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Article

Enhancement of Rose Scented Geranium Plant Growth, Secondary Metabolites, and Essential Oil Components through Foliar Applications of Iron (Nano, Sulfur and Chelate) in Alkaline Soils

by
Amany E. El-Sonbaty
1,
Saad Farouk
2,*,
Hatim M. Al-Yasi
3,
Esmat F. Ali
3,*,
Atef A. S. Abdel-Kader
4 and
Seham M. A. El-Gamal
5
1
Soil, Water and Environment Research Institute, Agriculture Research Centre, El-Gama St., Giza 3725004, Egypt
2
Agricultural Botany Department, Faculty of Agriculture, Mansoura University, Mansoura 35516, Egypt
3
Department of Biology, College of Science, Taif University, Taif 21944, Saudi Arabia
4
Department of Medicinal and Aromatic Plants, Horticulture Research Institute, Agricultural Research Center, Giza 12619, Egypt
5
Medicinal and Aromatic Plants Research Department, Horticulture Research Institute, Agricultural Research Center, Giza 12619, Egypt
*
Authors to whom correspondence should be addressed.
Agronomy 2022, 12(9), 2164; https://doi.org/10.3390/agronomy12092164
Submission received: 21 August 2022 / Revised: 5 September 2022 / Accepted: 7 September 2022 / Published: 11 September 2022
(This article belongs to the Special Issue Crop Nutrient Requirements and Advanced Fertilizer Management Strategies)
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Abstract

:
Iron (Fe) deficiency exists as a widespread nutritional disorder in alkaline and calcareous soils; therefore, Fe-enriching strategies may be used to overcome this issue. Field experiments were conducted with a randomized complete design with three replicates for evaluating the effectiveness of iron oxide nanoparticles (Fe-NPs) against traditional Fe compounds (sulfate or chelate), which have various shortcomings on Rose-scented geranium (RSG) herb in terms of plant growth, phytopharmaceuticales, essential oil (EO), and its constituents. Supplementation of Fe-sources considerably improved RSG plant growth and EO yield in the 1st and 2nd cut throughout the two seasons over non-treated control plants. A total of 11 compounds of RSG-EO were identified; the main constituents were citronellol, geraniol, and eugenol. The results indicate that EO composition was significantly affected by Fe-sources. Amendments of Fe-sources considerably augmented photosynthetic pigments, total carbohydrates, nitrogen, phosphorous, potassium, iron, manganese, zinc, phenols, flavonoids, and anthocyanin. Commonly, Fe-NPs with humic acid (Fe-NPs-HA) supplementation was superior to that of traditional sources. The highest values were recorded with spraying Fe-NPs-HA at 10 mg L−1 followed by 5 mg L−1, meanwhile, the lowest values were recorded in untreated control plants. Current findings support the effectiveness of nanoparticle treatment over Fe-sources for improving growth and yield while also being environmentally preferred in alkaline soil. These modifications possibly will be applicable to EO quality and its utilization in definite food and in medical applications.

1. Introduction

Rose-scented geranium (RSG, Pelargonium graveolens L. Her. ex Ait. ‘Synonym Prasophyllum roseum Willd.’; Geraniaceae) is a highly valued perennial aromatic shrub worldwide [1]. The chief RSG production takes place in China and the Middle East, i.e., Egypt [2]. Its EO is extensively used in the perfumery, cosmetic, and aromatherapy industries [1,3,4]. Additionally, they are becoming increasingly popular for several human disorders, i.e., relieving dysentery, cancer, sterility, urinary stones, and liver complications [5,6]. The main constituents of RSG-EO are citronellol (19.28–40.23%), geraniol (6.45–18.40%), linalool (3.96–12.90%), iso-menthone (5.20–7.20%), citronellyl formate (1.92–7.55%), Guaia-6,9-diene (0.15–4.40%), and bits of more than 100 constituents [1,4]. Accordingly, EO composition is strongly affected by environmental factors and micronutrients including iron [7,8].
Iron (Fe) represents the 4th supreme plentiful element in the earth’s crust, which participates in several species’ physio-biochemical pathways [9,10]. It is a co-factor for approximately 140 enzymes elaborated in photosynthesis, gas exchange, nitrogen fixation, and nucleic acid assimilation [11,12]. It is also involved in chlorophyll biosynthesis, chloroplast development, and electron transport systems [13,14]. Iron deficiency (FDS) is a widespread threat affecting 30–50% of cultivated alkaline soils in dry regions, i.e., Egyptian soil [15,16]. Considering the soil–plant–animal–human food chain FDS not only affects plant growth and development but can also accelerate anemia in animals and humans [1]. Therefore, usage of the proper amount and forms of Fe is a prerequisite to extra studies, to lessen FDS, and to increase nutrient-use efficiency. Presently, several products were applied to overcome FDS. The EU Directive No. 2003/2003 [17,18] comprises chelates i.e., ethylene diaminetetraacetic acid (Fe-EDTA) and ethylenediamine-N, N′-biso-hydroxyphenyl acetic acid (Fe-o,o-EDDHA) complexes; and inorganic salts as a promising method for improving Fe uptake and lessens Fe-chlorosis. The effectiveness of inorganic and chelated Fe fertilizers in mitigating FDS is exceedingly variable depending on their solubility, constancy, infiltration capacity via leaf cuticle and translocation into the plant tissues [19,20]. The usage of Fe chelates does not represent a viable approach for agronomists to avoid Fe chlorosis as a result of the excessive cost and ecological hazards [21]. Furthermore, most of these chelates are recalcitrant products in soils and waters, and there has been developing anxiety recently about the ecological threat of their amendment to soils [22].
Recently, there has been a thrust to develop innovative nanoparticle (NP) fertilizer formulations including iron nano-oxide (Fe-NPs), for reducing the quantity of conventional fertilizers owing to (1) their unique physical and chemical attributes (small size, huge surface area, pureness, and steadiness), and (2) the interface amongst nanoparticles and biomolecules possibly will provoke metabolic pathways in treated plants [8,18,23]. The stimulating impact of Fe-NPs on the growth and economic yield of different herbs has been reported previously [8,23,24]. In this regard, El-Khateeb et al. [8] on sweet marjoram found that Fe-NPs foliar spraying augmented plant growth, chlorophyll concentration, carbohydrates, EO %, and yield as well as their constituents. Nejad et al. [25] found that Fe-spraying increased the photosynthetic pigments, phenols, and EO % of RSG plants. Gutierrez-Ruelas et al. [18] recorded that Fe-NPs spraying increased green bean plant biomass, total chlorophyll, and Fe content as well as nitrate reductase activity.
However, it is unclear how Fe-NP supplementation affects RSG plant development and some biochemical characteristics when used in place of conventional Fe-sources. As a result, the main goal of the current study is to determine the effects of Fe-sources (chelate, sulfur, and nano) on the growth of RSG, EO content, and their constituents, as well as their phytochemicals. We hypothesized that various Fe sources have varying effects on plant growth, EO yield, and composition as well as phytopharmaceuticals production. As a novel Fe source, Fe-NPs were also very successful in eliciting the accumulation of phytopharmaceuticals, as well as boosting EO yield and plant antioxidant activity.

2. Materials and Methods

2.1. Assimilation of Fe-NPs

The synthesis of magnetic iron oxide nanoparticles (Fe-NPs) was created with an eco-friendly adapted scheme [26]. The co-precipitation method synthesized the Fe-NPs in situ, which is a classical method for Fe3O4 generation. Concisely, 6.1 g of ferric chloride was dissolved in 100 mL of distilled water, subsequently, the addition of an aliquot of concentrated HCl to evade Fe(OH)3 precipitation, afterward 4.2 g of FeSO4·7H2O were dissolved in a mix, and heated to 90 °C, then 10 mL of NH4OH (25%) was poured quickly, and pH of the solution was sustained at 10. The mixture was stirred at 90 °C for 30 min and then cooled to lab temperature. The black substance was collected via centrifugation at 600× g, and then washed with ethanol and distilled water.

2.2. Characterization of Fe-NPs

The dimension and shape of Fe-NPs were detected by transmission electron microscopy (TEM, JEOL Ltd. Tokyo, Japan). The TEM samples were prepared via dropping solution on a carbon-coated copper grid and then exposed to the infra-light for 30 min (Okenshoji Co., Ltd., Tokyo, Japan microgrid B). The micrograph was examined by JEOL-JEM 6510 at 70 kV in the RCMB, Mansoura University, Egypt.

2.3. Experimental Location, Climate Data, and Soil Properties

Two field experiments were done at a private farm in El-Serw City (31°14′19.21″ N, 31°39′13.64″ E; 16 m ASL), Damietta, Egypt, during the 2018 and 2019 seasons for assessing the response of RSG plant growth, yield, and EO content to foliar applications of Fe-sources. Physical-chemical examination of the soil surface (0–60 cm) was employed before transplanting [27]. The soil texture was clay, and its properties were recorded in Table 1. Diurnal experimental site ecological information involved temperature, solar radiation, relative humidity, and wind speed of the 1st and 2nd seasons as presented in Supplementary Materials Table S1.

