Revista Mexicana de Ciencias Agrícolas   special publication number 28   September 15 - October 30, 2022

DOI: https://doi.org/10.29312/remexca.v13i28.3272

Article

Effect of nano-biofortification with iron on yield and bioactive
compounds in cucumber

Reyna Roxana Guillén-Enríquez1

Lamberto Zuñiga-Estrada2

Damaris Leopoldina Ojeda-Barrios3

Tomas Rivas-García4

Redamés Trejo-Valencia5

Pablo Preciado-Rangel1§

1National Technological Institute of Mexico-Campus Technological Institute of Torreón. Old Highway Torreón-San Pedro km 7.5, Torreón, Coahuila, Mexico. (reguillen@outlook.com).

2The Huastecas Experimental Field-INIFAP. Tampico-Mante highway km 55, Villa Cuauhtémoc, Tamaulipas, Mexico. ZC. 89610. (lzunigae@hotmail.com).

3Faculty of Agrotechnological Sciences-Autonomous University of Chihuahua-University Campus I. Chihuahua, Mexico. ZC. 31350. (dojeda@uach.mx).

 4CONACYT-Chapingo Autonomous University. Mexico-Texcoco Federal Highway km 38.5, Chapingo, Texcoco, Mexico. ZC. 56230. (tomas.rivas@conacyt.mx).

 5National Technological Institute of Mexico-Campus Technological Institute of Minatitlán. Blvd. Technological Institutes S/N, col. Buena Vista Norte, Minatitlán, Veracruz, Mexico. ZC. 96848. (radamestv@hotmail.com).

§Corresponding author: ppreciador@yahoo.com.mx.

Abstract

Iron (Fe) is an indispensable micronutrient for living beings. However, and despite the fact that it is one of the most abundant metals in the earth’s crust, there is low availability for crops, causing a deficit in the diet of around two million people in the world. Nano-biofortification can mitigate this deficiency since its application in crops improves the biosynthesis of bioactive compounds and promotes their bioaccumulation. The objective of this research was to evaluate the effect of foliar application of Fe nanoparticles (Fe2O3 NPs) on the yield and biosynthesis of bioactive compounds in cucumber fruits. Four treatments were applied via foliar: 0, 50, 75 and 100 mg L-1 of Fe2O3 NPs. Foliar spraying with Fe2O3 NPs improved the yield and biosynthesis of bioactive compounds in cucumber fruits, increasing the yield by 38.99%, the biosynthesis of compounds by 30.18% and an increase of 23.26% of Fe in fruits. Foliar spraying of Fe2O3 NPs is an alternative to increase agricultural production, decreasing Fe deficiency, while improving the biosynthesis of bioactive compounds in order to ensure food and nutrition security.

Keywords: Cucumis sativus L, bioactive compounds, nanoparticles.

Reception date: June 2022

Acceptance date: August 2022

Introduction

Iron (Fe) is an indispensable micronutrient for living beings; in plants it participates in photosynthesis, respiration, enzymatic processes, conversion of the oxidation state, cell cycle, oxygen transport and storage, synthesis of hormones and DNA (Zhou and Tan, 2017). Although high concentrations of Fe are found in the earth’s crust, there are deficiencies of this element in crops since it is not always in forms available to plants (Konate et al., 2018).

This causes that plant-based foods have low concentration of this trace element, generating health problems to two million people in the world, with anemia being the main nutritional pathology (43% children, 40% pregnant women and 33% non-pregnant women) (Lowry et al., 2019). The daily intake to prevent Fe deficiency is 0.27 to 10 mg day-1 for children and 11 to 27 mg day-1 for adults (Abbasifar et al., 2020). The alternatives used to mitigate this situation include the use of Fe supplements and fortified products, which have failed to reduce the deficit of this trace element, mainly due to the cost of the products (Tripathi and Mishra, 2020).

The use of metal nanoparticles has shown increases in germination, resistance to stress, increased absorption of nutrients and plant growth (Yusefi-Tanha et al., 2020). In addition, they reduce soil pollution and degradation caused by the excessive use of chemical fertilizers (Wang et al., 2018). Fe nanoparticles (Fe NPs) can increase crop production and quality (Hu et al., 2017) as they are highly effective when sprayed on plants, thus reducing the impact of chemicals on the environment (Sega et al., 2019).

