Maximizing Leaves, Inflorescences, and Chemical Composition Production of Moringa oleifera Trees under Calcareous Soil Conditions

One of the main issues limiting plant productivity is a lack of soil nutrient resources, especially in calcareous soil, which covers more than one third of the world’s land surface area. On the other hand, despite rising demand for all parts of the Moringa oleifera tree, several studies have focused on its leaf production as an herbaceous plant, rather than as a tree, and no extensive research has been carried out on leaf and inflorescence production in the mature tree. As a result, the influence of vermicompost and NPK (minerals and nanoparticles), as well as their combination, under calcareous soil conditions, was investigated in this study. The experiment was set up as a split plot in Randomized Complete Block Design (RCBD) with three replicates. In both seasons considered in this study, it was discovered that increasing the quantity of vermicompost and employing NPK fertilization, as well as their combination treatments, greatly enhanced all parameters and yield of distinct Moringa oleifera tree parts. Furthermore, the combination treatment T21 yielded the highest mean values of growth, leaves, and chemical composition parameters, as well as the highest yield from the Moringa oleifera tree. In both seasons, the highest number of inflorescences per tree, as well as the yield of fresh and dry inflorescences, was measured using combination treatment T18. In both seasons, however, increasing the level of vermicompost, NPK, and their combination treatments significantly reduced the total phenolic and flavonoid content and antioxidant activity of dry Moringa oleifera leaves.


Introduction
The main factor in agriculture is soil, which provides the nutrient content and affects the strength of plants. Agricultural production in calcareous soils faces numerous challenges due to high infiltration rates, low level of organic matter, water holding capacity, cation-exchange capacity, clay content, poor structure, loss of nutrients due to leaching or deep percolation, high pH with low availability of nutrients, and a nutritional imbalance between elements. These challenges can make it difficult to achieve the desired plant development and output [1][2][3][4]. Potassium (K) plays an important part in a variety of biochemical and physiological processes that affect plant growth, productivity, and disease resistance. It has the ability to improve photosynthesis, control osmotic conditions, and stimulate carbohydrate metabolism. Plants, therefore, require a lot of K for economic crop

Growth Characteristics
The growth characteristics of the Moringa oleifera tree were significantly affected by the application of organic and NPK fertilization as well as their combination treatments in both seasons. Figure 1 indicates that the addition of 60 ton ha −1 of vermicompost led to the best growth characteristics of Moringa oleifera trees including significant maximum mean values of plant height (217.8 cm and 216.0 cm), stem diameter (59.60 mm and 58.75 mm), number of main branches per tree (6.84 and 6.99), and number of leaves per branch (9.29 and 9.41), compared to the other vermicompost treatments and control, in the first and second seasons, respectively. Regarding NPK application, using 2 g L −1 of Nano-NPK gave the highest significant response to plant height (204.8 cm and 203.1 cm), stem diameter (56.02 mm and 55.22 mm), number of main branches per tree (6.08 and 6.21), and number of leaves per branch (8.90 and 9.02) during both studied seasons, respectively ( Figure 1). In addition, for combination treatments, it was observed that the significant tallest plants (240. 8

Weight and Yield of Fresh and Dry Leaves
The fresh and dry weights of leaves as well as their yield per tree and per hectare were significantly affected by the application of organic fertilization and mineral fertilization, as well as their combination treatments, in both seasons of this study in comparison to the control; see Figures 2 and 3; Tables 3 and 4. The significant highest mean values of fresh leaf weight (7.75 g and 7.40 g), yield of fresh leaves per tree (505 g tree and 498 g tree −1 ), yield of fresh leaves per hectare (5049 kg ha −1 and 4976 kg ha −1 ), dry leaf weight (2.32 g and 2.22 g), yield of dry leaves per tree (151.5 g tree −1 and 149.3 g tree −1 ), and yield of dry leaves per hectare (1515 kg ha −1 and 1493 kg ha −1 ) in the first and second seasons, respectively, were noticed with the addition of 60 ton ha −1 of vermicompost. Moreover, for the mineral fertilization applications, the application of 2 g L −1 Nano-NPK had the maximum significant mean values of fresh leaf weight (7.15 g and 6.83 g), yield of fresh leaves per tree (422 g tree −1 and 416 g tree −1 ), yield of fresh leaves per hectare (4221 kg ha −1 and 4159 kg ha −1 ), dry leaf weight (2.15 g and 2.05 g), yield of dry leaves per tree (126.6 g tree −1 and 124.8 g tree −1 ), and yield of dry leaves per hectare (1266 kg ha −1 and 1248 kg ha −1 ) in both seasons, respectively. When comparing combination treatments, the maximum mean values of fresh leaf weight (8.33 g and 7.95 g), yield of fresh leaves per tree (674 g tree −1 and 664 g tree −1 ), yield of fresh leaves per hectare (6739 kg ha −1 and 6641 kg ha −1 ), dry leaf weight (2.50 g and 2.39 g), yield of dry leaves per tree (202.2 g tree −1 and 199.2 g tree −1 ), and yield of dry leaves per hectare (2022 kg ha −1 and 1992 kg ha −1 ) in both seasons, respectively (Tables 3-5) were observed with the application of treatment T21.
199.2 g tree −1 ), and yield of dry leaves per hectare (2022 kg ha −1 and 1992 kg ha −1 ) in both seasons, respectively (Tables 3-5) were observed with the application of treatment T21.