2.4. Experimental Layout

The experimental soil was mechanically plowed twice prior to transplantation until the soil surface was steady and established in the plots. Uniform seedlings of 25–30 cm length (from the Dept. of Medicinal and Aromatic Plants, Ministry of Agric., Egypt) were individually transplanted on 1st March, during the 2018 and 2019 seasons, in 3 × 3.5 m plots, rows with 60 cm apart and 60 cm amongst the seedlings. In both seasons, the plants were received the recommended doses of mineral fertilizers (ammonium sulfate ‘20.5%’, calcium superphosphate ‘15.5%’, and potassium sulfate ‘52%’ at 200, 100, and 55 kg/fed. ‘4200 m2′, correspondingly) before planting and once first cut in both seasons. Entirely agricultural practices of plants were carried out following the endorsements of the Ministry of Agriculture, Egypt. The design of the experiment was completely randomized that contained 11 treatments at three replicates, and they are displayed in Table 2. The preliminary study provided the basis for choosing this concentration. The Fe-forms were sprayed directly on the plants four times at 45 and 60 days (for the 1st cut), and 135 and 150 days (for the 2nd cut) from transplanting (15 days prior to flowering and at the start of the flowering stage in both cuts).

2.5. Measurements and Data Collection

Plants were harvested (cuts) 10 cm above the soil two times at full bloom (after 90 and 180 days from transplanting) in each season for determining growth characteristics (plant height ‘cm’, branches number/plant, shoot fresh and dry weights ‘g/plant’) and EO (%, yield/plant, yield/fed.), meanwhile both cuts in the second season was used for determining photosynthetic pigments, ions, phytopharmaceuticals, and EO composition.

2.6. Determination of Essential Oil

Using a modified Clevenger apparatus for three hours, the EO was hydro-distilled from the air-dried plants that had been in the shade for 48 h [28]. After distillation, the EO was dried by a glass separator, filtered two times, kept in the fridge at 4 °C, and preserved in dark closed bottles for preventing light and oxygen exposure. EO % = (EO volume/shoot fresh weight) × 100. The EO yield (mL/plant) was calculated following the current equation; EO yield = shoot fresh weight (g) × EO%.
The EO components were recognized, with a Varian Chrompack CP-3800 gas chromatograph (Varian Company, California, USA) with a mass detector (4000 GC-MS/MS). Helium served as the gas carrier at a flow rate of 2 mL min−1 with a linear velocity of 32 cm s−1. The flame ionization detector temperature was 265 °C and the injector temperature was 250 °C. Detection of the constituents was dependent on a judgment of their mass spectra with those of a computer library or with realistic composites and validation of compound individualities was also gained via Retention index (RI) assessed regarding a homologous series of C5–C24 (n-alkanes) as designated by Adams [29].

2.7. Ion Concentration

Nitrogen (N), and phosphorus (P) were extracted and estimated [30] from the plant dry shoot. Roughly 0.2 g shoot dry mass was cautiously moved to a digestion flask with 5 mL of concentrated H2SO4, at 100 °C for 2 h; then, the combinations were cool for 15 min in lab temperature. An aliquot of H2SO4/HClO3 mix was poured dropwise. Total N was assessed with the micro-Kjeldahl scheme. The outline of Cooper [31] was followed for the assessment of P alongside the phosphate standard curve. In the meantime, the potassium (K), Fe, manganese (Mn), and zinc (Zn) were extracted by acid digestion (70% nitric acid and 35% hydrochloric acid) in a Milestone MLA 1200 Mega microwave digestion device, then estimated using iCAPTM 7000 Plus Series ICP-OES (Thermo ScientificTM, Boston, MA, USA, Boston) following Bettinelli et al. [32] protocol.

2.8. Photosynthetic Pigment

Chlorophylls and carotenoids were assessed by Lichtenthaler and Wellburn [33] procedure. Generally, 0.2 g FW from the 4th upper leaves was extracted overnight in pre-cooled methanol (96%) accompanied by 0.05% sodium bicarbonate. The optical density (OD) was read at 470, 653, and 666 nm spectrophotometrically (T60 UV–Visible spectrophotometer, Leicestershire, UK). Pheophytin (Pheo) and Chlorophyllide (Chlide) were assessed in the 4th upper leaves according to Radojevic and Bashkin [34] and Harpaz-Saad et al. [35], respectively. On the other hand, the protocol described by Sarropoulou et al. [36] was applied for the estimation of protoporphyrin (Proto), Mg-protoporphyrin (Mg-Proto), and protochlorophyllide (Pchlide).

2.9. Total Carbohydrates

The colorimetric technique designated by Zhang et al. [37] was used to estimate total carbohydrate concentrations in plant shoots using 3, 5-dinitrosalicylic acid (DNS), after extraction with hot ethanol (80%). An aliquot of shoot extract (3 mL) was mixed with 3 mL DNS reagent in a test tube, then heated in a boiling water bath for 5 min. Consequently, 40% Rochelle salt solution (1 mL) was quickly added, to the mix, and placed in a water bath at lab temperature for about 25 min., subsequently; the OD at 510 nm is recorded with a spectrophotometer (T60 UV–Visible spectrophotometer, Leicestershire, UK).

2.10. Total Phenolic Compounds, Total Flavonoids, and Total Anthocyanin

The Folin–Ciacolteu procedure was utilized spectrophotometrically (T60 UV–Visible spectrophotometer, Leicestershire, UK) to estimate the total phenolic concentration [38]. Concisely, the ethanolic plant extract was added to the Folin–Ciocalteu reagent and sodium carbonate solution (20%), homogenized, and incubated in the dark for 30 min. The OD was then measured at 650 nm. A calibration curve for gallic acid was used to estimate their concentration (mg gallic g−1 DW).
The technique established by Meda et al. [38] was employed to assess the total concentration of flavonoids (mg quercetin g−1 DW) using the aluminum chloride colorimetric scheme. An aliquot of ethanolic extract, 0.1 mL of aluminum chloride, 0.1 mL of sodium acetate, and 2.8 mL of distilled water was combined and stirred. The mixture’s OD was deliberate spectrophotometrically (T60 UV–Visible spectrophotometer, Leicestershire, UK) at a wavelength of 415 nm.
Total anthocyanin concentration was determined according to the method of Abdel-Aal and Hucl [39], in which the OD of each pre-chilled acidified methanolic extract was assessed spectrophotometrically (T60 UV–Visible spectrophotometer, UK) at 530 nm. The concentration (mg 100 g−1 FW) was expressed as cyaniding-3-glucoside using a molar extinction coefficient of 27.900.

2.11. Statistical Analysis

The similarity of variables error variance was performed earlier in the analysis of variance (ANOVA). The outputs demonstrated that all data satisfied the uniformity to accomplish further ANOVA checks. The data acquired were exposed to one way-ANOVA at a 95% confidence level by CoHort Software, 2008 statistical package (CoHort software, 2006; Raleigh, NC, USA). The mean values of treatments were compared via Tukey’s HSD-MRT test at p ≤ 0.05. Values attended by diverse letters were significantly different at p ≤ 0.05. The data presented are mean values ± standard error (SE). The levels of significance were denoted by * p < 0.05, ** at p < 0.01, *** p < 0.001 and NS, no significant.

3. Results

3.1. Magnetite Nanoparticles Characterization

By using TEM imaging, the physicochemical properties of Fe-NPs were considered (Figure 1). The images of synthesized magnetite nanoparticles with an average particle size of 9–14 nm and a large number of diffraction rings characteristic of crystalline spherical Fe-NPs. The nanoparticles used in this study have a mean diameter of 12.6 nm, suggesting that the particles can cross bio-membranes.

3.2. Morphological Characterization

Data in Table 3 shows that application of Fe-sources significantly increased the growth parameters in both the 1st and 2nd cut in both seasons over control plants. The highest morphological values were significantly associated with RSG treated with Fe-NPs HA at 10 mg L−1, followed by 5 mg L−1 Fe-NPs HA, correspondingly, and mostly, they produced equivalent effects in both seasons. Meanwhile, the lowest values were usually detected in a non-treated plant, with statistical significance.

3.3. Essential Oil Yield

Data presented in Figure 2A–F indicate that Fe-sources supplementation significantly raised EO %, accompanied by increasing EO yield per plant and per fed. in both cuts relative to control plants (water spraying plants). The highest EO %, EO yield per plant, and EO yield per fed. were recorded by spraying Fe-NPs-HA at 10 mg L−1 followed by 5 mg L−1, meanwhile, the lowest values were recorded in control plants. In this regard, EO% of the 1st cut ranged from 0.132 to 0.293% based on air-dry weight, meanwhile it was 0.101 to 0.192% in the 2nd cut in the first season. On the other hand, it was from 0.137 to 0.295% in the 1st cut and from 0.103 to 0.209% in the second cut, respectively, in the second season.
Regarding EO yield per plant and per fed., the results showed that Fe-sources spraying had a significant impact on EO yield at both harvests in the first and second seasons. In most cases, the yield was slightly higher in the 1st cut than in the 2nd cut in both seasons. In the first season, the EO yield per plant and fed. in the first cut was 0.819–4.577 mL/plant and 13.374–74.737 L/fed. meanwhile the 2nd cut recorded 0.849–4.740 mL/plant and 13.869–77.396 L/fed. respectively (Figure 2). Additionally, in the second season, the EO yield/plant recorded 0.888–4.676 mL/plant in the first cut and 0.876–5.201 mL/plant in the second cut. Meanwhile, the EO yield/fed. was 14.510–76.354 and 14.313–84.924 in the 1st and 2nd cut, respectively. The highest EO yield per plant and per fed. In the 1st and 2nd cut throughout both seasons was obtained in plants sprayed with 10 mg L−1 Fe-NPs-Ha and the lowest values were detected in untreated plants.