Rui et al. (2016) states that Fe NPs can replace Fe fertilizers in Arachis hypogaea plants. Several studies show that iron oxide NPs (Fe2O3 NPs) increase biomass and yield up to 48% in Glycine max plants (Sheykhbaglou et al., 2010). As well as sugars, proteins and chlorophyll in Cucumis melo L (Wang et al., 2016); they also increase the level of phytohormones in Oryza sativa (Li et al., 2021). Some studies have reported the interesting participation of Fe in the generation of the hydroxyl (OH) radical through the Fenton reaction that causes damage in plants (Konate et al., 2018).

It also affects the content of Malondialdehyde (MDA), activity of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), as well as in other bioactive compounds in the plant (Moradbeygi et al., 2020). Currently, the positive effect of foliar spraying of Fe NPs on the growth, development and quality production of some crops has been reported; however, many metabolic pathways have not been fully understood (Xiong et al., 2017).

Therefore, further research is needed to understand the effect of NPs on agricultural production (Shakoor et al., 2022), because their effect depends on the chemical species used, the concentration, size of NPs, biosynthesis, the route and stage of application (Lu et al., 2020). On the other hand, the cultivation of cucumber (Cucumis sativus L.) occupies 10% of the total area of greenhouses in Mexico (Valencia et al., 2018). In addition, its fruits contain various organoleptic properties, which are a source of minerals, fiber, vitamins and compounds with antioxidant activity (Preciado-Rangel et al., 2019). Therefore, the objective of this study was to evaluate the effect of foliar application of Fe2O3 NPs on yield and nutraceutical quality in cucumber cultivation.

Materials and methods

Study site and vegetative material

The experiment was established in a greenhouse located at the Antonio Narro Autonomous Agrarian University, Laguna Unit. Cucumber seeds of the Poinsett 76 variety (Southhern Start Seeds), of indeterminate growth, were used. The crop was established by direct sowing in black polyethylene bags with a capacity of 10 L, the substrate used was sand and perlite in an 80:20 ratio. The crop was trained to a single stem, irrigation and nutrition was with the Steiner (1961) nutrient solution (SN), which had an electrical conductivity of 2 dS m-1 and a pH of 5.5.

Characterization of nanoparticles

The iron oxide nanoparticles (Fe2O3 NPs) were donated by the Mexican company Investigación y Desarrollo de Nanomateriales S.A. de C.V. The NPs used were synthesized by wet chemical method in the form of iron oxide nanoparticles (maghemite: γ-Fe3O3), the size of the nanoparticles has an average of less than 50 nm, a purity level of 99.7% and a density of 5.81 g cm-3 (Gutiérrez-Ruela et al., 2021).

Experimental design and treatments

The experimental design used was random blocks. The treatments consisted of the foliar application of Fe2O3 NPs (0, 50, 75 and 100 mg L-1) with six repetitions. Foliar application of NPs was performed four times in the early morning hours every 15 days after planting. The harvest of the fruits was carried out from 70 days after planting. The yield, the commercial and nutraceutical quality were evaluated, in addition, the accumulation of Fe in the fruits was quantified.

Variables evaluated

The fruits of ten plants of each treatment were harvested, counting the weight, length and diameter of the fruits. Subsequently, eight fruits were randomly selected from each treatment for the analysis of commercial and nutraceutical quality.

Biomass, yield, total soluble solids and firmness

The yield (YI) was determined by harvesting the total fruits per plant, using a digital scale (VE-CB2000, VELAB), expressing the yield in kilograms per plant. The firmness of the fruit (FF) was measured using a penetrometer (FHT200, Extech instruments) with the plunger of eight mm in four fruits of each repetition, the fruits were placed on a flat and hard surface, three penetrations were made, which were averaged and recorded as maximum compressive force (N). The soluble solids of the fruits (TSS) were quantified in three fruits per repetition to make a composite sample, three drops of the juice were placed in a refractometer (MASTER-53α, ATAGO®) to be averaged and the reading expressed as Brix was obtained.