Figure 2.
In both seasons of the study, the mean values of fresh weight of leaves (g), yield of fresh leaves (g tree −1 ), yield of fresh leaves (kg ha −1 ), and dry weight of leaf (g) of Moringa oleifera trees as influenced by vermicompost and NPK fertilization are provided below. The data are presented as a mean with standard error (n = 3). Bars with identical lowercase letters are not significant at the 0.05 level of probability.

Inflorescences Parameters
All NPK and vermicompost levels, as well as their combinations treatments, significantly affected inflorescence parameters of the Moringa oleifera, as well as their yield, at the 0.05% probability level. According to the results in Figures 3 and 4; Tables 4 and 5, it was observed that the maximum mean values of the fresh weight of inflorescences (6.12 g and 6.20 g) and the dry weight of inflorescences (1.77 g and 1.80 g) were recorded with the dose of 60 ton ha −1 vermicompost in the first and second seasons, respectively. Meanwhile, the highest mean values of inflorescence numbers per tree (51.6 and 53.2) were noticed with the dose of 50 ton ha −1 vermicompost in two seasons, respectively. With NPK fertilizer, 2 g L −1 of Nano-NPK significantly gave the highest response to the number of inflorescences per tree (44.7 and 45.3) and the fresh weight of inflorescences (5.51 and 5.58) between the NPK and vermicompost combination treatments. Moreover, the maximum mean values of the fresh weight of inflorescences (6.95 g and 7.04 g) and the dry weight of inflorescences (2.13 g and 2.16 g) were found with combination treatment T21 in both seasons, respectively. On the other hand, the highest mean values of inflorescences number per tree (70.6 and 73.5) in the two studied seasons, respectively, were found with the plants provided treatment T18 in both seasons, respectively.    Tables 5 and 6, illustrate that all NPK and vermicompost levels, as well as their combination treatments, significantly affected the fresh and dry inflorescence yields of Moringa oleifera at the 0.05% probability level. According to the results in Tables 7-9, with a 50 ton ha −1 vermicompost dose, the maximum mean values of fresh inflorescence yield per tree (307.8 g tree −1 and 320.6 g tree −1 ) and per hectare (3078 kg ha −1 and 3206 kg ha −1 ), and yield of dry inflorescences per tree (87.7 g tree −1 and 91.6 g tree −1 ) and per hectare (877 kg ha −1 and 927 kg ha −1 ) were observed in the two seasons, respectively. In terms of NPK fertilizer treatment, using 2 g L −1 of Nano-NPK resulted in the maximum response output of fresh inflorescences per tree (262.7 g tree −1 and 276.0 g tree −1 ) and per hectare (2627 kg ha −1 and 2760 kg ha −1 ), and yield of dry inflorescences per tree (75.2 g tree −1 and 78.6 g tree −1 ) and per hectare (752 kg ha −1 and 786 kg ha −1 ) in the two seasons, respectively. The interaction between the NPK and vermicompost treatments was substantial in the combination treatments. Furthermore, the plants provided treatment T18 had the highest mean values of fresh inflorescences per tree (461.8 g tree −1 and 485.9 g tree −1 ) and per hectare (4618 kg ha −1 and 4859 kg ha −1 ) in the first and second seasons, respectively, as well as yield of dry inflorescences per tree (135.8 g tree −1 and 143.2 g tree −1 ) and per hectare (1358 and 1432). Table 6. The influence of combined treatments of vermicompost and NPK fertilization on the mean values of yield of dry inflorescences (g tree −1 ), yield of dry inflorescences (kg ha −1 ), and total chlorophyll (spad unit) of Moringa oleifera trees in the first and second seasons.