3.4. Chemical Composition of Essential Oils

Rose-scented geranium EO was slightly light green with a 0.889 g/mL density. The data belonging to qualitative and quantitative constituents of EO, collected from the 1st and 2nd cuts during the 2019 season of RSG herbs subjected to Fe-sources foliar application were identified (Table 4 and Table 5). In total, 11 constituents were detected in EO accounting for 86.04% and 91.55% of the total EO in the 1st and 2nd cut respectively. A comparison of the entire set of EO analytical data showed significant variations in the EO’s qualitative and quantitative composition as a result of the use of Fe-sources.
Citronellol and geraniol were the main ingredients of RSG-EO with treatments in the 1st cut, accounting for 18.29–25.58% and 19.09–36.88% of the total. There were also moderate amounts of eugenol (6.21–13.23%), geranyl formate (5.33–9.14%), citronelyl formate (5.43–9.11%), linalool (4.21–8.01%), and isomenthone (3.36–6.60%), as well as very variable amounts of α-pinene (0.13–1.37%), myrcene (0.12–1.46%), geranyl butyrate (0.43–9.23%), and β-caryophyllene (1.38–5.01%). According to Table 4’s findings, 5 mg L−1 Fe-NPs-HA was used to produce the maximum levels of citronellol, citronely formate, linalool, and isomenthone. Meanwhile, the application of 10 mg L−1 Fe-NPs-HA, 100 mg L−1 EDTA, 200 mg L−1 EDTA, and 200 mg L−1 FeSO4 correspondingly resulted in the greater amount of α--pinene, geranyl formate, geraniol, and β--caryophyllene.
Citronellol (26.07–36.97%) and geraniol (11.28–24.41%) made up the majority of RSG-EO in the second cut with all treatments (Table 5). There were also moderate amounts of eugenol (5.20–13.33%), geranyl formate (2.76–6.27%), citronelyl formate (6.99–9.35%), linalool (2.48–12.78%), isomenthone (4.20–6.98%), and very variable amounts of α-pinene (0.30–1.31%), myrcene (0.35–1.41%), geranyl butyrate (0.85–3.61%), and β-caryophyllene (0.76–4.48%). The results in Table 4 demonstrate that 5 mg L−1 Fe-NPs were necessary to produce the greatest amount of geranyl formate and geraniol. Meanwhile, myrcene, isomenthone, citronellol (100 mg L−1 EDTA), geranyl butyrate, eugenol (100 mg L−1 FeSO4), and β-caryophyllene (200 mg L−1 EDDHA) are present in larger concentrations.
Citronellol (C), geraniol (G), and their esters are the quality features in RSG-EO. Different C/G ratio was established in RSG herbs at the 1st and 2nd cut (Table 4 and Table 5). In the 1st cut, the C/G ratio (from 0.621 to 1.107), additionally, the maximum C/G ratio (1.107) was recorded in T4 after that T3 (1.005) as compared with T1 (0.933). Similarly, in the 2nd cut, the C/G ratio varied from 1.071 to 2.809, with the maximum C/G ratio documented in T4 (2.809) followed by T8 (2.478) relative to T1 (2.029).

3.5. Measurement of Chlorophyll and Its Assimilation and Chlorophyll Precursor

Foliar spraying of Fe-forms significantly improved total chlorophyll and carotenoid concentrations in RSG leaves above the control plants. It is observed from the data also that Fe-NPs in special with humic acid were most effective than other Fe-forms. The greatest chlorophyll and carotenoid concentrations were obtained after 10 mg L−1 Fe-NPs-HA spraying, which increased by 136 and 70% in the first cut and by 118 and 98% in the second cut respectively, over control plants (Table 6).
Table 6 shows that application of Fe-sources especially 10 mg L−1 Fe-NPs-HA significantly increased Pheo, Achl a, Chl a/Chlide, and Chl b/Chlide comparative to non-treated herbs. Additionally, Table 6 designates that porphyrin intermediate assimilation (Mg-proto, proto, and Pchlide) was considerably decreased by Fe-sources supplementation.

3.6. Measurement of Ion Levels

Data existing in Table 7 display that Fe sources supplementation significantly amplified the level of ions in plant shoots in both cuts over untreated control plants. Additionally, the data also indicate that the usage of nano-forms of iron was superior to traditional sources in increasing the ion level on plant shoots. The greatest values of nitrogen (3.33 and 3.97%), phosphorous (0.222 and 0.222%), potassium (2.07 and 2.45%), iron (443 and 534 mg g−1), manganese (89.7 and 43 mg g−1), and zinc (87 and 89.7 mg g−1) in the first cut and second cut, respectively, were recorded when plant sprayed twice with 10 mg L−1 Fe-NPs-HA relative to other treatments or control plants.

3.7. Total Carbohydrate

Data in Table 8 displayed that, in general, the spraying of Fe sources increased significantly total carbohydrate concentration in the plant shoot over untreated control plants. The highest carbohydrate concentration was documented under the treatment of foliar application with 10 mg L−1 Fe-NPs-HA as compared with other treatments or untreated control plants.

3.8. Phytopharmaceuticals

As shown in Table 8, the spraying of Fe-forms significantly increased the leaf phytopharmaceutical concentrations (phenol, flavonoid, and anthocyanin) in relation to nontreated plants. The supreme of phenols (14.27 and 14.83 mg gallic acid g−1 DW), flavonoids (2.762, and 3.007 mg quercetin g−1 DW), and anthocyanin (4.238, 5.183 mg 100 g−1 FW) concentrations in both cuts were recorded in the plant shoot treated with 10 mg L−1 Fe-NPs-HA. On the other hand, the lower levels of phytopharmaceuticals were recorded in untreated control plants in either the 1st and 2nd cuts.

