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Article

Enhancing Salinity Tolerance of Fig Transplants Cv. Conadria via Exogenous Application of Sodium Nitroprusside

Pomology Department, Faculty of Agriculture, Cairo University, Giza 12613, Egypt
*
Author to whom correspondence should be addressed.
Stresses 2025, 5(2), 36; https://doi.org/10.3390/stresses5020036
Submission received: 22 March 2025 / Revised: 10 May 2025 / Accepted: 13 May 2025 / Published: 3 June 2025
(This article belongs to the Section Plant and Photoautotrophic Stresses)

Abstract

:
The present research was designed to assess the potential effect of SNP to alleviate salinity stress injury in fig transplants cv. Conadria. One-year-old transplants irrigated with saline water (6.25 ds/m) were treated with sodium nitroprusside (SNP) at four concentrations (0, 50, 100 and 200 µM); untreated transplants exposed to salt stress represent the positive control, while the non-stressed transplants represent the negative control. Salt stress showed a considerable increase in lipid peroxidation, proline, sodium, chloride content and antioxidant enzyme activity and reduced vegetative growth parameters, photosynthetic pigments, phenolic content and K/Na ratio. SNP reduced salt stress injury in fig transplants through maintaining higher values of growth parameters and photosynthetic pigment content, reducing sodium accumulation and maintaining the integrity of cell membrane lipids. SNP-treated transplants accumulated higher amounts of potassium ions and a higher K/Na ratio. SNP at 100 µM was the most efficient treatment in enhancing the response to salt stress. Overall, the results show that SNP application is a promising practice for alleviating salt stress on fig transplants.

1. Introduction

The common fig (Ficus carica L.) is a deciduous shrub belonging to the family Moraceae. Figs are native to the area extending from southwestern Asia to the eastern Mediterranean [1]. There is evidence that figs were one of the first cultivated species in the Mediterranean region [2]. Fresh and dried fig fruits are popular with consumers because of their delicious taste and high nutritional and medicinal value [3]. According to Food and Agriculture Organization, the harvested area was 299,768 hectares in 2023, with production of approximately 1.304 million tons. Turkey and Egypt are the top fig producers, contributing 42% of the total world production, followed by Morocco, Algeria and Iran [4]. Scarcity of water resources, climate change phenomena and the increased population increase pressure on the available water resources for agriculture [5,6]. Wastewater is a promising alternative to fresh water, but it is considered to be ecologically dangerous, because it has high salt and toxic pollutants [7,8]. Soil salinization is a major problem in the agricultural sector of Egypt. In recent decades, 35% of irrigated area in Egypt has suffered from soil salinization. The severity of the salinity problem depends on features of the region’s climate, such as high temperature, winds, high irradiance, low relative humidity and the amount of rain [9]. Salinization is more pronounced in dry areas, where a greater amount of salt is brought in by irrigation with saline water than is removed by drainage [10]. Salinity is a multidimensional stress affecting crop growth and production [11]; high salt concentration in the root zone generates osmotic stress and accumulates Na+ and Cl ions to potentially toxic levels [12]. High salinity inhibits shoot, root and leaf growth and reduces photosynthesis pigments [13]. Moreover, plants subjected to salinity experience oxidative stress through an increase of reactive oxygen species [14]. Recently, attention has been paid to the application of agrochemical treatments to alleviate the detrimental effects of salt stress on crop growth; several compounds have been examined including a foliar application of proline [15], glycine betaine [16], salicylic acid [17], ABA [18] and mineral nutrients [19]. Sodium nitroprusside is a metal nitrosyl compound widely used to mediate different physiological processes of plants under abiotic stress conditions. The chemical breakdown of SNP produces nitric oxide (NO), a multifunctional signaling molecule involved in the regulation of physiological processes, e.g., expression of stress-related genes, stomata closure, and improved root development [20,21]. Also, NO prevents reactive oxygen species (ROS) injury by the regulation of antioxidant systems [22]. The role of SNP in alleviating the negative effect of salt stress has been investigated in a number of herbaceous plant species, but its effects on woody plants are not fully understood. Therefore, the main objective of this experiment is to clarify the effect of sodium nitroprusside (as an NO donor) to alleviate salinity stress injury in fig transplants cv. Conadria, through revealing the possible function of NO in regulating plant growth, maintaining proper nutrient balance and reducing oxidative damage. This will be helpful in understanding the protective effects of NO on woody plant species and how it could improve plant growth under salt stress conditions.

