qin P, Lei M, Zeng Q, Song H, Yang J, et al. Modifying Fe3O4 nanoparticles with humic acid for removal of Rhodamine B in water. J Hazard Mater. 2012;209:193–8. [DOI] [PubMed] [Google Scholar]

[CR11] 11.Means JL, Crerar DA, Duguid JO. Migration of radioactive wastes: radionuclide mobilization by complexing agents. Science. 1978;200(4349):1477–81. [DOI] [PubMed] [Google Scholar]

[CR12] 12.Tavallali V, Rahmati S, Bahmanzadegan A, Lasibi MJM. Variation in developmental and phytochemical characteristics of Calendula officinalis L. using foliar application of iron nanoparticles formed on hyaluronic acid. Sci Hort. 2024;323:112539. [Google Scholar]

[CR13] 13.Kocira A, Kocira S, Świeca M, Złotek U, Jakubczyk A, Kapela K. Effect of foliar application of a nitrophenolate–based biostimulant on the yield and quality of two bean cultivars. Sci Hort. 2017;214:76–82. [Google Scholar]

[CR14] 14.Przybysz A, Wrochna M, Slowinski A, Gawronska H. Stimulatory effect of Asahi SL on selected plant species. Acta Scientiarum Polonorum Hortorum Cultus. 2010;9(2):53–64.

[CR15] 15.Batool Z, Ishfaq M, Akbar N, Zulfiqar U, Anjum SA, Shafiq M, et al. Exogenous application of Atonik (sodium nitrophenolate) under skip irrigation regimes modulated the physiology, growth and productivity of Zea mays L. Arch Agron Soil Sci. 2023;69(12):2325–39. [Google Scholar]

[CR16] 16.Djanaguiraman M, Sheeba JA, Devi DD, Bangarusamy U. Response of cotton to Atonik and TIBA for growth, enzymes and yield. J Biol Sci. 2005;5(2):158–62. [Google Scholar]

[CR17] 17.Przybysz A, Gawrońska H, Gajc-Wolska J. Biological mode of action of a nitrophenolates-based biostimulant: case study. Front Plant Sci. 2014;5:713. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR18] 18.Gulluoglu L, Arİoglu H, Arslan M. Effects of some plant growth regulators and nutrient complexes on above-ground biomass and seed yield of soybean grown under heat-stressed environment. 2006.

[CR19] 19.Zhang Y, Liang Y, Han J, Hu X, Li X, Zhao H, et al. Interactive effects of iron and photoperiods on tomato plant growth and fruit quality. J Plant Growth Regul. 2023;42(1):376–89. [Google Scholar]

[CR20] 20.Dannehl D, Schwend T, Veit D, Schmidt U. Increase of yield, lycopene, and lutein content in tomatoes grown under continuous PAR spectrum LED lighting. Front Plant Sci. 2021;12:611236. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR21] 21.Chazaux M, Schiphorst C, Lazzari G, Caffarri S. Precise Estimation of chlorophyll a, b and carotenoid content by Deconvolution of the absorption spectrum and new simultaneous equations for Chl determination. Plant J. 2022;109(6):1630–48. [DOI] [PubMed] [Google Scholar]

[CR22] 22.Bradford MM. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976;72(1–2):248–54. [DOI] [PubMed] [Google Scholar]

[CR23] 23.Shi C-L, Sun N-H, Li H-a, Liu Q, Qi L. Effects of drying methods and storage on the composition and changes of soluble sugar components of Ipomoea batatas (L.) lam. 2022.

[CR24] 24.Żur I, Dubas E, Krzewska M, Waligórski P, Dziurka M, Janowiak F. Hormonal requirements for effective induction of microspore embryogenesis in triticale (× Triticosecale Wittm.) anther cultures. Plant Cell Rep. 2015;34:47–62. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR25] 25.Bremner J. Determination of nitrogen in soil by the Kjeldahl method. J Agricultural Sci. 1960;55(1):11–33. [Google Scholar]

[CR26] 26.Murphy J, Riley JP. A modified single solution method for the determination of phosphate in natural waters. Anal Chim Acta. 1962;27:31–6. [Google Scholar]