4. Discussion

Around the world, iron deficiency (FED) is a significant issue that may have the desired effect on plant productivity in alkaline and calcareous soil. As a result, FED may be overcome via Fe-enriching methods, which involved conventional (sulphate or chelated) and nano-compounds supplementation. According to the results of the present investigation, foliar application of Fe-sources modifies the composition of EO, phytopharmaceuticals, and RSG-plant growth. It was also noted that the use of nano-sources specifically designed for humic acid Fe-NPs-HA offered the highest values of all examined attributes and enhanced the composition and quality of EO. Kah et al. [40] conveyed that nanofertilizers application had up to 30% more effective than traditional products. The peculiar characteristics of nano-particles, i.e., their large surface area, quick mass allocation, small size, high purity, and stability may be the cause of this observation [41]. In addition to accelerating enzymatic activities, nanoparticles also have the ability to reduce the accumulation of reactive oxygen species and oxidative damage that is improved plant development [23]. Moreover, it is attributed to their functions in modifying gene expression linked to several plant metabolic pathways [42].
Compared to untreated control plants, plant growth was dramatically boosted by the application of Fe-sources. These results were supported by previous investigations [8,18,24]. In this regard, the performance, root growth, and leaf count of sweet basil were all enhanced by the application of Fe3O4-NPs (1, 2, and 3 mg L−1) concentration [43]. Additionally, ryegrass and pumpkin showed improved root elongation with Fe supplementation [44]. Similar findings indicating the improved influence of Fe3O4 NPs on a shoot and root elongation were gathered by Zahra et al. [45]. The improvement of photosynthetic processes and nucleic acid assimilation, which is reflected in an increase in photoassimilates needed for cell division and enlargement and improved plant development, may be the cause of Fe-sources’ beneficial effects on plant growth [8,18,46].
It has been demonstrated that the use of Fe-sources significantly increased RSG-EO yield. Additionally, in both cuts during the first and second seasons, Nano-Fe in particular with HA (10 mg L−1) was the most successful treatment (Figure 2). Previous studies have also observed an increase in EO caused by the use of Fe-sources [7,47]. On sweet marjoram, El-Khateeb et al. [8] discovered that applying Fe-NPs boosted EO% and EO production. According to Nejad et al. [25], applying Fe-sources significantly raised EO% when compared to untreated RSG plants. The generation of carbohydrates and the buildup of plant EO were positively correlated [48]. According to the results of the current study, foliar application of Fe-sources led to a greater accumulation of total carbohydrates in the herb than the control (Table 8). As a result, FeSO4 application enhanced the content of total carbohydrates in coriander plants, according to Abou-Sreea et al. [7]. Fe-NPs foliar treatments considerably boosted the photosynthetic rate and chemical contents (carbohydrate, flavonoids, crude protein, total fatty acids, IAA), as well as oil yield, according to Abdel Wahab and Taha [49]. Additionally, El-Khateeb et al. [8] demonstrate that the total carbohydrates concentration in plant shoots of sweet marjoram treated with Fe-NPs was markedly elevated.
Essential oils, as a secondary metabolite, are highly complex mixtures of volatile compounds. Fe-sources applications affected not only EO yield but also EO constituents. In the present study, 11 constituents were identified in RSG-EO and the main components were citronellol, geraniol, and eugenol (Table 4 and Table 5). A widespread study was done on the constituents of RSG-EO, which distinguished considerable variations in their constituents worldwide. In this regard, Sharopov et al. [50] in Tajikistan identified 95.1% of RSG-EO constituents, including 79 components including citronellol (37.5%), geraniol (6.0%), caryophyllene oxide (3.7%), menthone (3.1%), linalool (3.0%), β-bourbonene (2.7%), isomenthone (2.1%), and geranylformate (2.0%).
Citronellol (C), geraniol (G), and their esters are the prime components in RSG-EO as per the prerequisites of perfumery productions [1]. The C/G is the main aspect that regulates the standard of RSG-EO for fragrance manufacturing [51]. Commonly, C/G proportion of 1:1–3:1 is satisfactory; nonetheless, the best ratio is 1:1 [1,52]. Oil of C/G ratio of over 3:1 is deliberated to be of deprived quality for fragrance manufacturing nonetheless still, it can be used for the manufacture of creams, toiletries, and fragrance-based objects at a lesser price [53,54]. The variance in the C/G ratio is probably associated with environmental factors at the harvesting, which eventually influences the assimilation of citronellol and geraniol. It is described that citronellol concentrations were greater in the warm season relative to the winter season [55].
The data herein revealed that the application of Fe sources significantly raised chlorophyll above untreated plants. In line with the current results, several researchers recognized that the application of Fe-NPs [24]; Fe-sulphate [18], EDDHA [18], and EDTA [56] increased leaves chlorophyll concentration over untreated plants. The encouragement roles of Fe on chlorophyll accumulation resulted from regulating Fe, Mg, and N uptake and increase Fe availability (Table 7), as well as regulate Chl assimilation gene expression [57], stimulation chlorophyll assimilation pathways [58] and encouraging the transformation of Mg-Proto to Pchlide and consequently Chl a and b. Moreover, Fe-sources application interferes Chl degradation as indicated in the present study (Table 6), by Pheo production and avoids the change of Mg-prototp Pchlide [59], as well as hastein ALA assimilation [60] due to declining Mg-proto and proto accumulation. As indicated previously, Fe-NPs were superior to other Fe sources in increasing chlorophyll concentration due to: (1) accelerating a dramatic upregulation of photosystem marker genes [61,62] formation of a complex with phytoferritin (leaves iron-binding protein), leading to greater involvement in chlorophyll assimilation [63]; (2) Improving thylakoid and chloroplast metabolic pathways that sequentially rise photosynthetic activities and lessening of chloroplast ROS [58,64].
The most recent results showed that spraying with Fe sources significantly increases the levels of N, P, K, Fe, Mn, and Zn in plant shoots as compared to untreated plants. The findings of El-Sonbaty [24] for Fe-NPs, Abou-Sreea et al. [7] for FeSO4, Erdale [65] for EDTA, and Tavallali [66] for EDDHA were in agreement with these results. In this regard, Gutierrez-Ruelas et al. [18] found that in green bean, the application of Fe sources (Fe-NPs, FeSO4, EDDHA) increased plant Fe concentration. Likewise, 0.2% Fe-EDDHA application amplified Chl a and Chl b and induced a marginal rise in the plant tissue N content [67]. Moreover, El-Sonbaty [24] found that spraying onion plants with Fe-NPs significantly increased N, P, and K content in plant organs over control plants. The role of Fe in increasing nutrient concentration and uptake may be due to increased energy availability and increased deactivated absorption of anions in root cells that increased absorption of cations as potassium [68]. Additionally, the increase in N in plant tissues by Fe sources (Fe-NPs, FeSO4, EDDHA) application may result from the role of Fe in the enhancement of nitrate reductase activity which is increased N uptake and accumulation [18].
Currently, the supplementation of Fe-sources improved phytopharmaceutical accumulation in plant shoots, which was in accord with previous research [25,66]. Numerous phytopharmaceuticales’ assembly was documented to be increased by elicitors including Fe [69,70]. The mechanism of elicitation by Fe, was, nonetheless, diverse in different herbs, and in the majority, an ‘elicitor–receptor’ complex was formed and a massive range of physio-biochemical responses was demonstrated [71]. The existing data have ascertained that Fe encouraged the extra accretion of phenolic in an RSG shoot. This might be because producing signal transduction systems and activating the gene for phenyl aminolyase (PAL), a secondary metabolic pathway, speed up the assimilation of phenols. The most important bioactive molecule with a reliable antioxidant has been determined to be phenolic chemicals. They have received more attention recently since they have been shown to be more effective than ascorbic acid, tocopherol, and carotenoid [72,73]. According to earlier studies [74,75,76], they have a variety of biological functions, including anti-inflammatory, antioxidant, antiviral, anticarcinogenic, anti-oxidant, antispasmodic, and depressive effects. Epidemiology surveys have discovered that a substantial nutritional intake of flavonoids and phenolics is coupled with lesser rates of cancer incidence [72]. The antioxidant aptitudes of phenolic compounds are mediated by numerous approaches [77]: (1) abolish ROS/reactive nitrogen species (RNS); (2) defeat ROS/RNS assembly by hindering numerous enzymes or chelating ions occupied in ROS; (3) regulate antioxidant capacity. Like total soluble phenolic, flavonoids establish a widespread secondary metabolite with polyphenolic structures and play an imperative function in shielding biological systems alongside oxidation processes [78]. In humans, flavonoids can impede aldose reductase and are occupied in diabetic difficulties i.e., neuropathy, heart disease, and retinopathy as well as attended as antioxidant compounds that lessen the hazard of cancers [79].

5. Conclusions

In the context of sustainable agriculture, prevailing and low-cost, using pioneering nanotechnology in agriculture is considered one of the encouraging attitudes for improving plant productivity. The current outcomes display a solid confirmation of the high effectiveness of nano fertilizer on plant productivity and product quality over conventional Fe-sources. The study recommended that since Fe NPs with humic acid are naturally non-toxic, they have been utilized as Fe-enriching fertilizers to replenish Fe levels in plants, demonstrating the significance of using Fe NPs for commercial purposes.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/agronomy12092164/s1, Table S1: Mean of monthly climatic data of the experimental site throughout the experimental seasons.

Author Contributions

Conceptualization, A.E.E.-S., S.F. and S.M.A.E.-G.; methodology, A.E.E.-S., S.F., E.F.A., H.M.A.-Y., A.A.S.A.-K. and S.M.A.E.-G.; software, S.F.; validation, A.E.E.-S., S.F., E.F.A., A.A.S.A.-K. and S.M.A.E.-G.; formal analysis, S.F.; investigation, A.E.E.-S., S.F. and S.M.A.E.-G.; resources, A.E.E.-S., S.F., E.F.A., H.M.A.-Y., A.A.S.A.-K. and S.M.A.E.-G.; data curation, A.E.E.-S., S.F. H.M.A.-Y., A.A.S.A.-K. and S.M.A.E.-G.; writing—original draft preparation, A.E.E.-S. and S.M.A.E.-G.; writing—review and editing, S.F., E.F.A. and H.M.A.-Y.; visualization, A.E.E.-S., S.F., E.F.A., H.M.A.-Y., A.A.S.A.-K. and S.M.A.E.-G.; supervision, A.E.E.-S., S.F. and S.M.A.E.-G.; project administration, S.F., E.F.A., H.M.A.-Y. and A.A.S.A.-K.; funding acquisition, A.E.E.-S., S.F., E.F.A., H.M.A.-Y., A.A.S.A.-K. and S.M.A.E.-G. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Taif University Researchers Supporting Project, grant number TURSP-2020/199.

Data Availability Statement

Not applicable.

Acknowledgments

The authors express their gratitude to Mansoura University, and Agricultural Research Center, Egypt, for supporting our manuscript. The authors are also thankful to Taif University Researchers Supporting Project number (TURSP-2020/199), Taif University, Saudi Arabia, for the financial support and research facilities.

Conflicts of Interest

The authors declare no conflict of interest.

