Dynamics of Agronomic Characteristics and Plant Diversity in Lemon Verbena (Aloysia citrodora Paláu) Cultivation in Greece

Abstract

Nowadays, there is an increasing negative environmental effect of using chemical fertilizer. For this reason, the use of biofertilizers is promoted in the agriculture sector. The purpose of this investigation was to carry out an evaluation of the effects of biological fertilizer (biofertilizers are organic materials that can be used to improve soil properties) use on the growth and agronomic characteristics of Aloysia citrodora. To achieve this aim, a two-year randomized complete blocks field experiment was carried out in central Greece. The experiment included four biological fertilizer levels (0, 50, 100 and 150 N kg ha⁻¹) with three replications. Plant height, dry stem, dry leaves, dry total yield and leaf area index (LAI) were measured during the two growing years. The results showed that in the first and second studied years, the maximum plant height and total dry yield were observed in the BF150 treatment. Moreover, LAI was ameliorated by applying the BF100 and BF150 treatments in both studied years. A key finding in this study is that the A. citrodora ecosystem favors herbaceous plant species richness. Also, soil factors (soil organic matter, P and K) promote positive herbaceous plant diversity within the A. citrodora ecosystem. Finally, A. citrodora could be a promising medicinal plant, cultivated under Mediterranean climatic conditions.

1. Introduction

Greece is regarded as one of the European continent’s most biologically varied countries, with a high level of endemism and plant diversity [1,2].

To put this into perspective, Greece’s flora makes up 26% of Europe’s flora, despite the country accounting for only 6% of the Mediterranean region [3].

It is common knowledge that aromatic and medicinal plants are essential to human health, environmental preservation and sustainable development [4,5]. A. citrodora Paláu is one of these plants, and provides significant ecosystem services and health benefits. Originally found in South America [3], the plant was brought to Europe by the Spanish, and currently, many nations in Latin and Central America, Southern Europe (including Greece and France), Northern Africa (including Algeria and Morocco), China and Iran are cultivating it. In Greece, it is found mainly in Central Makedonia and Thessaly [6].

A. citrodora Paláu is used as both a culinary and a medicinal herb. The Verbenaceae family, which includes 800 species and 32 genera, includes the genus A. citrodora. Aloysia triphylla (L’Hér.) Britton, Lippia citriodora Kunth, Lippia triphylla (L’Hér.) Kuntze, Verbena triphylla L’Hér. and Zappania citrodora Lam are among its botanical synonyms [7].

There are many medicinal and aromatic properties associated with this shrub. A. citrodora is an evergreen perennial shrub and a deciduous sub-shrub, and there are about 2300 species in the genus Alloysia. A warm, moist environment with plenty of sunlight is ideal for it as it becomes deciduous when exposed to frost. With an annual water need of 500 to 1.300 mm, A. citrodora favors light, sandy, medium loamy, well-drained acid, neutral, and basic alkaline (pH = 4.5–7.8) soils [8,9]. Many studies have been conducted on the relaxing, digestive and soothing effects of the lemon-scented essential oil from A. citrodora [8,9,10].

A. citrodora has also long been used as a treatment for respiratory and gastrointestinal issues. Some species have antiviral, antispasmodic, antibacterial, antioxidant and cytostatic qualities in addition to antimalarial ones [11,12,13,14]. In addition to fresh leaves, A. citrodora leaves can be added to soups and stews [15]. Numerous investigations have indicated that the therapeutic benefits associated with lemon verbena are attributed to flavonoids and essential oils [16,17]. To extract the essential oil, between 0.22% and 1.00% of A. citrodora leaves are hydrodistilled. Particle size, time of day and harvesting season all affect volatiles [18]. The literature indicates that in Greece, more attention is paid to the essential oil of A. citrodora, while its effects on parameters influencing ecosystem structure (such as biodiversity, soil properties, etc.) are neglected.

According to the statistical data of the Hellenic Ministry of Rural Development and Food, in 2019, 2020 and 2021, 1.780, 1.960 and 2.050 hectares of A. citrodora were cultivated, respectively [6]. Τhe data indicate that the cultivation of A. citrodora in Greece has an increasing trend. Not many studies have been carried out concerning the cultivation of Allysia under Greek cultivation conditions [6].