[CR27] 27.Szparaga A, Kocira S, Kocira A, Czerwińska E, Świeca M, Lorencowicz E, et al. Modification of growth, yield, and the nutraceutical and antioxidative potential of soybean through the use of synthetic biostimulants. Front Plant Sci. 2018;9:1401. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR28] 28.Rahman A, Harker T, Lewis W, Islam KR. Nano and chelated iron fertilization influences marketable yield, phytochemical properties, and antioxidant capacity of tomatoes. PLoS ONE. 2023;18(11):e0294033. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR29] 29.Hou D, Cui X, Liu M, Qie H, Tang Y, Xu R, et al. The effects of iron-based nanomaterials (Fe NMs) on plants under stressful environments: machine learning-assisted meta-analysis. J Environ Manage. 2024;354:120406. [DOI] [PubMed] [Google Scholar]

[CR30] 30.Mohamed AS, El-Sayed SM, Attia MS, El-Sayyad GS, Okla MK, Alwasel YA, et al. Potential impact of iron oxide conjugated nano-fertilizer on growth, flowering and isozyme expression in Gardenia jasminoides. Notulae Botanicae Horti Agrobotanici Cluj-Napoca. 2023;51(4):1–24. [Google Scholar]

[CR31] 31.Tombuloglu G, Tombuloglu H, Slimani Y, Almessiere MA, Baykal A, Bostancioglu SM, et al. Effects of foliar iron oxide nanoparticles (Fe3O4) application on photosynthetic parameters, distribution of mineral elements, magnetic behaviour, and photosynthetic genes in tomato (Solanum lycopersicum var. cerasiforme) plants. Plant Physiol Biochem. 2024;210:108616. [DOI] [PubMed] [Google Scholar]

[CR32] 32.Elbasuney S, El-Sayyad GS, Attia MS, Abdelaziz AM. Ferric oxide colloid: towards green nano-fertilizer for tomato plant with enhanced vegetative growth and immune response against fusarium wilt disease. J Inorg Organomet Polym Mater. 2022;32(11):4270–83. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR33] 33.El-Desouky HS, Islam KR, Bergefurd B, Gao G, Harker T, Abd-El-Dayem H, et al. Nano iron fertilization significantly increases tomato yield by increasing plants’ vegetable growth and photosynthetic efficiency. J Plant Nutr. 2021;44(11):1649–63. [Google Scholar]

[CR34] 34.Nazarideljou MJ, Rahmani S, Kalanaky S, Hojati M, Nazaran MH. Nanochelating-based fertilizers: innovations for yield enhancement in hydroponic cultivation. Sci Hort. 2024;326:112776. [Google Scholar]

[CR35] 35.Mostafavi S, Asadi-Gharneh HA, Tavallali V, Rowshan V. Phytochemical and growth impacts of silicon-DA6 and silicon-atonik nanocomplexes in Zataria multiflora and their potential as Si fertilizers. South Afr J Bot. 2024;172:242–53. [Google Scholar]

[CR36] 36.Djanaguiraman M, Sheeba JA, Devi DD, Bangarusamy U. Effect of Atonik seed treatment on seedling physiology of cotton and tomato. J Biol Sci. 2005;5(2):163–9. [Google Scholar]

[CR37] 37.Raiesi-Ardali T, Maˈmani L, Chorom M, Moezzi A. Improved iron use efficiency in tomato using organically coated iron oxide nanoparticles as efficient bioavailable Fe sources. Chem Biol Technol Agric. 2022;9(1):59. [Google Scholar]

[CR38] 38.Dola DB, Mannan MA, Sarker U, Mamun MAA, Islam T, Ercisli S, et al. Nano-iron oxide accelerates growth, yield, and quality of Glycine max seed in water deficits. Front Plant Sci. 2022;13:992535. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR39] 39.Karaikal SK. Characterizing the utility of Atonik on improving rice response. to Herbicides: University of Arkansas; 2023. [Google Scholar]

[CR40] 40.Li Y, Hu J, Wei H, Jeong BR. A long-day photoperiod and 6-benzyladenine promote runner formation through upregulation of soluble sugar content in strawberry. Int J Mol Sci. 2020;21(14):4917. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR41] 41.Lu Q, Xu Z, Zhang Q, Zhang Z, Zhang Y, Zhang T, et al. Foliar application of Fe-fulvic acid: A strategy to reduce heavy metal accumulation and enhance nutritional quality. Food Chemistry: X. 2024;24:101904. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR42] 42.Askary M, Amirjani MR, Saberi T. Comparison of the effects of nano-iron fertilizer with iron-chelate on growth parameters and some biochemical properties of Catharanthus roseus. J Plant Nutr. 2017;40(7):974–82. [Google Scholar]