2. Results

2.1. Biomass and Plant Growth

According to the obtained data, salt stress significantly reduced the survival percentage of fig transplants compared to the negative control. SNP treatments significantly recorded higher values of survival percentage (Figure 1A); among the treatments, 200 µM SNP resulted in the highest survival percentage, followed by 100 and 50 µM.
The growth of salt-stressed fig transplants was enhanced by the exogenous SNP treatment. The transplant height as well as the number of leaves and leaf area from salt-stressed plants were significantly reduced compared to untreated negative control transplants. This reduction was significantly alleviated in response to all SNP treatments (Figure 1B–D); there are non-significant differences between shoot length and leaf number of salt-stressed fig transplants treated with SNP at 50 and 100 µM and fig transplants growing under normal conditions (negative control), while SNP at 100 µM recorded a higher value of leaf area compared with the positive control treatment (Figure 2).
Shoot and root fresh and dry weight markedly decreased under salt stress conditions compared to the untreated control treatment (Figure 3A). Regarding shoot fresh weight as well as shoot dry weight, the negative control recorded the highest values, while the lowest value was recorded for salt-stressed transplants. SNP at 50 and 100 µM recorded three-fold increases in shoot fresh weight compared with salt-stressed transplants, while a moderate increase was observed in the shoot dry weight of SNP-treated transplants. Similarly, exposure of fig transplants to salt stress significantly reduced root fresh and dry weight, even in SNP-treated transplants (Figure 3B). SNP at 50 and 100 µM improved root growth and recorded higher root fresh and dry weight compared with the positive control treatment.

2.2. Analysis of Mineral Elements

Data presented in Figure 4A–D showed a sharp increase in potassium, sodium and chloride concentration in fig leaves of transplants growing under salt stress conditions compared with un-stressed control plants, while a marked decrease was observed in the K/Na ratio. SNP at different concentrations reduced the accumulation of toxic sodium and chloride ions while increasing the accumulation of potassium and enhancing the K/Na ratio (Figure 4).

2.3. Chlorophyll Content

The photosynthetic pigments in the leaves of salt-stressed fig transplants were considerably impacted by SNP treatments (Chl a and b). A marked reduction of photosynthetic pigments was recorded in salt-stressed fig transplants (Figure 5). The lowest chlorophyll value was recorded for the positive control transplants; SNP treatments at 50 and 200 µM recorded Chl.a values approximately at the normal level in the negative control treatments, while Chl.b showed significantly higher values with all SNP concentrations compared with positive control treatments.

2.4. Proline Content

The data illustrated in Figure 6 showed that the proline content in salt-stressed fig transplants was significantly higher compared with the non-stressed fig transplants. The effect of SNP treatments on proline concentration was significant (p ≤ 0.05); SNP at 50 and 200 µM recorded proline concentrations similar to that of the non-stressed fig transplants, while SNP at 100 µM recorded significantly the lowest proline concentration compared with both the salt-stressed and the non-stressed transplants.

2.5. Total Phenol Content

The effects of SNP application on total phenolic concentration in fig transplants growing under salt stress conditions are illustrated in Figure 7. Statistical analysis (p ≤ 0.05) showed a marked increase in phenolic content in the leaves of salt-stressed transplants. SNP showed a dose-dependent decrease in phenolic content; 100 µM SNP foliar application recorded the highest reduction in the phenolic content of salt-stressed transplants.