Chlorophyll index

The relative chlorophyll content index was measured at 30 days after transplantation using the Minolta SPAD-502 equipment. Five fully expanded leaves (without physical damage and avoiding veins) were taken from each plant and four plants per treatment in the flowering and harvesting stages. The results were expressed in SPAD units.

Photosynthetic pigments

Photosynthetic pigments were determined according to the methodology reported by Palacio-Márquez et al. (2021). Foliar samples of seven mm in diameter were taken during flowering, avoiding veins, 0.125 g was weighed in test tubes. Afterwards, 10 ml of methanol was added and left to react for 24 h in the dark. Finally, it was read at an absorbance of 666, 653 and 470 nm on a UV-Vis spectrophotometer (VE-5100UV, VELAB). The results were expressed in mg g-1 of fresh weight (FW) and calculated with the following formulas: Chla= [15.65(A666) - 7.34(A653)]. Chlb = [27.05(A653) - 11.21(A666)].

Preparation of extracts for nutraceutical quality

The extraction of the samples for the determination of total Phenols, Flavonoids and antioxidant activity was carried out following the methodology reported by (Cardeño, 2007), 2 g of fresh sample was homogenized with 10 mL of 80% ethanol (v:v). The homogenized sample was poured in test tubes, and they were stirred for 30 s in a Vortex, left to stand for 24 h in a rotary shaker (HZ-300) at 70 rpm and at room temperature. Extractions were performed by treatment and each repetition in triplicate.

Bioactive compounds

Total phenols

The phenolic content was determined by a modification of the colorimetric method of Folin-Ciacalteau (Singleton et al., 1999). Fifty microliters were diluted in 3 ml of distilled H2O, then 250 μl of Folin-Ciocalteau was added, a vortex was used for 30 s, and they were left to react for 3 min. Subsequently, 750 μl of Na2CO3 (7.5%) and 950 μl of distilled H2O were added. They were quantified in triplicate per repetition in the spectrophotometer (VE-5100UV, VELAB) with absorbance at 765 nm; a standard solution of gallic acid was prepared, the results were expressed in mg GA equivalents 100 g-1 of fresh weight (FW).

Total flavonoids

Total flavonoids were determined by a reported colorimetric method (Singleton et al., 1999). Two hundred fifty microliters of extract were taken, mixed with 1.25 ml of distilled water and 75 μl of NaNO2 (5%). They were left to stand for 5 min, 150 μl of AlCl3 (10%) was added (Sigma-Aldrich, St. Louis, MO, USA). Then 500 μl of NaOH 1M, 275 μl of distilled water were added and stirred vigorously. The samples were quantified in triplicate per repetition in the spectrophotometer (VELAB, VE-5100UV) with absorbance at 510 nm, a standard solution of quercetin was prepared. The results were expressed in mg QE g-1 FW.

Antioxidant activity

Antioxidant capacity was determined using the in vitro DPPH+ (Aldrich) method according to Brand-Williams et al. (1995). A solution of DPPH+ (Aldrich) in ethanol was prepared at a concentration of 0.025 mg ml-1. Fifty microliters of the extract were mixed with 1.95 μl of the DPPH+ solution, then they were left to stand for 30 min. They were quantified in triplicate per repetition in the spectrophotometer (VE-5100UV, VELAB) with absorbance at 517 nm. The results were expressed in μM Trolox equivalent 100 g-1 FW.

Vitamin C

Vitamin C (ascorbic acid) was determined by the method according to Hernández-Hernández et al. (2019). Ten grams of pulp were crushed with 10 ml of hydrochloric acid (2%), then filtered and measured with 100 ml of distilled H2O. Ten milliliters of the filtered solution were taken and titrated using a solution of 2,6 dichlorophenolindophenol (1 × 10-3 N). The concentration is expressed in mg 100-1 FW.

Total proteins

For the determination of the total protein, 3 g of fresh sample was homogenized in a mortar placed on ice, adding 0.1 g of polyvinylpolypyrrolidone (PVP) and 3 ml of a sodium-potassium solution (100 mM, pH 7 and 0.1 mM of EDTA) as an extraction buffer, then centrifuged at 1200 rpm at 5 °C for 5 min. The supernatant was used to determine total protein by the Bradford (1976) method using bovine serum albumin as standard. The results were expressed in mg g-1 FW.