Total Chlorophyll, Leaf Soluble Protein, and Vitamin C Contents
It is clear from Figure 5 and Tables 6 and 7 that the studied treatments of vermicompost, NPK, and their combination treatments in both seasons led to significant differences for total chlorophyll, leaf soluble protein, and vitamin C of the Moringa oleifera leaves in both seasons. They increased with increasing vermicompost level. Moreover, this increase reached its maximum level with the application of 60 ton ha −1 vermicompost for total chlorophyll (39.1 spad unit and 39.2 spad unit), leaf soluble protein (27.2 mg g −1 and 27.6 mg g −1 ), and vitamin C (48.7 mg g −1 and 50.9 mg g −1 ) in the two seasons, respectively, compared with the other levels of vermicompost. Meanwhile, the application of 2 g L −1 Nano-NPK led to the maximum mean values of total chlorophyll (37.7 spad unit and 37.8 spad unit), leaf soluble protein (26.0 mg g −1 and 26.4 mg g −1 ) and vitamin C (45.4 mg g −1 and 47.5 mg g −1 ), compared with the other NPK treatments in the two seasons, respectively. In a comparison of combination treatments, the maximum mean values of total chlorophyll (40.3 spad unit and 40.4 spad unit), leaf soluble protein (28.9 mg g −1 and 29.3 mg g −1 ), and vitamin C content (53.7 mg g −1 and 56.1 mg g −1 ) were noticed with the treatment T21 in the first and second seasons, respectively.

Total Phenoliccontent, Flavonoid Content and Antioxidant Activity
From Figure 6 and Table 8 it is obvious that in contrast to the other studied parameters in this experiment, the total phenolic content, flavonoid content, and antioxidant activity of Moringa oleifera dry leaves decreased significantly after the application of vermicompost, NPK, and their combination treatments in both seasons. This means that the maximum mean values of total phenolic content (43.16 mg Gallic g −1 dry herb and 44.17 mg Gallic g −1 dry herb), flavonoid content (25.13 mg Rutin g −1 dry herb and 25.72 mg Rutin g −1 dry herb), and antioxidant activity (33.98 µg ml −1 for 50% inhibition and 34.77 µg ml −1 for 50% inhibition) were found with 0 ton ha −1 vermicompost (control) in the two seasons, respectively, compared with all levels of vermicompost. Furthermore, the application of 0 g L −1 NPK (control) gave the maximum mean values of total phenolic content (40.02 g Gallic g −1 dry herb and 40.96 g Gallic g −1 dry herb), flavonoid content (22.80 mg Rutin g −1 dry herb and 23.34 mg Rutin g −1 dry herb), and antioxidant activity (37.95 µg mL −1 for 50% inhibition and 38.84 µg mL −1 for 50% inhibition) compared with both treatments of NPK in the two seasons, respectively. For combination treatments, the maximum mean values of total phenolic content (47.12 g Gallic g −1 dry herb and 48.23 g Gallic g −1 dry herb), flavonoid content (28.01 mg Rutin g −1 dry herb and 28.67 mg Rutin g −1 dry herb), and antioxidant activity (30.70 µg mL −1 for 50% inhibition and 31.42 µg mL −1 for 50% inhibition) were recorded with treatment T1 (control treatment) in the two seasons, respectively.