2.6. Lipid Peroxidation

The data illustrated in Figure 8 showed the effect of SNP treatment on malondialdehyde levels in fig leaves growing under salt stress compared to control treatments; the obtained results indicated that salt stress significantly increased MDA concentration, even in the SNP-treated transplants. The leaves of salt-stressed fig transplants accumulated a 2.5-fold increase in MDA (11.44 µmol/g-FW) compared with the non-stressed control transplants (4.45 µmol/g-FW). MDA concentration was significantly reduced with SNP treatments; the lowest MDA concentration of salt-stressed transplants was recorded for SNP at 100 µM (5.97 µmol/g-FW), followed by SNP at 50 and 200 µM (6.62 and 8.28 µmol/g-FW, respectively).

2.7. Antioxidant Enzymes Activity

The activities of CAT, POD and SOD were determined to assess the role of SNP in the regulation of antioxidant enzyme activity under salt stress. Antioxidant enzyme activity showed a sharp increase in salt-stressed transplants (Figure 9A–C). The CAT and SOD activity of salt-stressed transplants showed a more than two-fold increase compared with untreated control transplants. POD activity followed a similar pattern and increased by 36%. CAT activity in SNP-treated transplants was significantly (p ≤ 0.05) lower than that of the salt-stressed transplants; the lowest value was recorded for SNP at 50 µM.
POD activity was significantly (p ≤ 0.05) influenced by salt stress and SNP treatments; POD increased in salt-stressed transplants (5.87 U mg−1) compared to the negative control (3.75 U mg−1) but significantly (p ≤ 0.05) decreased with SNP treatments (4.48, 4.20 and 5.01 U mg−1 for 50, 100 and 200 µM of SNP, respectively). Similarly, under salt stress conditions, SOD activity in the leaves of fig transplants showed a sharp increase, reaching the highest value (15.73 U mg−1) compared to the transplants growing under normal conditions (negative control). SNP treatment at 50 and 100 µM significantly decreased SOD activity to close to its normal level (Figure 9C).

2.8. The Hierarchical Clustering Heatmap

The trend of the change in the measured parameters under salt stress and SNP treatments was displayed in the hierarchical clustering heatmap. The measured parameters were grouped into three column clusters (Figure 10).
Cluster-A includes shoot fresh and dry weight as well as root fresh and dry weight; parameters of cluster-A decreased in salt-stressed transplants, but SNP-treated transplants recorded higher values compared with salt-stressed transplants. Mineral content (K, Na, Cl), K/Na ratio, leaf number, leaf area, (Chl.a and Chl.b), total phenols and POD levels were grouped in cluster-B. Compared with the salt-stressed transplants (positive control), most cluster-B parameters showed an increasing pattern in the SNP-treated transplants, while POD, Na and Cl showed a decreasing pattern. Cluster-C comprises survival percentage, plant height, proline, MDA, CAT and SOD, which was decreased in salt-stressed transplants compared with the negative control. Cluster-C parameters showed a marked increase in SNP-treated transplants compared with salt-stressed plants. Moreover, the heat map represents the behavior of fig transplants under both normal (negative control) and salt stress (positive control) conditions, as well as the effect of SNP concentrations. The studied treatments were grouped into two main column-clusters. The first one represents salt-stressed transplants; the second cluster was further divided into sub-clusters consisted of treatments with closely related behavior. SNP at 50 and 100 µM were close to the normal, un-stressed transplants.