[CR43] 43.He D, Kaleem Z, Ali S, Shahbaz H, Zhang K, Li J, et al. Impact of iron oxide nanoparticles on cadmium toxicity mitigation in Brassica napus. Plant Physiol Biochem. 2025;220:109500. [DOI] [PubMed] [Google Scholar]

[CR44] 44.Mughal UA, Farid M, Sarfraz W, Abdel-Maksoud MA, Malik A, Abbas M, et al. Enhancing phytoremediation in chamomile (Matricaria chamomilla L.) using moringa extract and zero-valent iron nanoparticles. South Afr J Bot. 2025;177:14–25. [Google Scholar]

[CR45] 45.Haroun SA, Shukry WM, Abbas MA, Mowafy AM. Growth and physiological responses of Solanum lycopersicum to Atonik and benzyl adenine under vernalized conditions. J Ecol Nat Environ. 2011;3(9):319–31. [Google Scholar]

[CR46] 46.Higuchi K, Saito A. Elucidation of efficient photosynthesis in plants with limited iron. Soil Sci Plant Nutr. 2022;68(5–6):505–13. [Google Scholar]

[CR47] 47.Magnabosco P, Masi A, Shukla R, Bansal V, Carletti P. Advancing the impact of plant biostimulants to sustainable agriculture through nanotechnologies. Chem Biol Technol Agric. 2023;10(1):117. [Google Scholar]

[CR48] 48.Martinez-Alonso A, Garcia-Ibañez P, Bárzana G, Carvajal M. Leaf gas exchange and growth responses of tomato plants to external flavonoids application as biostimulators under normal and salt-stressed conditions. Agronomy. 2022;12(12):3230. [Google Scholar]

[CR49] 49.Roque IA, Soares LAA, Lima GSd, Lopes IAP, Silva LdA, Fernandes PD. Biomass, gas exchange and production of Cherry tomato cultivated under saline water and nitrogen fertilization. Revista Caatinga. 2022;35(3):686–96. [Google Scholar]

[CR50] 50.Li B, Zhou W. Role of biostimulants in improving yield and seed quality of marketable crops. Biostimulants for Improving Reproductive Growth and Crop Yield: Elsevier; 2025. pp. 219– 37.

[CR51] 51.Bunce J. Changes in the responses of leaf gas exchange to temperature and photosynthesis model parameters in four C3 species in the field. Plants. 2025;14(4):550. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR52] 52.Zrar DB, Aziz BR, Kanimarani SMS, Ali. Influence of nitrophenolates on vegetative growth and reproductive components of two pea (Pisum sativum L.) cultivars. 2021.

[CR53] 53.Roemhild K, von Maltzahn F, Weiskirchen R, Knüchel R, von Stillfried S, Lammers T. Iron metabolism: pathophysiology and Pharmacology. Trends Pharmacol Sci. 2021;42(8):640–56. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR54] 54.Khan MA, editor. Halophyte seed germination: success and pitfalls. International symposium on optimum resource utilization in salt affected ecosystems in arid and semi arid regions; 2002: Desert research centre Reno.

[CR55] 55.Glozer K, Ferguson L. Pomegranate production in Afghanistan. UCDAVIS Coll Agricultural Environ Sci. 2008(s 32).

[CR56] 56.Jalali-Honarmand S, Rasaei A, Saeidi M, Ghobadi M-E, Khanizadeh S. The effects of foliar application of plant hormones at booting stage on wheat yield components. Thai J Agricultural Sci. 2015;48(1):35–8. [Google Scholar]

[CR57] 57.Ghafariyan MH, Malakouti MJ, Dadpour MR, Stroeve P, Mahmoudi M. Effects of magnetite nanoparticles on soybean chlorophyll. Environ Sci Technol. 2013;47(18):10645–52. [DOI] [PubMed] [Google Scholar]

[CR58] 58.Li J, Cao X, Jia X, Liu L, Cao H, Qin W, et al. Iron deficiency leads to chlorosis through impacting chlorophyll synthesis and nitrogen metabolism in Areca catechu L. Front Plant Sci. 2021;12:710093. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR59] 59.Gao D, Ran C, Zhang Y, Wang X, Lu S, Geng Y, et al. Effect of different concentrations of foliar iron fertilizer on chlorophyll fluorescence characteristics of iron-deficient rice seedlings under saline sodic conditions. Plant Physiol Biochem. 2022;185:112–22. [DOI] [PubMed] [Google Scholar]