Leaf iron content

The content was determined by acid digestion. Zero point five grams of leaf tissue and 1 g of dried pulp were weighed in a porcelain crucible, then placed in a furnace muffle (Thermo Scientific, Thermolyne) for 4 h at 600 °C, which began to be counted from the temperature of 200 °C. At the end of the time, the samples were pre-calcined in a burner, finally 5 ml of HCl at a concentration of 20% was added and filtered using ultrafine filter paper (Whatman) in volumetric flasks of 50 ml, measuring with deionized water. Iron concentration was measured with an Inductively Coupled Plasma Optical Spectrophotometer (ICP-OES) series 700 Agilent Technologies. The results were expressed in mg kg-1 dry matter (DM).

Statistical analysis

Data on the response variables were analyzed by analysis of variance and comparison of means with the Tukey test (p≤ 0.05) using the statistical package Statistical Analysis System Institute (SAS) version 9.3.

Results and discussion

Yield

Foliar spraying of Fe2O3 NPs affected the yield and quality of cucumber fruits (Table 1). With the application of 75 mg L-1, the greatest length of the fruit, TSS and YI were achieved, exceeding the control by 38.99%. Drostkar et al. (2016) applied Fe NPs in the cultivation of Cicer arietinum, as a result an increase in YI was observed compared to treatments without the application of NPs. The above results are explained by the size of the nanoparticle, which facilitates its absorption, as well as its adequate concentration for the metabolism of the plant (Kandpal et al., 2014).

Table 1. Yield, fruit length, firmness, total soluble solids, SPAD, chlorophyll and total protein in cucumber fruits, due to the foliar application of Fe2O3 NPs.

Values with equal letters in each column are statistically similar (Tukey p≤ 0.05).

Therefore, the YI and growth of the fruit could be affected by the NPs, altering its biological activities, causing the variations (Kanwar et al., 2019). Therefore, further studies are needed to explain the physiological effects of the use of metal NPs, at the same time, it is important to optimize the dose of Fe NPs considering the impact that this element has on the nutrition and development of the crop (Yuan et al., 2018; Shakoor et al., 2022).

Commercial quality of fruits

The largest size of the cucumber fruits was obtained with the foliar application of 75 mg L-1 of Fe2O3 NPs, exceeding the treatment without application of NPs by 23.26% (Table 1). Our results were similar within the ranges for commercialization. The adequate size of cucumber fruits for their commercialization fluctuates between 20 and 25 cm, it should not be less than 15 cm in length, while the equatorial diameter should be from 5 to 5.7, not exceeding 6 (Valencia et al., 2018).

On the other hand, with a higher dose of NPs (100 mg L-1), the size of the fruit’s decreases, this could be due to the bioavailability and high solubility of Fe2O3 NPs, which as long as the dose of NPs is higher, the absorption and ease of transport of nutrients in the plant could be lower (Moradbeygi et al., 2020). Regarding firmness and TSS, these were positively affected by foliar spraying of Fe2O3 NPs (Table 1), obtaining the greatest firmness in the fruit with 50 mg L-1 and in TSS with the dose of 100 mg L-1. According to Valencia et al. (2018), the average of 4.76 °Brix is the appropriate standard for cucumber fruit quality.

The increase in TSS content, according to Rawat et al. (2017), is due to the foliar application of Fe2O3 NPs, which induces a better efficiency in the regulation of the Rubisco enzyme, causing an increase in the chlorophyll content, therefore, increasing the photoassimilation in the fruits due to the range of photosynthesis, obtaining a better growth and bioaccumulation.

SPAD values and total chlorophyll

Foliar spraying of Fe NPs significantly affected the chlorophyll index and total chlorophyll. With the application of 100 mg L-1, the control treatment was exceeded by 35.24% in SPAD values and by 60.71% in total chlorophyll (Table 1). Rui et al. (2016) has reported an increase in SPAD units by increasing the dose of Fe2O3 NPs and Wang et al. (2019) has reported an increase in the total chlorophyll content with the application of Fe NPs, which means that, according to the dose applied, the deficiency of Fe in plants can be quickly corrected. Sharma et al. (2012) also reported an increase in the chlorophyll content in B. juncea treated with 100 mg L-1 of metal NPs.