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Agronomy 12 02164 g001 550
Figure 1. TEM imaging of the prepared magnetite nanoparticles revealed spherical shape of particles, with an average size of 9–14 nm.
Figure 1. TEM imaging of the prepared magnetite nanoparticles revealed spherical shape of particles, with an average size of 9–14 nm.
Agronomy 12 02164 g001
Agronomy 12 02164 g002 550
Figure 2. Effect of iron (nano, sulfate, and chelated) foliar spray on EO oil yield of Sweet Scented geranium during experimental seasons. (A) EO % in two cuts of the 1st season, (B) EO % in two cuts of the 2nd season, (C) EO yield (mL/plant) in two cuts of the 1st season, (D) EO yield (mL/plant) in two cuts of the 2nd season, (E) EO yield (L/fed.) in two cuts of the 1st season, (F) EO yield (L/fed.) in two cuts of the 2nd season. Means of three replicates are presented with ± SE. For each parameter in the year, different letters within the column show significant differences between the treatments and control according to Tukey’s HSD test at p ˂ 0.05. T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, and T11 are control, 5 mg L−1 Fe-NPs, 10 mg L−1 Fe-NPs, 5 mg L−1 Fe-NPs HA, 10 mg L−1 Fe-NPs HA, 100 mg L−1 FeSO4, 200 mg L−1 FeSO4, 100 mg L−1 EDDHA, 200 mg L−1 EDDHA, 100 mg L−1 EDTA, and 200 mg L−1 EDTA, respectively.
Figure 2. Effect of iron (nano, sulfate, and chelated) foliar spray on EO oil yield of Sweet Scented geranium during experimental seasons. (A) EO % in two cuts of the 1st season, (B) EO % in two cuts of the 2nd season, (C) EO yield (mL/plant) in two cuts of the 1st season, (D) EO yield (mL/plant) in two cuts of the 2nd season, (E) EO yield (L/fed.) in two cuts of the 1st season, (F) EO yield (L/fed.) in two cuts of the 2nd season. Means of three replicates are presented with ± SE. For each parameter in the year, different letters within the column show significant differences between the treatments and control according to Tukey’s HSD test at p ˂ 0.05. T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, and T11 are control, 5 mg L−1 Fe-NPs, 10 mg L−1 Fe-NPs, 5 mg L−1 Fe-NPs HA, 10 mg L−1 Fe-NPs HA, 100 mg L−1 FeSO4, 200 mg L−1 FeSO4, 100 mg L−1 EDDHA, 200 mg L−1 EDDHA, 100 mg L−1 EDTA, and 200 mg L−1 EDTA, respectively.
Agronomy 12 02164 g002
Table
Table 1. Physical and chemical analyses of the experimental soil in two seasons.
Table 1. Physical and chemical analyses of the experimental soil in two seasons.
Soil PropertiesValues
1st Season2nd Season
Particle size distribution (%)Sand (%)21.0021.19
Silt (%)35.9234.82
Clay (%)43.0844.08
Some physical and chemical trialsElectrical conductivity (dSm−1)4.0704.060
pH (soil paste)7.6307.700
Calcium carbonate (%)3.7303.810
Nitrogen (mg kg−1 soil)20.32 21.03
Phosphorus (mg kg−1 soil)16.72 17.63
Cations (meq 100 g−1 soil)Calcium2.0004.000
Magnesium11.3312.12
Sodium2.7402.720
potassium2.0602.090
Anions (meq 100 g−1 soil)Carbonate0.0000.000
Bicarbonate0.3700.360
Chloride4.6904.650
sulfate5.6305.690
Table
Table 2. The experimental treatments and their identifications.
Table 2. The experimental treatments and their identifications.
No.TreatmentsAbbreviation
1Control (Spraying with tap water)T1
2Spraying with 5 mg L−1 Fe-NPsT2
3Spraying with 10 mg L−1 Fe-NPsT3
4Spraying with 5 mg L−1 Fe-NPs with humic (Fe-NPs-HA)T4
5Spraying with 10 mg L−1 Fe-NPs with humic (Fe-NPs-HA)T5
6Spraying with 100 mg L−1 ferric sulfateT6
7Spraying with 200 mg L−1 ferric sulfateT7
8Spraying with 100 mg L−1 EDDHAT8
9Spraying with 200 mg L−1 EDDHAT9
10Spraying with 100 mg L−1 EDTAT10
11Spraying with 200 mg L−1 EDTAT11
Table
Table 3. Effect of iron (nano, sulfate, and chelated) foliar spray on some vegetative growth parameters of Sweet Scented geranium during the 2018 and 2019 experimental seasons. Means of three replicates are presented with ± SE.
Table 3. Effect of iron (nano, sulfate, and chelated) foliar spray on some vegetative growth parameters of Sweet Scented geranium during the 2018 and 2019 experimental seasons. Means of three replicates are presented with ± SE.
First Season
TreatmentsCut 1Cut 2
Plant Height (cm)Branches No/PlantShoot Fresh Weight (g)Shoot Dry Weight (g)Plant Height (cm)Branches No/PlantShoot Fresh Weight (g)Shoot Dry Weight (g)
T134.6 ± 0.88 h13.0 ± 0.57 h617.6 ± 5.48 k108.5 ± 0.94 k43.3 ± 0.88 h18.0 ± 0.57 g838.3 ± 6.64 k164.0 ± 1.36 k
T266.3 ± 0.88 c30.6 ± 0.88 c1179 ± 8.50 d238.5 ± 1.72 d75.6 ± 1.20 c43.0 ± 1.15 c1852 ± 7.53 d438.61.78 d
T371.3 ± 0.88 b33.3 ± 0.88 bc1261 ± 4.61 c258.1 ± 0.94 c81.0 ± 1.15 b46.0 ± 0.57 bc2024 ± 7.83 c483.6 ± 1.87 c
T475.0 ± 0.57 ab35.0 ± 0.57 ab1433 ± 8.14 b303.6 ± 1.72 b84.3 ± 1.20 ab48.0 ± 1.15 ab2262 ± 8.14 b545.5 ± 1.96 b
T578.3 ± 0.88 a38.0 ± 0.57 a1560 ± 6.35 a341.1 ± 1.39 a89.0 ± 1.15 a51.3 ± 0.88 a2469 ± 6.08 a616.0 ± 1.51 a
T642.6 ± 0.88 fg17.0 ± 0.57 fg719.3 ± 7.51 i125.2 ± 1.30 i49.6 ± 0.88 fg20.6 ± 0.88 fg1020 ± 7.83 i217.5 ± 1.67 i
T739.6 ± 0.88 g15.0 ± 0.57 gh665.0 ± 6.08 j116.5 ± 0.68 j45.6 ± 0.88 gh19.0 ± 0.57 fg965.0 ± 4.72 j198.5 ± 1.00 j
T846.3 ± 0.88 f20.0 ± 0.57 ef783.6 ± 6.93 h137.6 ± 1.21 gh53.6 ± 0.88 ef23.0 ± 0.57 f1123 ± 6.11 h243.2 ± 1.32 h
T951.3 ± 0.88 e23.0 ± 0.57 de834.3 ± 6.11 g148.3 ± 1.08 g58.3 ± 0.88 e28.6 ± 0.88 e1332 ± 11.4 g291.2 ± 2.49 g
T1057.6 ± 0.88 d24.0 ± 0.57 d928.3 ± 5.78 f174.1 ± 1.08 f65.60.88 d32.3 ± 0.88 de1483 ± 7.93 f336.2 ± 1.79 f
T1161.3 ± 0.88 d26.0 ± 0.57 d990.3 ± 4.33 e187.2 ± 0.81 e72.0 ± 1.15 c36.0 ± 0.57 d1597 ± 7.05 e365.8 ± 1.61 e
ANOVA p************************
Second season
TreatmentsCut 1Cut2
Plant Height (cm)Branches No/plantShoot fresh weight (g)Shoot dry weight (g)Plant Height (cm)Branches No/plantShoot fresh weight (g)Shoot dry weight (g)
T136.6 ± 0.88 h15.0 ± 0.57 f648.6 ± 5.23 k114.0 ± 0.90 k44.6 ± 0.88 g19.0 ± 0.57 f851.3 ± 4.94 k166.8 ± 1.00 k
T267.6 ± 0.88 c32.6 ± 0.88 b1192 ± 4.33 d241.4 ± 0.87 d77.0 ± 0.57 c44.6 ± 0.88 b1886 ± 6.93 d447.3 ± 1.64 d
T372.3 ± 0.88 b34.3 ± 0.88 ab1283 ± 3.60 c263.0 ± 0.73 c82.3 ± 0.88 b47.6 ± 0.88 ab2052 ± 6.38 c491.0 ± 1.52 c
T475.6 ± 0.88 b37.0 ± 1.15 ab1457 ± 3.84 b309.1 ± 0.812 b86.6 ± 0.88 ab50.0 ± 1.15 a2282 ± 6.08 b551.3 ± 1.46 b
T581.3 ± 0.88 a39.0 ± 1.15 a1583 ± 4.05 a346.6 ± 0.88 a91.0 ± 1.15 a51.6 ± 1.20 a2489 ± 6.42 a621.7 ± 1.60 a
T644.6 ± 0.88 fg18.6 ± 1.20 ef734.6 ± 4.91 e128.0 ± 0.85 i 52.6 ± 0.88 f23.0 ± 0.57 ef1055 ± 6.80 i225.2 ± 1.45 i
T741.6 ± 0.88 g16.0 ± 0.57 ef688.0 ± 3.78 j120.3 ± 0.66 j47.6 ± 0.88 g20.0 ± 0.57 f890.3 ± 4.97 j186.2 ± 1.06 j
T847.3 ± 0.88 f20.3 ± 1.20 de810.0 ± 4.35 h142.5 ± 0.76 h55.6 ± 0.88 f25.3 ± 0.88 e1154 ± 4.35 h250.1 ± 0.94 h
T952.3 ± 0.88 e24.0 ± 1.15 cd849.3 ± 6.11 g151.3 ± 1.09 g61.3 ± 0.88 e31.0 ± 1.15 d1377 ± 7.00 g301.4 ± 1.53 g
T1060.3 ± 0.88 d25.3 ± 0.88 c952.0 ± 5.50 f178.8 ± 1.03 f67.6 ± 0.88 d34.3 ± 0.88 cd1509 ± 5.50 f342.4 ± 1.24 f
T1163.3 ± 0.88 cd27.6 ± 0.88 c1019 ± 4.91 e193.0 ± 0.93 e72.6 ± 0.88 c37.6 ± 0.88 c1624 ± 6.35 e372.3 ± 1.45 e
ANOVA p************************
Levels of significance are represented by *** p ˂ 0.001. For each parameter in the year, different letters within the column show significant differences between the treatments and control according to Tukey’s HSD test at p ˂ 0.05. T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, and T11 are control, 5 mg L−1 Fe-NPs, 10 mg L−1 Fe-NPs, 5 mg L−1 Fe-NPs HA, 10 mg L−1 Fe-NPs HA, 100 mg L−1 FeSO4, 200 mg L−1 FeSO4, 100 mg L−1 EDDHA, 200 mg L−1 EDDHA, 100 mg L−1 EDTA, and 200 mg L−1 EDTA, respectively.
Table