To increase the total biomass of crops, nitrogen is a crucial additional component that is commonly applied to agricultural fields [19]. Synthetic fertilizers have the potential to contaminate and pollute waterways and soil [20,21]; as a result, there is currently a movement towards replacing chemical fertilizers with biological ones. In addition to aiding in plants’ uptake of nutrients, bacteria and fungi found in organic fertilizers have the potential to significantly boost both the quantity and quality of crop production [22].

Farmers are responding to consumer concerns about food security by producing chemical-free products. By means of biological processes, biofertilizers can stimulate the elements that are beneficial to plants, increase the availability of nutrients, and improve the nutrient process in the soil. Biofertilizers work through either direct or indirect mechanisms. The former ones directly impact plant growth through processes like phosphate solubilization and nitrogen fixation. The latter ones shield plants from pathogens’ damaging effects [20,23,24,25].

The impact of the application of a biological fertilizer recommendation program in A. citrodora cultivation is lucking according to the literature [26]. The determination of its chemical oil composition is mentioned in the majority of published papers [27,28,29,30,31].

The objective of this study was to assess the effects of varying doses of biofertilizer on the agronomic traits and herbaceous plant diversity of A. citrodora in central Greece, with the aim of achieving the aforementioned goal.

2. Materials and Methods

2.1. Study Area

The field experiments were established in 2014 using A. citrodora cuttings which were obtained from a local nursery. Two growing periods (2014 and 2015) of A. citrodora plants were studied. The experiments were conducted in Velestino city (Volos, Magnesia). The studied area has a latitude of 39°38′84″ and a longitude of 22°73′62″ and is located at an altitude of 120 m above sea level (Figure 1). The area has a Mediterranean climate with hot, dry summers and cool, humid winters.

2.2. Soil Analysis

In the 1st year, two soil samples from two depths (0–30 and 30–60 cm) were collected using the appropriate soil sampler. In the 2nd year, one soil sample was collected from one depth (0–40 cm). Each soil sample consisted of five soil subsamples. The soil samples were transported to the Soil laboratory of the Institute of Industrial and Forage Crops (Larissa), air-dried and sieved using a 2 mm sieve. Soil samples were analyzed to determine the pH (1:2.5 distilled H₂O); electrical conductivity (1:5 distilled H₂O); calcium carbonate (CaCO₃) using a calcimeter; percentage (%) of sand, clay and silt using the Bouyoukos method; and organic matter with Walkley–Black method. Available P (Olsen method, analyzed with ammonium vanadomolybdate/ascorbic blue and measured in a UV spectrophotometer at 882 nm) and Exchangeable Κ (1:10 at 1M CH₃COONH₄ pH 7, analyzed in a flame photometer) were determined according to Rowell (1994) [32].

The soil was loam with pH 7.6, 1.8% organic matter and 11.5–12% CaCO₃. The physicochemical properties of the soil are presented in

Table 1. Physicochemical properties of the used soil the 1st and 2nd cultivation years.

Year	Depth	pH	Organic Matter (%)	CaCO3 (%)	Sand (%)	Silt (%)	Clay (%)	P (mg kg−1)	K (mg kg−1)
2014	0–30 cm	7.6	1.8	11.5	38	15	47	40	172
2014	30–60 cm	7.6	1.8	12	40	13	47	35	170
2015	0–40 cm	7.5	1.83	13	39	14	47	43	175

.

2.3. Meteorological Data

The meteorological data are presented in Figure 2. Total precipitation levels were 162.3 mm and 264.5 mm from May to September in the 1st and 2nd years, respectively. The higher rainfall events were in May 2015 (62.5 mm) and in September 2015 (100 mm). On average, over the growing season, the air temperature of the first year was 3 °C higher than that of the second one.