It is evident that Fe has a direct influence on the concentration of chlorophyll, and this is affected depending on the concentration of NPs (Kanwar et al., 2019). However, it has been shown that the trend of chlorophyll content through the stages is in a constant decrease-increase-exchange (Wang et al., 2019). So, according to Rawat et al. (2017), depending on the concentration, stage of the plant and the time of application, the concentration of compounds such as chlorophyll content is promoted.

Total proteins

Leaf spraying of Fe2O3 NPs significantly affected the total protein content (Table 1). With the dose of 100 mg L-1, the values obtained without the application of Fe2O3 NPs were exceeded by 69%. It has been reported in Pisum sativum with the application of Fe NPs, compared to control treatment (Gutiérrez-Ruelas et al., 2021). Total soluble proteins are produced by plants to adapt to the environment (Shang et al., 2013), in turn they are produced when there is environmental stress, increasing the concentration of proteins or antioxidants, the latter are key to eliminating free radicals (Wang et al., 2019).

Bioactive compounds

With the foliar application of Fe2O3 NPs, an increase in the biosynthesis of bioactive compounds was obtained (Figure 1). Phenolic compounds and flavonoids are recognized for their benefits on human health (Elkhatim et al., 2018). In the present study, the highest concentration of phenolic compounds was achieved with doses of 50 mg L-1, exceeding the control by 27.12% (Figure 1a). While flavonoids obtained the highest concentration with 75 mg L-1, exceeding the control by 30.18% (Figure 1b). Similar results are reported in studies by Mogazy et al. (2022) in Fragaria ananassa and Cucumis melo L (Wang et al., 2019). In Arachis hypogaea, a higher antioxidant activity is reported (Rui et al., 2016); however, high concentrations of Fe NPs reduce non-enzymatic antioxidants.

Figure 1. Effect of Fe2O3 NPs on the content of phenolic compounds (a), flavonoids (b), in cucumber fruits. Columns with different letters differ statistically from each other (Tukey p≤ 0.05).

The above results can be explained by the regulatory functioning of iron in: 1) catalyst of overproduction of ROS such as H202 by Haber-Weiss, therefore, affecting the enzymatic line of defense (CAT, POD and SOD) and in the Fenton reaction (Mosa et al., 2018); 2) formation of MDA, lipid peroxidation (Konate et al., 2018); 3) interaction in cuticular wax due to foliar application of Fe NPs, as well as genes involved in intracellular wax synthesis and transport (Hu et al., 2017).

The response of crops to Fe NPs depends on the dose as this can affect various metabolic pathways (Yuan et al., 2018). Other reports indicate that the positive effect of Fe NPs is most evident when there is stress (Moradbeygi et al., 2020). Therefore, Fe is considered to be a dose-dependent element of regulation in crops, allowing metabolic and physiological adaptation mechanisms as long as it does not exceed its toxicity limit, since it functions as a response to oxidative stress caused by radicals under stress conditions (Hasanuzzaman et al., 2020).

Antioxidant capacity and vitamin C

Foliar spraying of Fe2O3 NPs positively affected antioxidant capacity and ascorbic acid (Figure 2). The highest concentration of antioxidant capacity was obtained with the application of 50 mg L-1 of Fe2O3 NPs, 39.18% higher than the control; with this same dose, the highest content of vitamin C was obtained, exceeding the content in the fruits of the control by 50%. Wang et al. (2019) reported a 46.95% increase in vitamin C content. Fe NPs produce oxidative stress, which activates a number of antioxidant mechanisms, stimulating the formation of ROS (Konate et al., 2018).

Figure 2. Effect of Fe2O3 NPs on antioxidant activity (a) and ascorbic acid content (b), in cucumber fruits. Columns with different letters differ statistically from each other (Tukey P≤ 0.05).