Table 4. Effect of iron (nano, sulfate, and chelated) foliar spray on essential oil active constituent’s retention time (RT) and percentage (area %) of Sweet Scented geranium in the first cut during the 2019 experimental season. Means of three replicates are presented with ± SE.
Table 4. Effect of iron (nano, sulfate, and chelated) foliar spray on essential oil active constituent’s retention time (RT) and percentage (area %) of Sweet Scented geranium in the first cut during the 2019 experimental season. Means of three replicates are presented with ± SE.
Treatmentsα–PineneMyrceneIsomenthoneLinaloolCitronelyl
Formate		Geranyl
Formate		CitronelolGeraniolGeranyl
Butrate		Eugenolβ-
Caryophyllene		Unknown
Constituents		C/G Ratio
RTArea%RTArea%RTArea%RTArea%RTArea%RTArea%RTArea%RTArea%RTArea%RTArea%RTArea%Area%
T12.100.363.811.465.124.295.344.216.067.926.838.007.4821.438.2221.028.501.6610.5013.2311.432.4613.960.933
T22.030.353.720.825.013.995.255.985.935.916.705.337.3322.428.0719.098.359.2310.318.2610.954.2014.420.817
T32.180.543.890.735.205.995.415.216.128.756.877.787.5025.298.2323.798.501.7510.4810.5111.091.388.281.005
T41.800.533.451.044.716.604.958.015.629.116.377.046.9825.587.7123.057.981.159.906.2110.331.4910.191.107
T52.771.374.201.285.364.005.575.096.295.597.077.417.7124.938.4727.588.981.7010.7010.0111.302.253.480.814
T62.240.873.990.365.334.725.556.386.255.587.035.487.6318.298.4230.218.672.5710.698.6111.322.7514.180.621
T72.240.594.190.545.324.205.546.016.266.157.047.557.6419.158.4126.668.683.0710.7011.5611.335.019.510.678
T82.130.133.530.604.625.504.885.415.588.726.347.547.0022.537.7526.877.991.539.918.6710.522.589.920.882
T91.730.503.340.454.644.944.905.945.607.876.365.887.0220.547.8029.548.031.649.939.7910.501.9910.920.766
T102.060.303.830.125.163.365.416.036.157.096.939.147.5923.898.3727.738.872.3510.6110.8211.551.907.270.787
T112.050.723.490.195.124.905.366.556.065.436.846.177.4621.718.2536.888.740.4310.476.4711.081.439.120.624
T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, and T11 are control, 5 mg L−1 Fe-NPs, 10 mg L−1 Fe-NPs, 5 mg L−1 Fe-NPs HA, 10 mg L−1 Fe-NPs HA, 100 mg L−1 FeSO4, 200 mg L−1 FeSO4, 100 mg L−1 EDDHA, 200 mg L−1 EDDHA, 100 mg L−1 EDTA, and 200 mg L−1 EDTA, respectively.
Table
Table 5. Effect of iron (nano, sulfate, and chelated) foliar spray on essential oil active constituent’s retention time (RT) and percentage (area %) of Sweet Scented geranium in the second cut during the 2019 experimental season. Means of three replicates are presented with ± SE.
Table 5. Effect of iron (nano, sulfate, and chelated) foliar spray on essential oil active constituent’s retention time (RT) and percentage (area %) of Sweet Scented geranium in the second cut during the 2019 experimental season. Means of three replicates are presented with ± SE.
Treatmentsα–PineneMyrceneIsomenthoneLinaloolCitronelyl
Formate		Geranyl
Formate		CitronelolGeraniolGeranyl
Butrate		Eugenolβ-
Caryophyllene		Unknown
Constituents		C/G Ratio
RTArea
%		RTArea
%		RTArea
%		RTArea
%		RTArea
%		RTArea
%		RTArea
%		RTArea
%		RTArea
%		RTArea
%		RTArea
%		Area
%
T12.060.623.801.095.196.205.405.116.159.356.874.347.6335.558.3017.288.790.8510.528.3611.082.858.452.029
T22.110.483.880.775.226.665.446.316.168.756.916.277.5526.078.2824.418.541.8310.505.2511.110.7612.441.071
T32.050.383.750.354.934.335.1912.785.866.996.632.767.2728.938.0222.638.512.0210.225.2010.861.1712.461.307
T42.030.344.120.735.525.365.725.536.468.567.235.637.9234.468.6317.558.922.8110.959.6311.603.276.132.809
T52.271.314.071.225.485.595.673.476.448.537.203.197.9332.198.6214.068.912.1510.9710.2411.612.9215.132.098
T62.260.423.991.035.394.205.562.696.357.317.073.097.8632.948.5112.508.813.6110.8513.3311.432.4616.422.096
T72.350.324.080.955.424.535.583.336.378.517.043.557.8136.278.4714.968.752.5610.7211.4111.283.3010.312.125
T82.150.303.870.795.224.985.392.486.147.636.853.227.6134.508.2311.288.542.9510.5313.2311.444.2314.412.478
T92.160.683.881.315.215.715.403.096.127.696.863.187.5331.448.2115.288.512.1310.5012.2111.094.4812.81.896
T102.041.073.471.414.626.984.862.765.558.046.294.916.9636.977.6311.897.921.889.857.7810.802.4913.822.409
T112.170.523.810.435.104.515.303.876.027.696.734.507.4226.538.1422.788.392.6610.3110.6411.172.5613.311.142
T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, and T11 are control, 5 mg L−1 Fe-NPs, 10 mg L−1 Fe-NPs, 5 mg L−1 Fe-NPs HA, 10 mg L−1 Fe-NPs HA, 100 mg L−1 FeSO4, 200 mg L−1 FeSO4, 100 mg L−1 EDDHA, 200 mg L−1 EDDHA, 100 mg L−1 EDTA, and 200 mg L−1 EDTA, respectively.
Table
Table 6. Effect of iron (nano, sulfate, and chelated) foliar spray on chlorophyll of Sweet Scented Geranium in the first and second cuts during the 2019 experimental season. Means of three replicates are presented with ± SE.
Table 6. Effect of iron (nano, sulfate, and chelated) foliar spray on chlorophyll of Sweet Scented Geranium in the first and second cuts during the 2019 experimental season. Means of three replicates are presented with ± SE.
TreatmentsFirst Cut
Total Chlorophyll
(mg g−1 FW)		Total Carotenoids
(mg g−1 FW)		Chl A
(mg g−1 FW)		Pheo A
(mg g−1 FW)		Chl a/ChildChl b/ChildMg Proto
(μg g−1 FW)		Proto
(μg g−1 FW)		Pchilde
(mg g−1 FW)
T10.862 ± 0.031 g0.190 ± 0.006 f0.530 ± 0.079 e0.317 ± 0.014 b0.940 ± 0.023 f0.895 ± 0.036 c0.274 ± 0.015 a0.461 ± 0.004 a0.977 ± 0.005 a
T21.679 ± 0.038 cd0.313 ± 0.010 a–c1.148 ± 0.027 ab0.476 ± 0.034 a1.926 ± 0.062 c1.677 ± 0.066 b0.209 ± 0.001 bc0.293 ± 0.001 f0.542 ± 0.033 e
T31.810 ± 0.052 bc0.317 ± 0.008 ab1.204 ± 0.022 a0.481 ± 0.004 a2.281 ± 0.020 b2.226 ± 0.092 a0.188 ± 0.002 cd0.265 ± 0.001 g0.538 ± 0.009 e
T41.955 ± 0.055 ab0.319 ± 0.008 ab1.217 ± 0.075 a0.508 ± 0.021 a2.428 ± 0.039 ab2.328 ± 0.127 a0.175 ± 0.002 cd0.244 ± 0.001 h0.530 ± 0.008 e
T52.038 ± 0.008 a0.323 ± 0.001 a1.248 ± 0.091 a0.538 ± 0.016 a2.577 ± 0.014 a2.355 ± 0.068 a0.160 ± 0.001 e0.226 ± 0.001 i0.503 ± 0.018 e
T61.116 ± 0.008 f0.237 ± 0.031 d–f0.830 ± 0.016 cd0.436 ± 0.035 ab0.987 ± 0.026 ef0.923 ± 0.041 c0.223 ± 0.002 b0.314 ± 0.001 c0.785 ± 0.027 bc
T70.957 ± 0.005 g0.214 ± 0.005 ef0.767 ± 0.010 de0.429 ± 0.035 ab0.975 ± 0.035 f0.878 ± 0.082 c0.253 ± 0.002 a0.354 ± 0.001 b0.815 ± 0.035 b
T81.256 ± 0.025 f0.255 ± 0.011 c–e0.892 ± 0.053 b–d0.435 ± 0.017 ab1.157 ± 0.037 e1.028 ± 0.045 c0.217 ± 0.001 b0.303 ± 0.001 de0.686 ± 0.028 cd
T91.261 ± 0.015 f0.263 ± 0.004 be0.936 ± 0.010 b–d0.453 ± 0.032 a1.698 ± 0.037 d1.544 ± 0.046 b0.216 ± 0.002 b0.305 ± 0.001 d0.580 ± 0.036 de
T101.448 ± 0.003 e0.288 ± 0.005 a–d1.017 ± 0.055 a–d0.476 ± 0.018 a1.725 ± 0.028 d1.552 ± 0.051 b0.213 ± 0.002 bc0.299 ± 0.001 d–f0.562 ± 0.011 e
T111.562 ± 0.007 de0.298 ± 0.004 a–c1.086 ± 0.032 a–d0.469 ± 0.030 a1.773 ± 0.024 cd1.618 ± 0.054 b0.211 ± 0.002 bc0.296 ± 0.001 ef0.556 ± 0.007 e
ANOVA p***************************
Second Cut
TreatmentsTotal Chlorophyll
(mg g−1 FW)		Total Carotenoids
(mg g−1 FW)		Chl A
(mg g−1 FW)		Pheo A
(mg g−1 FW)		Chl a/ChildChl b/ChildMg Proto
(μg g−1 FW)		Proto
(μg g−1 FW)		Pchilde
(mg g−1 FW)
T10.883 ± 0.011 h0.144 ± 0.002 g0.430 ± 0.000 f0.333 ± 0.011 f0.706 ± 0.019 g0.645 ± 0.026 h0.298 ± 0.002 a0.415 ± 0.001 a0.913 ± 0.019 a
T21.650 ± 0.008 c0.263 ± 0.004 ab1.054 ± 0.053 ab0.561 ± 0.026 bc2.213 ± 0.065 c2.032 ± 0.085 cd0.198 ± 0.002 d0.278 ± 0.001 e0.567 ± 0.018 c
T31.813 ± 0.030 b0.274 ± 0.004 ab1.148 ± 0.043 a0.573 ± 0.025 ab2.404 ± 0.057 bc2.237 ± 0.106 bc0.193 ± 0.001 d0.269 ± 0.001 f0.562 ± 0.011 c
T41.802 ± 0.010 b0.283 ± 0.001 a1.167 ± 0.022 a0.676 ± 0.021 a2.526 ± 0.002 b2.400 ± 0.054 b0.149 ± 0.001 e0.209 ± 0.001 g0.426 ± 0.017 d