2.4. Field Experiment

A two-year field experiment was established, and the experimental method used was randomized complete blocks. Before the transplant, the plants were rose for three months in polyethylene bags. The transplant was carried out on 3 May 2014. The field consisted of 12 plots. Each plot was 3.6 m² in size (180 × 180 cm²). In every plot, 16 plants were transplanted in 4 rows, and the distance between plants and distance between rows were both 60 cm. Additionally, there were one-meter corridors between the plots (Figure 3). The experiments included four nitrogen treatments using a biological fertilizer (6-0.5-0.3), BF0: 0 kg ha⁻¹, BF50: 50 kg ha⁻¹, BF100: 100 kg ha⁻¹ and BF150: 150 kg ha⁻¹. The fertilizer was manually applied at the base of plants. The composition of the biological fertilizer was as follows: 85% organic matter, 6% total N, 0.5% P₂O₅ and 0.3% K₂O (named Biosol). Also, during the experiments, the plants were watered according to their needs so that the plots maintained a constant moisture level, using a drip irrigation system.

In total, there were 4 treatments with three replicates each, and a total of 192 plants were transplanted in the field.

Plant height, dry stem weight, dry leaf weight, dry total yield and leaf area index were measured during the two growing years. The plant height of each plot was calculated from the average of five random plants. Then, these five plants were harvested by hand at 10 cm above the soil surface and immediately weighed to record the fresh total weight, using a portable scale. Furthermore, the plants were separated into leaves, flowers and stems, and each edible part was weighed. Then, the plants were transported to the Lab for further measurements. The plant tissue of each plot was dried at 40 °C until constant weight. Each plant part and the total biomass were weighed so that the dry weight could be calculated.

LAI measurements were performed during three different cutting periods from two plants of every different plot. Leaf area index was determined using an automatic LI-COR (model LI-3000A). The measured agronomic data are summarized in

Table 2. Agronomic data of Aloysia citrodora cultivation in two growing years.

	Velestino
	2014	2015
Date of transplant	3 May 2014	-
Height	29 September 2014	29 August 2015
Fresh and dry weight	30 June 2014, 28 July 2014, 29 September 2014	20 May 2015, 2 July 2015, 29 August 2015
LAI measurement	30 June 2014, 28 July 2014, 29 September 2014	20 May 2015, 2 July 2015, 29 August 2015
Date of harvest	30 June 2014, 28 July 2014, 29 September 2014	20 May 2015, 2 July 2015, 29 August 2015

.

2.5. Sampling of Herbaceous Plants

The sampling of herbaceous plants was conducted during May–June in 12 plots of 0.25 m², every year. In each plot, herbaceous plant species richness and density in organic Aloysia citrodora were recorded [33]. Also, 12 soil samples were collected using the appropriate soil sampler from depth 0–30 cm. The physicochemical properties of the studied soil samples for the two years are presented in

Table 3. Physiochemical properties of the 12 soil samples for the 1st studied year (2014).

2014	pH	Organic Matter	CaCO3	Sand	Silt	Clay	P	K	Mg
Units		%					(mg kg−1)
Treatment
1	7.6	1.80	11.5	38	15	47	40	172	326
2	7.6	1.80	12	40	13	47	38	170	330
3	7.5	1.71	13	39	14	47	43	175	335
4	7.7	1.79	11.1	41	15	44	41	176	320
5	7.6	1.70	10	40	15	45	40	172	322
6	7.4	1.61	12	42	16	42	36	168	328
7	7.5	1.80	12.5	42	15	43	44	173	321
8	7.5	1.70	13	40	16	44	45	174	325
9	7.7	1.80	13.5	43	15	42	42	170	329
10	7.6	1.69	11.4	41	14	45	43	174	327
11	7.5	1.70	11.5	41	15	44	40	175	326
12	7.6	1.80	13	38	16	46	39	172	330

(2014) and

Table 4. Physiochemical properties of the 12 soil samples for the 2nd studied year (2015).

2015	pH	Organic Matter	CaCO3	Sand	Silt	Clay	P	K	Mg
Units		%					(mg kg−1)
Treatment
1	7.5	1.82	12	40	16	44	40	171	328
2	7.7	1.83	12.5	41	15	44	38	171	331
3	7.6	1.73	13.2	40	15	45	43	174	334
4	7.7	1.81	11.5	42	15	43	41	175	321
5	7.5	1.72	10.5	39	14	47	39	172	325
6	7.5	1.64	12	40	13	47	36	169	329
7	7.5	1.81	12	41	15	44	44	174	322
8	7.6	1.72	13.5	42	16	42	45	175	326
9	7.6	1.82	13	42	15	43	42	171	330
10	7.5	1.72	11.5	39	17	44	44	173	326
11	7.5	1.71	11.5	41	16	43	40	174	327
12	7.5	1.81	13.5	38	15	47	39	173	328

(2015).