Fe content

Foliar spraying of Fe2O3 NPs significantly increased the foliar content of Fe in the cucumber (Figure 3). The highest concentration of Fe in leaves and fruit was found with the dose of 100 mg L-1, exceeding the control by 52.3% and 71.37%. Foliar spraying of 100 mg L-1 Fe2O3 NPs in Citrus maxima is reported to have increased malondialdehyde content by 44.7% (Hu et al., 2017), Fe content by 103% in Raphanus sativus (Shakoor et al., 2022).

Figure 3. Mineral content of iron in leaf (a) and fruit (b) with the application of Fe2O3 NPs. Columns with different letters differ statistically from each other (Tukey P≤ 0.05).

Therefore, the above results are due to the fact that most NPs are trapped in the surface wax, promoting the formation of bunches and agglomerates (Hu et al., 2017). Therefore, the spraying of Fe2O3 NPs affects the development of the plant, these impacts are associated with the application of the dose and its integration into its foliar system (Lu et al., 2020). The nano-biofortification of cucumber is an alternative to complement human nutrition by increasing the Fe content in the fruits, which can be used by humans for energy production, oxygen utilization/transport and cell proliferation (Lynch et al., 2018).

The doses used could help meet the daily requirements of 7.8-10 mg day-1 for infants, adolescents of 11-15 mg day-1 and adults of 10-20 mg day-1 (Blanco-Rojo and Vaquero, 2018). Avoiding cardiovascular risks, chronic diseases, reducing cases of anemia and mortality (Blanco-Rojo and Vaquero, 2018).

Conclusions

Foliar application with Fe2O3 NPs improved the yield, the content of bioactive compounds and their bioaccumulation, as well as the content of Fe in cucumber fruits. The highest yield and biosynthesis of bioactive compounds was achieved with the treatments of 50 and 75 mg L-1 of Fe2O3 NPs 50, while the highest concentration of Fe in leaves and fruits was achieved with 100 mg L-1. The foliar spraying of Fe2O3 NPs is an alternative to increase agricultural production and biosynthesis of bioactive compounds, in addition to promoting their bioaccumulation of Fe in cucumber fruits.

Acknowledgements

Reyna Roxana Guillén Enríquez thanks the National Council of Science and Technology (CONACYT, for its acronym in Spanish) for the financial support to continue her preparation in the Doctorate in Water Sciences and Soil at the Technological Institute of Torreón (ITT, for its acronym in Spanish). As well as the technical assistance of the laboratory and advice. At the same time, she thanks the collaboration with the Antonio Narro Autonomous Agrarian University (UAAAN, for its acronym in Spanish) and the Department of Agroecology for the facilitations provided for the development of this study.

Cited literature

Abbasifar, A.; Shahrabadi, F. and ValizadehKaji, B. 2020. Effects of green synthesized zinc and copper nano-fertilizers on the morphological and biochemical attributes of basil plant. J. Plant Nutr. 43(8):1104-1118.

Blanco, R. R. and Vaquero, M. P. 2018. Iron bioavailability from food fortification to precision nutrition. A review. Innovative Food Sci. Emerging Technol. 51(1):126-138.

Bradford, M. M. 1976. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 72(1-2):248- 254.

Brand, W. W.; Cuvelier, M. E. and Berset, C. L. 1995. Use of a free radical method to evaluate antioxidant activity. LWT-Food Sci. Technol. 28(1):25-30.

Cardeño, Á. V.; Molina, M. C.; Miranda, I.; García, G. T.; Morales, J. M. and Stashenko, E. E. 2007. Actividad antioxidante y contenido total de fenoles de los extractos etanólicos de Salvia aratocensis, Salvia sochensis, Bidens reptons y Montanoa ovalifolia. Scientia et Technica. 13(33):205-207.

Drostkar, E. Talebi, R. and Kanouni, H. 2016. Foliar application of Fe, Zn and NPK nano-fertilizers on seed yield and morphological traits in chickpea under rainfed condition. J. Res. Ecol. 4(2):221-228.

Elkhatim, K. A.; Elagib, R. A. and Hassan, A. B. 2018. Content of phenolic compounds and vitamin C and antioxidant activity in wasted parts of Sudanese citrus fruits. Food Sci. Nutr. 6(5):1214-1219.