T51.933 ± 0.010 a0.286 ± 0.001 a1.210 ± 0.068 a0.676 ± 0.018 a3.671 ± 0.069 a3.399 ± 0.126 a0.100 ± 0.001 f0.140 ± 0.001 h0.424 ± 0.004 d
T61.132 ± 0.024 g0.179 ± 0.005 f0.674 ± 0.032 e0.444 ± 0.033 e1.087 ± 0.038 ef1.012 ± 0.052 fg0.248 ± 0.003 b0.349 ± 0.001 b0.749 ± 0.009 b
T71.096 ± 0.013 g0.163 ± 0.012 fg0.667 ± 0.016 e0.437 ± 0.018 ef0.917 ± 0.022 fg0.845 ± 0.037 gh0.250 ± 0.002 b0.348 ± 0.001 b0.887 ± 0.004 a
T81.272 ± 0.012 f0.193 ± 0.001 ef0.767 ± 0.010 de0.455 ± 0.009 de1.142 ± 0.034 ef1.032 ± 0.037 fg0.248 ± 0.002 b0.346 ± 0.001 b0.624 ± 0.015 c
T91.398 ± 0.040 e0.210 ± 0.008 de0.861 ± 0.043 cd0.458 ± 0.024 c–e1.302 ± 0.021 e1.214 ± 0.039 ef0.243 ± 0.001 b0.338 ± 0.001 c0.606 ± 0.005 c
T101.495 ± 0.023 de0.230 ± 0.004 cd0.955 ± 0.010 bc0.556 ± 0.018 b–d1.560 ± 0.046 d1.399 ± 0.060 e0.219 ± 0.001 c0.309 ± 0.001 d0.575 ± 0.005 c
T111.539 ± 0.006 d0.249 ± 0.007 bc1.086 ± 0.032 ab0.569 ± 0.002 b2.186 ± 0.067 c1.852 ± 0.071 d0.202 ± 0.002 d0.280 ± 0.001 e0.573 ± 0.014 c
ANOVA p************************ ***
Levels of significance are represented by *** p ˂ 0.001. For each parameter in the year, different letters within the column show significant differences between the treatments and control according to Tukey’s HSD test at p ˂ 0.05. T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, and T11 are control, 5 mg L−1 Fe-NPs, 10 mg L−1 Fe-NPs, 5 mg L−1 Fe-NPs HA, 10 mg L−1 Fe-NPs HA, 100 mg L−1 FeSO4, 200 mg L−1 FeSO4, 100 mg L−1 EDDHA, 200 mg L−1 EDDHA, 100 mg L−1 EDTA, and 200 mg L−1 EDTA, respectively.
Table
Table 7. Effect of iron (nano, sulfate, and chelated) foliar spray on nutrients content of Sweet Scented Geranium in the first and second cut during the 2019 experimental season. Means of three replicates are presented with ± SE.
Table 7. Effect of iron (nano, sulfate, and chelated) foliar spray on nutrients content of Sweet Scented Geranium in the first and second cut during the 2019 experimental season. Means of three replicates are presented with ± SE.
TreatmentsCut 1Cut2
N%P%K%Fe
(mg L−1)		Mn
(mg L−1)		Zn
(mg L−1)		N%P%K%Fe
(mg L−1)		Mn
(mg L−1)		Zn
(mg L−1)
T11.98 ± 0.026 e0.150 ± 0.001 g1.13 ± 0.014 g144 ± 0.352 k21.7 ± 0.161 k21.0 ± 0.282 k2.35 ± 0.014 f0.150 ± 0.001 g1.59 ± 0.011 e152 ± 1.00 k17.5 ± 0.178 i35.6 ± 0.294 i
T22.83 ± 0.017 b0.179 ± 0.001 c1.65 ± 0.017 c275 ± 0.889 d43.0 ± 0.280 d41.7 ± 0.115 d3.37 ± 0.011 b0.179 ± 0.001 c2.28 ± 0.015 b451 ± 0.542 d25.4 ± 0.121 d52.3 ± 0.161 d
T32.87 ± 0.017 b0.180 ± 0.001 c1.72 ± 0.014 b400 ± 1.39 c48.5 ± 0.060 c47.1 ± 0.282 c3.42 ± 0.014 b0.180 ± 0.001 c2.43 ± 0.011 a458 ± 0.069 c28.6 ± 0.103 c58.9 ± 0.219 c
T42.89 ± 0.026 b0.205 ± 0.001 b2.03 ± 0.012 a411 ± 0.987 b77.5 ± 0.092 b75.3 ± 0.057 b3.43 ± 0.014 b0.205 ± 0.001 b2.44 ± 0.020 a524 ± 0.744 b36.7 ± 0.127 b75.9 ± 0.173 b
T53.33 ± 0.014 a0.222 ± 0.001 a2.07 ± 0.014 a443 ± 1.40 a89.7 ± 0.083 a87.0 ± 0.271 a3.97 ± 0.017 a0.222 ± 0.001 a2.45 ± 0.014 a534 ± 0.600 a43.0 ± 0.196 a89.7 ± 0.132 a
T62.18 ± 0.020 d0.168 ± 0.001 e1.22 ± 0.014 f184 ± 0.606 i26.0 ± 0.190 i25.3 ± 0.127 i2.60 ± 0.011 de0.168 ± 0.001 e2.04 ± 0.014 c176 ± 0.519 i19.4 ± 0.063 h39.6 ± 0.132 h
T72.14 ± 0.017 d0.161 ± 0.001 f1.19 ± 0.011 fg157 ± 0.467 j23.2 ± 0.176 j22.5 ± 0.161 j2.54 ± 0.020 e0.161 ± 0.001 f1.78 ± 0.018 d161 ± 0.404 j17.8 ± 0.109 i36.6 ± 0.225 i
T82.20 ± 0.023 d0.172 ± 0.001 de1.23 ± 0.011 f191 ± 0.623 h28.2 ± 0.242 h27.4 ± 0.167 h2.62 ± 0.014 de0.172 ± 0.001 de2.06 ± 0.020 c198 ± 0.877 h20.3 ± 0.161 g41.7 ± 0.305 g
T92.23 ± 0.017 d0.173 ± 0.001 de1.24 ± 0.011 f222 ± 0.207 g30.6 ± 0.383 g29.7 ± 0.063 g2.64 ± 0.020 d0.173 ± 0.001 de2.08 ± 0.068 c229 ± 0.831 g21.9 ± 0.167 f45.2 ± 0.254 f
T102.43 ± 0.014 c0.177 ± 0.001 cd1.35 ± 0.014 e253 ± 0.900 f33.5 ± 0.228 f32.5 ± 0.242 f2.90 ± 0.017 c0.177 ± 0.001 cd2.11 ± 0.014 c388 ± 0.906 f24.5 ± 0.225 e50.6 ± 0.155 e
T112.49 ± 0.023 c0.178 ± 0.001 c1.49 ± 0.012 d268 ± 1.03 e40.5 ± 0.167 e39.3 ± 0.150 e2.97 ± 0.020 c0.178 ± 0.001 c2.26 ± 0.014 b444 ± 0.456 e24.7 ± 0.103 de50.8 ± 0.069 e
ANOVA p************************************
Levels of significance are represented by *** p ˂ 0.001. For each parameter in the year, different letters within the column show significant differences between the treatments and control according to Tukey’s HSD test at p ˂ 0.05. T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, and T11 are control, 5 mg L−1 Fe-NPs, 10 mg L−1 Fe-NPs, 5 mg L−1 Fe-NPs HA, 10 mg L−1 Fe-NPs HA, 100 mg L−1 FeSO4, 200 mg L−1 FeSO4, 100 mg L−1 EDDHA, 200 mg L−1 EDDHA, 100 mg L−1 EDTA, and 200 mg L−1 EDTA, respectively.
Table
Table 8. Effect of iron (nano, sulfate, and chelated) foliar spray on carbohydrates and phytopharmaceuticals of Rose Scented Geranium in the first and second cut during the second season. Means of three replicates are presented with ± SE.
Table 8. Effect of iron (nano, sulfate, and chelated) foliar spray on carbohydrates and phytopharmaceuticals of Rose Scented Geranium in the first and second cut during the second season. Means of three replicates are presented with ± SE.
TreatmentsCarbohydrates
(mg g−1 FW)		Phenol
(mg gallic acid g−1 DW)		Flavonoids
(mg quercetine g−1 DW)		Anthocyanin
(mg 100 g−1 FW)
Cut 1Cut 2Cut 1Cut 2Cut 1Cut 2Cut 1Cut 2
T13.041 ± 0.439 b3.295 ± 0.124 e8.084 ± 0.157 g10.91 ± 0.199 d0.989 ± 0.007 d0.998 ± 0.008 g2.156 ± 0.028 c2.167 ± 0.012 f
T25.091 ± 0.143 a5.143 ± 0.081 a–c12.99 ± 0.199 a–c13.82 ± 0.124 ab2.690 ± 0.067 a2.719 ± 0.054 b–d3.815 ± 0.047 ab3.959 ± 0.009 b–d
T35.424 ± 0.097 a5.532 ± 0.016 ab13.73 ± 0.264 ab13.98 ± 0.356 ab2.690 ± 0.044 a2.787 ± 0.040 bc4.114 ± 0.053 a4.339 ± 0.049 a–c
T45.557 ± 0.025 a5.604 ± 0.047 ab13.98 ± 0.242 a14.43 ± 0.227 a2.736 ± 0.033 a2.851 ± 0.041 ab4.146 ± 0.024 a4.828 ± 0.115 ab
T55.965 ± 0.416 a5.971 ± 0.020 a14.27 ± 0.264 a14.83 ± 0.530 a2.762 ± 0.047 a3.007 ± 0.012 a4.238 ± 0.224 a5.183 ± 0.023 a
T64.369 ± 0.136 ab4.104 ± 0.261 de10.95 ± 0.318 ef12.61 ± 0.264 bc1.658 ± 0.073 b2.478 ± 0.022 e3.318 ± 0.113 b2.954 ± 0.026 ef
T74.315 ± 0.063 ab3.978 ± 0.060 de10.37 ± 0.446 f11.89 ± 0.448 cd1.425 ± 0.042 c1.429 ± 0.040 f3.250 ± 0.018 b2.786 ± 0.032 ef
T84.529 ± 0.079 ab4.184 ± 0.052 c–e11.31 ± 0.246 d–f12.70 ± 0.338 bc1.840 ± 0.038 b2.559 ± 0.023 de3.361 ± 0.292 b3.249 ± 0.079 de
T94.645 ± 0.929 ab4.441 ± 0.351 cd11.60 ± 0.369 d–f13.33 ± 0.136 a–c2.550 ± 0.007 a2.584 ± 0.011 de3.557 ± 0.248 ab3.475 ± 0.263 c–e
T104.749 ± 0.073 ab4.737 ± 0.356 b–d11.96 ± 0.102 c–e13.66 ± 0.408 ab2.593 ± 0.025 a2.669 ± 0.042 cd3.674 ± 0.008 ab3.462 ± 0.044 c–e
T114.883 ± 0.033 a4.785 ± 0.323 b–d12.59 ± 0.213 b–d13.69 ± 0.220 ab2.609 ± 0.015 a2.703 ± 0.038 b–d3.704 ± 0.063 ab3.655 ± 0.539 c–e
ANOVA p*********************
Levels of significance are represented by *** p ˂ 0.001. For each parameter in the year, different letters within the column show significant differences between the treatments and control according to Tukey’s HSD test at p ˂ 0.05. T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, and T11 are control, 5 mg L−1 Fe-NPs, 10 mg L−1 Fe-NPs, 5 mg L−1 Fe-NPs HA, 10 mg L−1 Fe-NPs HA, 100 mg L−1 FeSO4, 200 mg L−1 FeSO4, 100 mg L−1 EDDHA, 200 mg L−1 EDDHA, 100 mg L−1 EDTA, and 200 mg L−1 EDTA, respectively.
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El-Sonbaty, A.E.; Farouk, S.; Al-Yasi, H.M.; Ali, E.F.; Abdel-Kader, A.A.S.; El-Gamal, S.M.A. Enhancement of Rose Scented Geranium Plant Growth, Secondary Metabolites, and Essential Oil Components through Foliar Applications of Iron (Nano, Sulfur and Chelate) in Alkaline Soils. Agronomy 2022, 12, 2164. https://doi.org/10.3390/agronomy12092164