Phosphorus and Potassium Contents
The phosphorus and potassium content results of Moringa oleifera leaves provided in Figure 7 and Table 9 show that the phosphorus and potassium contents increased significantly with the application of vermicompost, NPK, and their combination treatments in both seasons. In comparison to the other levels of vermicompost, the maximum mean values of phosphorus content (0.272% P 2 O 5 and 0.298% P 2 O 5 ) and potassium content (3.41% K 2 O and 3.74% K 2 O) were observed with the application of 60 ton ha −1 vermicompost in the two seasons, respectively. In addition, when compared to the other NPK treatments, the administration of 2 g L −1 Nano-NPK resulted in the highest mean values of phosphorus content (0.263% P 2 O 5 and 0.288% P 2 O 5 ) and potassium content (3.16% K 2 O and 3.46% K 2 O) in both seasons. In the first and second seasons, the treatment T21 resulted in the highest mean values of phosphorus (0.282% P 2 O 5 and 0.309% P 2 O 5 ) and potassium contents (3.63% K 2 O and 3.98% K 2 O), respectively.

The Impact of Calcareous Soil on Moringa oleifera Growth Characteristics, Yield, and Chemical Constituents
The seeds of Moringa oleifera were able to emerge in calcareous soil without any organic or inorganic fertilization treatments in this experiment (control treatment). The seedlings, on the other hand, grew slowly after that. Finally, they created a miniature tree that resembled a narrow branch with a modest number of leaves and inflorescences. These showed the minimal mean values of growth parameters, yield of fresh and dried leaves and inflorescences, as well as the content of chemical substances including vitamin C, potassium, and phosphorus in the Moringa oleifera leaves. In contrast, in the extract from the Moringa oleifera dry leaves of the control trees, the highest mean values of total phenolic content, flavonoid content, and antioxidant activity were observed. In calcareous soil, this could be due to a lack of soil nutrients and their accessibility. Leaching, deep percolation, and nitrogen transformations all contribute to nitrogen loss, low availability of phosphorous and micronutrients, as well as imbalances among potassium, magnesium, calcium, and other elements [1][2][3]50].
These findings are in line with those of Haukioja et al. [51], who discovered that when N is scarce, the metabolism of developed plants shifts toward the synthesis of non-Ncontaining secondary metabolites, such as phenolic and terpenoids. According to Bavaresco and Poni [52], calcareous soil lowers P and K levels in various organs of the plant, reducing overall canopy photosynthesis. As a result, the plant's dry matter suffers, resulting in lower inflorescence production as Khan and Qasim [53] found in wheat plants grown in calcareous soil. When compared to supplements with compost and spent grain, squash germination parameters recorded the lowest values after 15 days of seeding in calcareous soil, according to Aboukila et al. [4]. Semida et al. [54] found that untreated plants growing in salty calcareous soil had the lowest growth metrics, total soluble sugar concentrations, free proline, anthocyanin concentrations, and photosynthetic efficiency.

Effects of Vermicompost on Moringa oleifera Tree Yield, Growth Parameters, and Its Chemical Components
The collected results demonstrate that increasing the amount of vermicompost used boosts the improvement in all analyzed parameters throughout the course of the two seasons considered in the study. This improvement could be attributed to the role of endogenous auxins, gibberellins, and cytokinins in regulating growth in vermicompost. Furthermore, mineralizing organic matter, increasing soluble forms of nutrients by modifying soil pH, and promoting element uptake by roots are all ways to increase the availability of plant nutrients in the soil, such as nitrogen, phosphorus, potassium, and microelements [22,55,56]. Furthermore, utilizing vermicompost improves the physical and chemical qualities of calcareous soil. Due to its slow rate of nutrient breakdown, vermicompost fertilizer is suited for Moringa oleifera trees, due to their extended growing season [35,57]. Other researchers have found that increased vermicompost consumption improved vegetative features and increased leaf and flower number, length, fresh and dry weight, total chlorophyll, greenness, yield, and plant secondary products in plants [38,39,58].
Furthermore, Arancon et al. [35] (in petunias), Atiyeh et al. [59] (in marigolds), Arancon et al. [60] (in strawberries), Liuc and Pank [61] (in Roman Chamomile), and Muscolo et al. [62] (in carrots) all discovered that the application of vermicompost increased growth, blooming parameters, and all quantitative and qualitative parameters. Furthermore, vermicompost has been found to improve the nutritional quality of the plants as well as development, flowering, yield, and chemical composition of pakchoi [56], strawberries [63], lettuce [64], and Chinese cabbage [65]. These findings are consistent with those of [62][63][64][65][66][67][68][69], who observed a considerable increase in yield and accumulation of N, P, K, Ca, and Mg in the root and shoot system after treating plants with vermicompost or its water-extractable fraction. This could be linked to the role of vermicompost in enhancing plant nutrient availability in the soil by adding micro and macronutrients during the decomposition of organic matter, modifying soil pH to increase soluble forms of nutrients, and increasing element uptake by the roots [22,55,56]. In addition, while increasing vermicompost enhanced vitamin C content and total carotenoids, it decreased antioxidant activity as well as total phenolics and flavonoids. This could be due to the metabolism of grown plants moving toward the production of N-compounds and away from non-N-containing secondary metabolites, such phenolics and terpenoids under high-N circumstances [70,71]. Lowering N concentrations, mineral nutrient levels, and enhanced phenolic compound accumulation in plant tissue all boost the antioxidant capability of leaves [56,[72][73][74]. Moreover, despite the discovery by Law-Ogbomo et al. [75] that applying poultry manure to okra plants increased growth, yield, and P, K, Na, and Mn content, vermicompost is preferable over manure and plant compost in most situations, according to Ngo et al. [76] and Aryal and Tamrakar [77]. The application of vermicompost resulted in increased height, diameter, and yield, when compared to farmyard manure.