3. Discussion

The obtained results showed that salt stress affected the whole transplant growth, which may be due to the osmotic stress and accumulation of toxic ions, which lead to the reduction of cell division and expansion, suppression of leaf expansion [23], inhibition of photosynthesis, nutrient imbalance and over-production of ROS, which negatively affect plant growth [24]. The obtained results showed that salinity stress negatively affected shoot length, shoot and root fresh and dry weights, leaf number and leaf area; similar results were reported previously [24,25]. SNP application promoted shoot growth and enhanced fresh and dry weight, leaf number and leaf area compared with non-treated plants. The enhancement in growth parameters may be due to improved physiological and metabolic processes [20]. Nitric oxide enhances membrane fluidness and improves cell enlargement [26]. Moreover, SNP enhanced nutrient absorption, regulated plant hormones and improved photosynthetic efficiency; hence, it increased biomass accumulation [27,28]. SNP reduced the sodium content, increased the potassium content and enhanced the K/Na ratio. Salt accumulation in the root zone inhibited the absorption of mineral nutrients, i.e., K+, Ca2+ and NO3+, and accumulated Na+ and Cl to a toxic levels [12,29]. The results of our investigation showed that SNP improved the absorption of K+ and reduced Na+ and Cl- content in fig leaves; similar results were reported in barley [30], sunflower [31], Brassica oleracea [32] and Salicornia persica [33]. The change in ionic balance (relatively lower Na+ and higher K+ leaf content) could be due to the effect of NO on plasma membrane V-H+-ATPase and PM-H+-ATPase pumps, which control Na+ and K+ transportation [34,35]. Increasing K absorption and enhancing the K/Na ratio enable plants to survive under salinity stress conditions. K+ plays a vital role in regulating various metabolic reactions; a higher K/Na ratio decreases lipid peroxidation and improves photosynthesis and metabolite translocation, as well as activating antioxidant enzymes and thus increasing plant growth [12,29,32]. The observed reduction in photosynthetic pigments in fig leaves may be due to the activity of proteolytic enzymes such as chlorophyllase [36]. There are numerous reports of decreased levels of chlorophylls under salt stress [13,25,37]. According to Aras et al. [38], SNP promotes the biosynthesis of chlorophyll pigments and/or activates the chlorophyll repair mechanism [39,40].
Our results showed an increase in the proline content of salt-stressed fig transplants; proline plays key role in avoiding cellular dehydration through the maintenance of turgor pressure of stressed plants [41]. Moreover, proline is a non-enzymatic scavenger of free ROS; hence, it protects the cellular membrane, nucleic acids, enzymes and proteins [42]. Consistent with our results, an increase in proline content was reported in various plant species under salt stress [41]. Our findings showed a significant reduction in proline of SNP-treated transplants; the decreased proline content was previously reported in Lolium [43] and Salicornia persica [33] treated with SNP under salt stress conditions. The observed reduction in proline contents of SNP-treated fig transplants can be attributed to the effect of NO on the expression of Δ1-pyrroline -5-carboxylate synthetase [44]. Also, SNP can activate proline dehydrogenase, which induces the degradation of proline content [45]. Phenolics are non-enzymatic compounds evolved under stress conditions that have important a protective role against oxidative stress [46,47]. Several plant species accumulate high levels of phenolic compounds under stress conditions as a defense mechanism [48]. Phenolic compounds play an important role in scavenging free radicals, inhibiting lipid peroxidation and maintaining membrane integrity [46,47,49]. An elevated level of phenolics may exhibit the level of stress injury; thus, it can be interpreted that low phenolic contents show low stress injury [38]. A decreased amount of phenolics was observed in chilling-stressed banana plantlets treated with ABA acid [50] and SNP-treated apple transplants growing under salt stress conditions [38].
Reactive oxygen species are by-products of cellular metabolic activity. ROS are regularly removed through antioxidant activity systems; the accumulation of ROS under stress conditions causes injury to cellular membranes, organelles and nucleic acids and reduces enzyme activity and photosynthesis pigments. NaCl stress induces the overproduction of reactive oxygen species that cause membrane lipid peroxidation and increase MDA content [51]. Lipid peroxidation is an important sign of oxidative damage [51,52]. According to the obtained results, SNP reduced the extent of membrane damage (expressed as lower malondialdehyde content). The results indicate that SNP improved salt tolerance via alleviating oxidative damage and maintaining plasma membranes’ permeability under salinity conditions [30,38,53]. Moreover, NO may reduce cell membrane injury by eliminating the accumulation of ROS. Decreasing levels of lipid peroxidation of NaCl-stressed plants in response to SNP treatments have been reported in different plant species [39,54,55], as the plants have both enzymatic and non-enzymatic defense systems for scavenging ROS [56,57,58]. The ROS scavenging systems include antioxidant enzymes, i.e., superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), to protect plants against oxidative stress injury [56,58,59]. In the present investigation, the activities of antioxidant enzymes showed a decreasing trend after foliar application of SNP. Nitric oxide plays a protective role by reacting with free radicals. NO can directly scavenge ROS [60,61] or indirectly scavenge them by enhancing antioxidant enzyme activity [28]. NO directly reacts with superoxide radicals and consequently reduces SOD activity; similar findings were reported [62,63].