AMA Style

El-Sonbaty AE, Farouk S, Al-Yasi HM, Ali EF, Abdel-Kader AAS, El-Gamal SMA. Enhancement of Rose Scented Geranium Plant Growth, Secondary Metabolites, and Essential Oil Components through Foliar Applications of Iron (Nano, Sulfur and Chelate) in Alkaline Soils. Agronomy. 2022; 12(9):2164. https://doi.org/10.3390/agronomy12092164

Chicago/Turabian Style

El-Sonbaty, Amany E., Saad Farouk, Hatim M. Al-Yasi, Esmat F. Ali, Atef A. S. Abdel-Kader, and Seham M. A. El-Gamal. 2022. "Enhancement of Rose Scented Geranium Plant Growth, Secondary Metabolites, and Essential Oil Components through Foliar Applications of Iron (Nano, Sulfur and Chelate) in Alkaline Soils" Agronomy 12, no. 9: 2164. https://doi.org/10.3390/agronomy12092164

APA Style

El-Sonbaty, A. E., Farouk, S., Al-Yasi, H. M., Ali, E. F., Abdel-Kader, A. A. S., & El-Gamal, S. M. A. (2022). Enhancement of Rose Scented Geranium Plant Growth, Secondary Metabolites, and Essential Oil Components through Foliar Applications of Iron (Nano, Sulfur and Chelate) in Alkaline Soils. Agronomy, 12(9), 2164. https://doi.org/10.3390/agronomy12092164

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