Effects of NPK Fertilizer on Moringa oleifera Growth Parameters, Yield, and Chemical Components
N, P, and K are the three most important nutrients for crops, and a deficiency of any of these elements during crop growth is well known to have a negative impact on the plant's reproductive ability, growth, and yield [78][79][80]. These elements are in charge of a multitude of enzymatic and metabolic processes, as well as seed, pod, inflorescence, shoot, and root health. In both considered seasons, and under alkaline calcareous soil conditions, foliar application of Nano-NPK surpassed the ground application of NPK in reaching the best mean values of the examined growth traits, yield, and chemical components of Moringa oleifera trees, according to the findings of this study. Foliar fertilization has a better chance of resolving nutritional deficits in plants caused by poor nutrient transport to the roots and, in alkaline calcareous soils, it is usually more cost-effective and efficient [81][82][83]. Normal fertilizers, on the other hand, are typically lost to the environment and are incapable of being absorbed by plants, resulting in considerable economic and resource losses as well as serious environmental damage [84]. As they have a nanoscale of 1 nm-100 nm, nanofertilizers have demonstrated excellent results at optimum concentrations, allowing them to penetrate plant leaves, which are the basic units for gas exchange, photosynthesis, and transpiration [85,86] as well as to reduce nutrient requirements and increasing plant productivity [87]. Nanofertilizers can be sprayed on plants to avoid interactions with water, microbes, and soil (e.g., calcareous soil), as well as to boost plant parameters and yields [10,73,88]. Many researchers have concurred with these findings [89,90]. Haukioja et al. [51] found that when nitrogen was abundant, plants predominantly formed molecules with high nitrogen content, and their metabolism shifted away from carbon-containing chemicals, such as phenolics and terpenoids. Fuglier [44] discovered that fertilizing Moringa trees with nitrogen and phosphate promoted root development and leaf canopy growth. According to Liu and Lal [91], manufactured nanofertilizers increased the biomass of Arachis hypogeae L. by 15%. Fagbenro [92], Ainika and Amans [93], Ghafariyan et al. [94], Mahmoodzadeh et al. [95], and Farnia and Ghorbani [96] have found that the application of NPK compound fertilizer has a considerable impact on crop growth, chemical composition, and yield metrics. Abdel-Aziz et al. [86] found that direct exposure to nanoparticles resulted in a significant boost in all growth metrics, measured at optimal nanosolution concentrations, in wheat plants. The foliar application of nanofertilizers and conventional NPK fertilizers improved plant growth, biomass, grain, photosynthetic pigments, chemical constituents, protein content, and yield, with nanofertilizer applications [74,87,[97][98][99][100]. When compared to control treatments, Khalid and Shedeed [101] found that the foliar application of NPK resulted in the highest values of vegetative growth characteristics, such as plant height, leaf number, branch number, capsule number, herb dry weight, yield, and chemical content parameters (e.g., fixed oil percentage, total carbohydrates, soluble sugars, protein, potassium, and phosphorus content). Hasaneen and Abdel-aziz [102] discovered that applying NPK nanoparticles or nanoengineered CNTs-NPK to the leaves of French bean plants increased their growth metrics. Hagagg et al. [14] discovered that treating olive seedlings with Nano-NPK fertilizers at a concentration of 0.2% resulted in the greatest values for leaf and root metrics. Total chlorophyll, as well as N, P, and K uptake, were improved by applying Nano-NPK fertilizer. Abd El Gayed and Attia [28] discovered that NPK (20:20:20) at 4.5 g pot −1 had the greatest positive effect on vegetative growth characteristics, number of inflorescences plant −1 , chlorophyll content (SPAD), total carbohydrate, leaf N, P, and K percentages in cockscomb. The importance of these NPK fertilizers, according to Mokrani et al. [100], lies in their ability to provide the necessary nutrients for plant growth. Sarwar et al. [103] stated that NPK administration aided Moringa growth by producing plants with significantly higher larger height, leaf count, stem girth, and maximum number of branches than other treatments. Soylu et al. [104], Soleimani [105], Arif et al. [106], and Hamayun [107] discovered that foliar treatment of nitrogen, phosphorus, and potassium in several cereal crops resulted in rapid vegetative development, as well as significant increases in the number of leaves, plant height, thousand-grain weight, and yield. Jubeir and Ahmed [108] discovered that employing a nanofertilizer enhanced the dry matter and chlorophyll content of all leaves. Clearly, these treatments improved the vegetative growth date palm and flowering. Alzreejawi and Al-Juthery [109] discovered that Nano-NPK (12-12-36) spray was significantly superior in terms of leaf chlorophyll content, plant height, stem diameter, biological yield, grain yield, and harvest index. The fixation of phosphatic fertilizers in alkaline soils due to calcareousness is one of the key challenges that can reduce maize and soybean yields, according to Rafiullah et al. [110].