4. Materials and Methods

4.1. Plant Materials and Salinity Stress Treatments

The current experiments were conducted in a greenhouse situated at 31°12′65″ E longitude, 30°00′48″ N latitude. The greenhouse was covered with 73% shade-net; the average temperature ranged from 28 to 35 °C, with a photoperiod ranging from 12 to 14 h during the experiment period. Homogenous one-year-old transplants were pruned to only one shoot and transplanted in 15 L plastic bags filled with sandy soil (86% sand) at the end of the dormancy season (late February). The sand was washed several times to remove the soluble salts before the beginning of salt treatments (EC = 0.5 ds/m). Plants were irrigated twice per week with 1500 mL of half-strength Hoagland nutrient solution for 30 days before treatment began through drip irrigation system with one built in emitter (4.0 L h−1). The plants were subjected to two salinity stress levels, i.e., non-saline control and severe salt stress by irrigating the pot with 1500 mL of half-strength Hoagland nutrient solution containing 6.25/m of NaCl. Irrigation of negative control transplants was carried out using tap water (EC = 0.48 dS/m); salinity treatments were applied incrementally to avoid osmotic shock to fig transplants. SNP was applied as a foliar application at 0.0, 50, 100 and 200 µM. The effects on salt stress on fig transplants were assessed through the following measurements:

4.2. Biomass and Plant Growth

After five month of salinity and SNP treatments, fig plants were harvested, and the following parameters were measured: survival percentage, plant height (cm), leaf area (cm2), number of green leaves, fresh and dry weights of shoot and root system (g).

4.3. Analysis of Mineral Elements

Leaf samples were left to air-dry for 72 h at room temperature and grounded to fine powder; 0.2 g sample digested using sulfuric acid and hydrogen peroxide until clear solution was obtained. Total nitrogen was determined by the modified Micro-Kjeldahl method [64], phosphorus was measured colorimetrically [65], Na+ and K+ were determined by Flame apparatus [66], and leaf chloride content (Cl) was determined by titration method [67].

4.4. Chlorophyll Content

Leaf sections (0.5 g) were ground in 80% acetone (v/v) for chlorophyll determination, absorbance was measured at 663 and 646 nm, and the chlorophyll content was determined [68].

4.5. Proline

Proline content was quantified using ninhydrin method [69]. Proline was extracted from 0.5 g fresh leaf sample in 3% aqueous sulfosalicylic solution (w/v), and 2 mL of the extraction was mixed with 2 mL of acid ninhydrin and 2 mL of glacial acetic acid and boiled in water bath for 1 h; the reaction was terminated by cooling in an ice bath. The red color of the reaction was extracted in 4 mL of toluene; color intensity was determined at 520 nm. Proline concentration was estimated from standard curve and calculated according to Bates et al. [69].

4.6. Total Phenol Content

The total phenols were determined colorimetrically according to Folin–Ciocalteu procedure [70]. A total of 0.5 g of leaf sample was ground in 20 mL of a methanol (v/v) solution. One mL of Folin–Ciocalteu reagent was added to 1 mL of leaf extract and left to react at room temperature (6 min). Then, 4 mL of 1 M Na2CO3 was added, and reaction volume was adjusted to 10 mL using distillated water and incubated in darkness for 90 min; the absorbance was measured at 760 nm using a spectrophotometer. Total phenolic concentration was estimated from standard curve and expressed as mg of equivalent gallic acid per g FW.