[CR60] 60.Wang Y, Wang S, Xu M, Xiao L, Dai Z, Li J. The impacts of γ-Fe2O3 and Fe3O4 nanoparticles on the physiology and fruit quality of muskmelon (Cucumis melo) plants. Environ Pollut. 2019;249:1011–8. [DOI] [PubMed] [Google Scholar]

[CR61] 61.Iwaniuk P, Łuniewski S, Kaczyński P, Łozowicka B. The influence of humic acids and nitrophenols on metabolic compounds and pesticide behavior in wheat under biotic stress. Agronomy. 2023;13(5):1378. [Google Scholar]

[CR62] 62.Niewęgłowski M, Sikorska A, Gugała M, Krasnodębska E, Zarzecka K. The effect of nitrogen fertilization and the use of biostimulators on the chemical composition of grains of two varieties of corn (Zea mays L). PLoS ONE. 2024;19(12):e0311560. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR63] 63.Mahmoud AWM, Ayad AA, Abdel-Aziz HS, Williams LL, El-Shazoly RM, Abdel-Wahab A, et al. Foliar application of different iron sources improves morpho-physiological traits and nutritional quality of broad bean grown in sandy soil. Plants. 2022;11(19):2599. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR64] 64.Zodape S, Mukhopadhyay S, Eswaran K, Reddy M, Chikara J. Enhanced yield and nutritional quality in green gram (Phaseolus radiata L) treated with seaweed (Kappaphycus alvarezii) extract. 2010.

[CR65] 65.Sabagh EL, Islam A, Hossain MS, Iqbal A, Mubeen MA, Waleed M. Phytohormones as growth regulators during abiotic stress tolerance in plants. Front Agron. 2022;4:765068. [Google Scholar]

[CR66] 66.Müller M, Munné-Bosch S. Hormonal impact on photosynthesis and photoprotection in plants. Plant Physiol. 2021;185(4):1500–22. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR67] 67.Sah SK, Reddy KR, Li J. Abscisic acid and abiotic stress tolerance in crop plants. Front Plant Sci. 2016;7:571. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR68] 68.Raza A, Salehi H, Rahman MA, Zahid Z, Madadkar Haghjou M, Najafi-Kakavand S, et al. Plant hormones and neurotransmitter interactions mediate antioxidant defenses under induced oxidative stress in plants. Front Plant Sci. 2022;13:961872. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR69] 69.Wu R, Chen J, Lin Y, Jia Q, Guo Y, Liu J, et al. Genome-wide identification, expression analysis, and potential roles under abiotic stress of the YUCCA gene family in Mungbean (Vigna radiata L). Int J Mol Sci. 2023;24(2):1603. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR70] 70.Bindraban PS, Dimkpa C, Nagarajan L, Roy A, Rabbinge R. Revisiting fertilisers and fertilisation strategies for improved nutrient uptake by plants. Biol Fertil Soils. 2015;51(8):897–911. [Google Scholar]

[CR71] 71.Yang D, Zhao F, Zhu D, Chen X, Kong X, Wu Y, et al. Progressive chromatin Silencing of ABA biosynthesis genes permits seed germination in Arabidopsis. Plant Cell. 2022;34(8):2871–91. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR72] 72.Abd Alla MA, El-Greadly NH, Emam Y. Effect of foliar spray with biostimulants on growth, head yield, phytohormones and nutrients of cabbage (Brassica Oleracea var. capitata). Egypt J Hort. 2015;42(2):707–19. [Google Scholar]

[CR73] 73.Frigerio M, Alabadí D, Pérez-Gómez J, García-Cárcel L, Phillips AL, Hedden P, et al. Transcriptional regulation of Gibberellin metabolism genes by auxin signaling in Arabidopsis. Plant Physiol. 2006;142(2):553–63. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR74] 74.Pezzani R, Salehi B, Vitalini S, Iriti M, Zuñiga FA, Sharifi-Rad J, et al. Synergistic effects of plant derivatives and conventional chemotherapeutic agents: an update on the cancer perspective. Medicina. 2019;55(4):110. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR75] 75.El-Shabrawy R. Effect of seed soaking and/or foliar spray of Atonik on vegetative growth, sex expression and yield of squash plants. J Plant Prod. 2009;34(2):1101–6. [Google Scholar]

[CR76] 76.Das P, Nutan KK, Singla-Pareek SL, Pareek A. Understanding salinity responses and adopting ‘omics-based’approaches to generate salinity tolerant cultivars of rice. Front Plant Sci. 2015;6:712. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR77] 77.Karimi S, Tavallali V, Ferguson L, Mirzaei S. Developing a nano-Fe complex to supply iron and improve salinity tolerance of pistachio under calcium bicarbonate stress. Commun Soil Sci Plant Anal. 2020;51(14):1835–51. [Google Scholar]