Effects of Vermicompost-NPK Combination Treatments on Moringa oleifera Tree Yield Growth Parameters, and Chemical Components
Despite the vital role of foliar NPK administration in the quick uptake and translocation and its beneficial impact on growth and yield, foliar fertilization cannot completely substitute for nutrients from the roots. It can only be utilized to reduce the amount of fertilizer applied to the soil [111]. To address this gap, organic amendments, such as adding vermicompost and foliar spraying of Nano-NPK under calcareous soil conditions, are appropriate techniques that can boost the development, yield, and chemical content of Moringa oleifera trees. As a result, the maximum mean values of the two combination treatments T18 and T21 were those for plant height, stem diameter, number of main branches per tree, number of leaves per branch, fresh and dry weight of leaves, yield of fresh leaves per tree and per hectare, yield of dry leaves per tree and per hectare, number of inflorescences per tree, fresh and dry weight of inflorescences, yield of fresh inflorescences per tree and per hectare, yield of dry inflorescences per tree and per hectare, total chlorophyll, leaf soluble protein, vitamin C, phosphorus and potassium contents in combination with minimum mean values of total phenolic content, flavonoid content, and antioxidant activity in both seasons considered in the study. Combining organic and inorganic fertilizers has important consequences for plant growth as well as soil chemical and biological features [112,113]. As a result, employing vermicompost, either alone or in combination with mineral fertilizers has a positive effect on plant development and yield [114]. Our findings were similar to those of Bajracharya et al. [115], Bhattarai and Tomar [116], Thakur and Uphoff [117], Zhao et al. [118], Prativa and Bhattarai [119], and Ghimire et al. [120], who all observed that using vermicompost in combination with NPK produced the best results in terms of plant growth and production.

Materials and Methods
This study was conducted in an open field of a private farm in El-Amiriya, Alexandria Governorate, Egypt, during the two consecutive seasons of 2018/2019 and 2019/2020, in order to investigate the effect of organic and inorganic fertilization on the growth and chemical composition of Moringa oleifera trees.

Plant Material
Moringa oleifera seeds were planted in February 2018 and February 2019. Distances between rows and within plants in rows were 1 m, respectively. Pest management and other agricultural measures (e.g., irrigation) were used when necessary and as indicated.