4.7. Lipid Peroxidation

The thiobarbituric acid (TBA) method was used to measure the amount of lipid peroxidation [71]. A total of 0.5 g of leaf sample was ground in 3 mL of 10% w/v trichloroacetic acid (TCA); the mixture was centrifuged at 15,000× g for 20 min. One milliliter of 20% TCA and 0.5% (w/v) TBA was combined with 0.2 mm of the supernatant. After 30 min of heating the mixture at 95 °C, it was rapidly cooled in an ice bath to stop the reaction; the absorbance of the supernatant was measured at 534 nm.

4.8. Extraction and Determination of Antioxidant Enzymes Activity

In order to prepare the crude enzyme, 0.5 g of fresh leaf sample was ground in liquid nitrogen, homogenized in phosphate buffer pH 6.8 (0.1 M) and centrifuged for 20 min at 20,000 rpm under cooling [72].

4.8.1. Catalase (CAT) Activity

Catalase (E.C.1.11.1.6) activity was estimated by measuring the breakdown of H2O2 in reaction mixture. The reaction was initiated by adding 50 µL of enzyme extract to 9.96 mL of H2O2 in phosphate buffer pH 7.0. The decrease in absorbance was measured at 60 s intervals at 250 nm using a UV–VIS spectrophotometer [73].

4.8.2. Peroxidase (POX) Activity

Peroxidase (EC 1.11.1.7) activity was quantified according to Du et al. [74]. The reaction mixture consisted of 2.8 mL substrate solution prepared by dissolving 0.02 mol/L catechol in 0.05 mol/L sodium phosphate buffers (pH7.0) and 0.2 mL of the enzyme extract. The change in optical density was determined spectrophotometrically within 60 s at 470 nm. A unit of enzyme activity was defined as the change in absorbance value per minute.

4.8.3. Superoxide Dismutase (SOD) Activity

SOD (EC 1.15.1.1) activity was determined by measuring the autoxidation of pyrogallol [75]. The reaction mixture was prepared by adding of 0.1 mL of enzyme extract to 3.6 mL of distilled water, 0.8 mL of 3 mM pyrogallol and 5.5 mL of 50 mM phosphate buffer (pH 7.8). The rate of oxidation of pyrogallol was measured at 325 nm; one unit of enzyme is the amount of the enzyme leading to 50% inhibition of the auto-oxidation of pyrogallol in 1 min at 25 °C.

4.9. Experimental Design and Statistical Analysis

The treatments were arranged in a completely randomized block design with three replicates (8 pots for each replicate). Data were subjected to one-way ANOVA analysis [76] using MSTAT-C, version 2.10 statistical package software. Means were compared according to Duncan’s multiple range tests at significance level of 5% [77]. A hierarchical cluster analysis between the examined SNP treatments and the measured variables was performed using the ClustVis online tool [78].

5. Conclusions

The obtained results clarify the role of SNP (nitric oxide donor) in reducing the negative effect of salt stress on fig transplants. The appropriate dosage of SNP (100 µM) efficiently maintains nutrient balance, improves chlorophyll content, decreases the concentration of MDA and regulates antioxidant enzyme activities. SNP application can be recommended as a promising practice for alleviating salt stress on fig trees. Further studies are needed to understand the long-term effect of NO on field-growing trees and the possible effect on fruiting behavior.

Author Contributions

Conceptualization, E.S.H.; methodology, A.A. and R.B.; validation, A.A. and R.B.; investigation, E.S.H., A.A. and R.B.; resources, A.A.; data curation, R.B.; writing—original draft preparation, A.A.; writing—review and editing, A.A. and R.B.; visualization, E.S.H.; supervision, E.S.H.; funding acquisition, R.B. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

Data are available upon request.

Acknowledgments

The authors would like to express special gratitude to the Faculty of Agriculture, Cairo University for all facilities during this work.

Conflicts of Interest

The authors declare no conflict of interest.