[CR78] 78.Avci H, Yaman M. Concentrations, accumulation, and interactions of redoximorphic metals (Fe, Mn) between other elements in plants grown on wastewater-irrigated and control soils. Water Air Soil Pollut. 2014;225:1–16. [Google Scholar]

[CR79] 79.Wang Q, Chen M, Hao Q, Zeng H, He Y. Research and progress on the mechanism of iron transfer and accumulation in rice grains. Plants. 2021;10(12):2610. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR80] 80.Koleva L, Umar A, Yasin NA, Shah AA, Siddiqui MH, Alamri S, et al. Iron oxide and silicon nanoparticles modulate mineral nutrient homeostasis and metabolism in cadmium-stressed Phaseolus vulgaris. Front Plant Sci. 2022;13:806781. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR81] 81.Sabet H, Mortazaeinezhad F. Yield, growth and Fe uptake of Cumin (Cuminum cyminum L.) affected by Fe-nano, Fe-chelated and Fe-siderophore fertilization in the calcareous soils. J Trace Elem Med Biol. 2018;50:154–60. [DOI] [PubMed] [Google Scholar]

[CR82] 82.Shafiq F, Ahmad A, Anwar S, Nisa M-u, Iqbal M, Raza SH, et al. Spinel nanocomposite (nMnZnFe2O4) synchronously promotes grain yield and Fe–Zn biofortification in non-aromatic rice. Plant Physiol Biochem. 2023;201:107830. [DOI] [PubMed] [Google Scholar]

[CR83] 83.Ahmad S, Ahmad N, Islam MS, Ahmad MA, Ercisli S, Ullah R, et al. Rice seeds biofortification using biogenic Iron oxide nanoparticles synthesized by using Glycyrrhiza glabra: a study on growth and yield ımprovement. Sci Rep. 2024;14(1):12368. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR84] 84.Wang B, Zhu X, Guo X, Qi X, Feng F, Zhang Y, et al. Nitrate modulates lateral root formation by regulating the auxin response and transport in rice. Genes. 2021;12(6):850. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CR85] 85.Guerinot ML. The ZIP family of metal transporters. Biochim Et Biophys Acta (BBA)-Biomembranes. 2000;1465(1–2):190–8. [DOI] [PubMed] [Google Scholar]

[CR86] 86.Ashraf M, Foolad MR. Roles of glycine betaine and proline in improving plant abiotic stress resistance. Environ Exp Bot. 2007;59(2):206–16. [Google Scholar]

[CR87] 87.Murtaza G, Ahmed Z, Usman M, Tariq W, Ullah Z, Shareef M, et al. Biochar induced modifications in soil properties and its impacts on crop growth and production. J Plant Nutr. 2021;44(11):1677–91. [Google Scholar]

[CR88] 88.Djanaguiraman M, Pandiyan M, Devi DD. Abscission of tomato fruit follows oxidative damage and its manipulation by Atonik spray. Int J Agr Biol. 2005;7(1):39–44.

PERMALINK

Synergistic effects of Fe nanocomplex and nitrophenolate-based biostimulant on growth and physiological performance of tomato seedlings

Vahid Tavallali

Mina Dashti Darvishzadeh

Abstract

Introduction

Materials and methods

Preparation of iron nanocomplex

Fig. 1.

Planting tomatoes in the greenhouse

Table 1.

Plant growth measurement

Chlorophyll and soluble protein content assay

Chlorophyll content

Soluble protein content

Measurement of soluble sugar

Analysis of plant hormone levels

Measurement of mineral elements

Statistical analysis

Results and discussion

Growth characteristics

Table 2.

Fig. 2.

Fig. 3.

Leaf gas exchange parameters

Table 3.

Fig. 4.

Chlorophyll, soluble protein and soluble sugar content

Table 4.

Table 5.

Fig. 5.

Plant hormone levels and mineral elements

Table 6.

Fig. 6.

Fig. 7.

Fig. 8.

Conclusions

Acknowledgements

Abbreviations

Authors’ contributions

Funding

Data availability

Declarations

Ethics approval and consent to participate

Consent for publication

Competing interests

Footnotes

References

Associated Data

Data Availability Statement

ACTIONS

PERMALINK

RESOURCES

Similar articles

Cited by other articles

Links to NCBI Databases