Gutiérrez, R. N. J.; Palacio, M. A.; Sánchez, Ch. E.; Muñoz, M. E.; Chávez, M. C.; Ojeda, B. D. L. and Flores, C. M. A. 2021. Impact of the foliar application of nanoparticles, sulfate and iron chelate on the growth, yield and nitrogen assimilation in green beans. Notulae Botanicae Horti Agrobotanici Cluj-Napoca. 49(3):12437-12437.

Hasanuzzaman, M.; Bhuyan, M. B.; Raza, A.; Hawrylak, N. B.; Matraszek, G. R.; Mahmud, J; Nahar, K. and Fujita, M. 2020. Selenium in plants: boon or bane? Environ. Exp. Bot. 178(10):1-41.

Hu, J.; Guo, H.; Li, J.; Wang, Y.; Xiao, L. and Xing, B.2017. Interaction of γ-Fe2O3 nanoparticles with Citrus maxima leaves and the corresponding physiological effects via foliar application. J. Nanobiotechnol. 15(1):1-12.

Kandpal, N. D.; Sah, N.; Loshali, R.; Joshi R. and Prasad, J. 2014. Co-precipitation method of synthesis and characterization of iron oxide nanoparticles. J. Sci. Industrial Res. 73(2):87-90.

Konate, A.; Wang, Y.; He, X.; Adeel, M.; Zhang, P.; Ma, Y.; Ding, Y.; Zhang, J.; Yang, J.; Kizito, S.; Rui, Y. and Zhang, Z. 2018. Comparative effects of nano and bulk-Fe3O4 on the growth of cucumber (Cucumis sativus L). Ecotoxicol. Environ. Safety. 165(9):547-554.

Li, M.; Zhang, P.; Adeel, M.; Guo, Z.; Chetwynd, A. J.; Ma, C.; Bai, T.; Hao, Y. and Rui, Y. 2021. Physiological impacts of zero valent iron, Fe3O4 and Fe2O3 nanoparticles in rice plants and their potential as Fe fertilizers. Environ. Pollution. 269(1):116134-116146.

Lowry, G. V.; Avellan, A. and Gilbertson, L. M. 2019. Opportunities and challenges for nanotechnology in the Agri-Tech Revolution. Nature Nanotechnol. 14(6):517-522.

Lu, K.; Shen, D.; Liu, X.; Dong, S.; Jing, X.; Wu, W. and Mao, L. 2020. Uptake of iron oxide nanoparticles inhibits the photosynthesis of the wheat after foliar exposure. Chemosphere. 259(1):127445-127453.

Mogazy, A. M.; Mohamed, H. I. and Mahdy, O. M. 2022. Calcium and iron nanoparticles: a positive modulator of innate immune responses in strawberry against botrytis cinerea. Process Biochem. 115(1):128-145.

Moradbeygi, H.; Jamei, R.; Heidari, R. and Darvishzadeh, R. 2020. Investigating the enzymatic and non-enzymatic antioxidant defense by applying iron oxide nanoparticles in dracocephalum moldavica L. plant under salinity stress. Sci. Hortic. 272(1):109537-109545.

Mosa, K. A.; Naggar, M.; Ramamoorthy, K.; Alawadhi, H.; Elnaggar, A.; Wartanian, S.; Ibrahim, E. and Hani, H. 2018. Copper nanoparticles induced genotoxicty, oxidative stress, and changes in superoxide dismutase (SOD) gene expression in cucumber (Cucumis Sativus L.) Frontiers Plant Sci. 9(7):1-13.

Preciado, R. P.; Valenzuela, G. A. A.; Pérez, G. L. A.; González, S. U.; Ortiz, D. S. A.; Buendía, G. A.; Edgar, O. y Rueda, P. 2022. La biofortificación foliar con hierro mejora la calidad nutracéutica y la capacidad antioxidante en lechuga. Terra Latinoam. 40(1):1-7.

Rawat, M.; Nayan, R.; Negi, B.; Zaidi, M. G. H. and Arora, S. 2017. Physio-biochemical basis of iron-sulfide nanoparticle induced growth and seed yield enhancement in B. Juncea. Plant Physiol. Biochem. 118(1):274-284.

Rui, M. Ma, C. Hao, Y. Guo, J. Rui, Y. Tang, X. and Sperotto, R. A. 2016. Iron oxide nanoparticles as a potential iron fertilizer for peanut (Arachis hypogaea). Frontiers Plant Sci. 7(9):1-10.