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Figure 1. Impact of salt stress and SNP concentrations on growth parameters of fig transplants; survival percentage (A), plant height (B), number of leaves (C) and leaf area (D). The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
Figure 1. Impact of salt stress and SNP concentrations on growth parameters of fig transplants; survival percentage (A), plant height (B), number of leaves (C) and leaf area (D). The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
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Figure 2. Impact of salt stress and SNP concentrations on leaf area of fig transplants: negative control (A), positive control (B), SNP at 50 µM (C), SNP at 100 µM (D), SNP at 50 µM (E).
Figure 2. Impact of salt stress and SNP concentrations on leaf area of fig transplants: negative control (A), positive control (B), SNP at 50 µM (C), SNP at 100 µM (D), SNP at 50 µM (E).
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Figure 3. Impact of salt stress and SNP concentrations on shoot and root weight of fig transplants; shoot fresh and dry weight (A) and root fresh and dry weight (B). The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
Figure 3. Impact of salt stress and SNP concentrations on shoot and root weight of fig transplants; shoot fresh and dry weight (A) and root fresh and dry weight (B). The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
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Figure 4. Impact of salt stress and SNP concentrations on potassium (A), sodium (B), chloride (C) and K/S ratio (D) of fig leaves. The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
Figure 4. Impact of salt stress and SNP concentrations on potassium (A), sodium (B), chloride (C) and K/S ratio (D) of fig leaves. The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
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Figure 5. Impact of salt stress and SNP concentrations on photosynthetic pigment (Chl.a, Chl.b) content of fig leaves. The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
Figure 5. Impact of salt stress and SNP concentrations on photosynthetic pigment (Chl.a, Chl.b) content of fig leaves. The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
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Figure 6. Impact of salt stress and SNP concentrations on proline content of fig leaves. The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
Figure 6. Impact of salt stress and SNP concentrations on proline content of fig leaves. The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
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Figure 7. Impact of salt stress and SNP concentrations on total phenolic content of fig leaves. The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
Figure 7. Impact of salt stress and SNP concentrations on total phenolic content of fig leaves. The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
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Figure 8. Impact of salt stress and SNP concentrations on malondialdehyde content of fig leaves. The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
Figure 8. Impact of salt stress and SNP concentrations on malondialdehyde content of fig leaves. The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
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Figure 9. Impact of salt stress and SNP concentrations on activity of SOD (A), CAT (B) and POD (C) of fig leaves. The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
Figure 9. Impact of salt stress and SNP concentrations on activity of SOD (A), CAT (B) and POD (C) of fig leaves. The results are expressed as means ± SD. There is no significant difference between means with the same alphabetic letters.
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Figure 10. Hierarchical clustering with heatmap illustrating the SNP-variable relationships under salt stress. Each row represents a treatment, whereas each column represents a trait; red color represents higher values of the measured parameters, and blue color represents the values.
Figure 10. Hierarchical clustering with heatmap illustrating the SNP-variable relationships under salt stress. Each row represents a treatment, whereas each column represents a trait; red color represents higher values of the measured parameters, and blue color represents the values.
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Hegazi, E.S.; Abdallatif, A.; Burshaid, R. Enhancing Salinity Tolerance of Fig Transplants Cv. Conadria via Exogenous Application of Sodium Nitroprusside. Stresses 2025, 5, 36. https://doi.org/10.3390/stresses5020036

AMA Style

Hegazi ES, Abdallatif A, Burshaid R. Enhancing Salinity Tolerance of Fig Transplants Cv. Conadria via Exogenous Application of Sodium Nitroprusside. Stresses. 2025; 5(2):36. https://doi.org/10.3390/stresses5020036

Chicago/Turabian Style

Hegazi, El Said, Abdou Abdallatif, and Rashid Burshaid. 2025. "Enhancing Salinity Tolerance of Fig Transplants Cv. Conadria via Exogenous Application of Sodium Nitroprusside" Stresses 5, no. 2: 36. https://doi.org/10.3390/stresses5020036

APA Style

Hegazi, E. S., Abdallatif, A., & Burshaid, R. (2025). Enhancing Salinity Tolerance of Fig Transplants Cv. Conadria via Exogenous Application of Sodium Nitroprusside. Stresses, 5(2), 36. https://doi.org/10.3390/stresses5020036

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