Treatment
During February-March 2018/2019 and 2019/2020, the experiment was set up as a split plot arranged in Randomized Complete Block Design (RCBD) with three replicates. The main plots received organic fertilization in the form of a ground dose of vermicompost, whereas the subplots received mineral and Nano-NPK fertilization of Moringa oleifera plants (19:19:19). Vermicompost fertilization was applied to the main plot. NPK fertilization was put in the subplot. All feasible combinations of the two factors evaluated were tested ( Table 10). The experiment comprised 21 treatments consisting of a mix of vermicompost ground addition (0, 10, 20, 30, 40, 50, and 60 ton ha −1 vermicompost) and spraying NPK fertilization (0, 2 g L −1 mineral-NPK and 2 g L −1 Nano-NPK). Before ten days from planting, the associated amount of vermicompost was added. The 2 g L −1 NPK was used as a ground dose, while the 2 g L −1 Nano-NPK was used as foliar application. After two weeks, all plants treated with NPK fertilization received one application per week up until six weeks after planting. This was increased to twice a week, until completion of the trial. In addition, Tween 80 (0.01%) was utilized as a wetting agent. Plants that had not been treated with NPK (NPK control) were sprayed with distilled water and Tween 80. Table 10. All different combination treatments of vermicompost and NPK fertilization used.

Treatments
Main-Plot Sub-Plot

Nano-NPK Preparation
In a 2 L glass beaker, 400 g of 19:19:19 NPK mineral fertilizer was weighed, then 550 mL of distilled water was poured in and swirled until completely dissolved. The clear solution was then heated to 50 • C, after which 50 g of citric acid was added with vigorous stirring for 15 min. Potassium hydroxide was gradually added until the necessary pH was reached. The clear solution changed to a milky look when potassium hydroxide was added, demonstrating the conversion to nanoparticle size. The used concentration was calculated based on the amount of mineral NPK used in the Nano-NPK process. In the first and second seasons, seeds were planted on 1 February. On one side of the row, seeds (three seeds hill −1 ) were sown. The seedlings were trimmed to one plant per hill after 30 days. The plots were weeded as often as feasible every two weeks. Tables 11 and 12 provide the physical and chemical parameters of the vermicompost and soil samples, as determined by [121,122].

. Growth and Flowering Parameters
A sample of five plants was taken at random from each replicate (i.e., fifteen plants from every treatment), in order to measure the following growth parameters: Plant height (cm), stem diameter (mm), number of main branches per tree, number of leaves per branch, fresh and dry weight of leaves (g), yield of fresh leaves (g tree −1 and kg ha −1 ), yield of dry leaves (g tree −1 and kg ha −1 ), number of inflorescences per tree, fresh and dry weight of inflorescences (g), yield of fresh inflorescences (g tree −1 and kg ha −1 ), and yield of dry inflorescences (g tree −1 and kg ha −1 ).

Leaf Soluble Protein Content (mg g −1 )
Soluble protein contents of the extracts were determined using Folin-Ciocalteu reagent, following the method described by [123].

Vitamin C (mg g −1 dry weight)
Vitamin C in leaves was determined according to the method described by [124] The antioxidant activities of different samples were determined using 2-diphenyl-1picrylhydrazyl radical (DPPH) [127]. The extract concentration (µg mL −1 ) providing 50% of antioxidant activities (IC 50 ) was calculated by plotting the inhibition percentage against extract concentration in a graph.

Phosphorus Percentage (P 2 O 5 )
Phosphorus percentage was determined in leaves colorimetrically as reported by [122].

Potassium Percentage (K 2 O)
Potassium percentage was determined in leaves by atomic absorption spectrophotometry following the method was described by [128].

Statistical Analysis
The experiment was set up as a split plot arranged in Randomized Complete Block Design (RCBD) with three replicates for every treatment. Vermicompost fertilization was put in the main plot. NPK fertilization was carried out in the subplot. All data from the tested treatments were subjected to analysis of variance using the SAS software [129]. The LSD test was used to compare the means of the treatments at the 5% probability level. The experiment was performed in the second year using the same methods and approaches as the first year.

Conclusions
Increasing the amount of vermicompost improved the characteristics of the Moringa oleifera tree, as well as the yield of its leaves and inflorescences. Finally, our recommended treatment for maximizing fresh and dry leaf production is treatment T21, while for the highest possible yield of fresh and dry inflorescences, treatment T18 was the best. On the other hand, the control treatment led to the maximum total phenolic content, flavonoid content, and antioxidant activity of Moringa oleifera dry leaves.

Data Availability Statement:
The data presented in this study are available within the article.