Sega, D.; Ciuffreda, G.; Mariotto, G.; Baldan, B.; Zamboni, A. and Varanini, Z. 2019. FePO4 nanoparticles produced by an industrially scalable continuous-flow method are an available form of P and Fe for cucumber and maize plants. Scientific Reports. 9(1):1-13.

Shakoor, N.; Adeel, M.; Zain, M.; Zhang, P.; Arslan, M.; Farooq, T.; Zhou, P.; Azeem, I.; Rizwan, M.; Guo, K.; Jilani, G.; Ahmar, S.; Maqbool, S. and Ming, X. 2022. Iron-based nanoparticles enhances its nutritional quality by trigging the essential elements. NanoImpact. 25(1):100388-100393. 

Shang, F. F.; Zhao, X. P.; Chang, W. U.; Li, Y. W. U.; Hou, Q. and Wang, Q. 2013. Effects of chlorpyrifos stress on soluble proteins and some related metabolic enzyme activities in different crops. J. China Agricultural University. 18(4):105-110.

Singleton, V. L.; Orthofer, R. and Lamuela, R. R. M. 1999. Analysis of total phenols and other oxidation substrates and antioxidants by means of folin-ciocalteu reagent. Methods in Enzymology. 299(14):152-178.

Steiner, A. A. 1961. A universal method for preparing nutrient solutions of a certain desired composition. Plant and Soil. 15(1):134-154.

Tripathi, A. and Mishra, S. 2020. An estimation of price effects of making food fortification mandatory in India. Food and Nutrition Bulletin. 41(3):355-366.

Valencia, R. T.; Acosta, L. S.; Hernández, M. F.; Rangel, P. P.; Robles, M. Á. G., Cruz, R. C. A. and Vázquez, C. V. 2018. Effect of seaweed aqueous extracts and compost on vegetative growth, yield, and nutraceutical quality of cucumber fruit. Agronomy. 8(11):1-13.

Wang, J.; Ren, T.; Wang, F.; Han, Y.; Liao, M.; Jiang, Z. and Liu, H. 2016. Effects of dietary cadmium on growth, antioxidants and bioaccumulation of sea cucumber (Apostichopus japonicus) and influence of dietary vitamin C supplementation. Ecotoxicol. Environ. Safety. 129(1):145-153.

Wang, X. P.; Li, Q. Q.; Pei, Z. M. and Wang, S. C. 2018. Effects of zinc oxide nanoparticles on the growth, photosynthetic traits, and antioxidative enzymes in tomato plants. Biologia Plantarum. 62(4):801-808.

Wang, Y.; Wang, S.; Xu, M.; Xiao, L.; Dai, Z. and Li, J. 2019. The impacts of g -Fe2O3 and Fe3O4 nanoparticles on the physiology and fruit quality of muskmelon (Cucumis melo) plants. Environ. Pollution. 249(1):1011-1018.

Xiong, T.; Dumat, C.; Dappe, V.; Vezin, H.; Schreck, E.; Shahid, M. and Sobanska, S. 2017. Copper oxide nanoparticle foliar uptake, phytotoxicity, and consequences for sustainable urban agriculture. Environ. Sci. Technol. 51(9):5242-5251.

Yuan, J.; Chen, Y.; Li, H.; Lu, J.; Zhao, H.; Liu, M. and Glushchenko, N. N. 2018. New insights into the cellular responses to iron nanoparticles in Capsicum annuum. Scientific Reports. 8(1):1-9.

Yusefi, T. E.; Fallah, S.; Rostamnejadi, A. and Pokhrel, L. R. 2020. Zinc oxide nanoparticles (ZnONPs) as a novel nanofertilizer: influence on seed yield and antioxidant defense system in soil grown soybean (Glycine max cv. Kowsar). Sci. Total Environment. 738(1):140240-140259. 

Zhou, Z. D. and Tan, E. K. 2017. Iron regulatory protein (IRP) iron responsive element (IRE) signaling pathway in human neurodegenerative diseases. Molecular Neurodegeneration. 12(1):1-12.