2.6. Statistical Analysis

The Shannon index (SH) is calculated for any sample population as follows:

$$H^{\mathrm{’}}=-\sum _{i=1}^s{P}_i\mathrm{I}\mathrm{n}{P}_i$$

(1)

where H′ is the species diversity index, s is the number of species, and p_i is the proportion of individuals of each species belonging to the species of the total number of individuals [34,35,36] (for a detailed description for this index, see Seaby and Henderson [37]). Also, correlation analyses between the measured variables (soil organic matter (%); pH; CaCO₃; texture—clay, silt and sand; P; K; and Mg) and SH in an organic L. citriodora were carried out using Pearson correlation coefficients.

The statistical analyses for the data (plant height, dry plant biomass, LAI and Pearson correlation coefficients) were performed using “STATGRAPHICS Centurion” software package (v.18.1.01, Statgraphics Technologies, Inc., The Plains, VA, USA) with the LSD test at a level of significance of 95% (p < 0.05).

3. Results

3.1. Plant Height

Figure 4 shows the results regarding the height of the plants when they were measured during the harvest on 29 September 2014 and the second final harvest on 29 August 2015. As shown in Figure 3, the maximum height of the plants during the first year and second year reached values of 51.8 and 61.2 cm in the BF150 plots. Fertilization seems to have had positive effects on plant height in the first and second growing periods. Moreover, a statistically significant difference was observed between the BF0 and the other treatments (BF50, BF100 and BF150). Furthermore, in the first year, the application of BF150 fertilizer increased the plant height by 5.14% and 18.33% compared to BF100 and BF50, respectively. In the second year, the increases were 1.09% and 16.08%.

3.2. Dry Plant Biomass

Table 5. Effects of the different fertilization treatments on dry stem, dry leaf and total dry weight (kg ha⁻¹) of Aloysia citrodora cultivated in the two growing years.

	2014			2015
Treatment	Dry Stem Weight, kg ha−1	Dry Leaf Weight, kg ha−1	Total Dry Weight, kg ha−1	Dry Stem Weight, kg ha−1	Dry Leaf Weight, kg ha−1	Total Dry Weight, kg ha−1
N0	583.33 a*	576.67 a	1160.00 a	1245.83 a	1174.50 a	2420.33 a
BF50	723.33 b	713.33 b	1436.67 b	1391.33 b	1406.17 b	2797.50 a
BF100	830.00 c	855.00 c	1685.00 b	1624.50 c	1609.33 c	3233.83 b
BF150	955.00 d	990.00 d	1945.00 c	1952.83 d	1983.00 d	3935.83 c
LSD0.05	24.768	21.683	34.185	28.949	32.228	48.619

* Different letters in each column denote statistically significant difference in means according to the LSD test with a 95% significance level (p < 0.05).

shows the dry weight results of the stems, leaves and total dry biomass, as measured in 2014 and 2015. In 2014, three cuttings of plants were taken on 30 June 2014, 28 July 2014 and 29 September 2014, specifically 57, 85 and 146 days after planting. In 2015, plants were harvested three times on 20 May 2015, 2 July 2015 and 29 August 2015, 382, 424 and 511 days after planting. In 2014, the maximum amount of dry stem (955 kg ha⁻¹), dry leaf (990 kg ha⁻¹) and total dry biomass (1945 kg ha⁻¹) was observed under BF150 fertilization. In 2015, the fertilization that gave the highest total dry weight was the BF150 treatment, with a yield of 3935.83 kg ha⁻¹, followed by BF100 and BF50 with 3233.83 and 2797.50 kg ha⁻¹, respectively. Furthermore, in the two studied years, a statistically significant difference was noticed between the BF150 level and other treatments.

3.3. Leaf Area Index

The results of the LAI are illustrated in Figure 5. Three measurements of LAI were conducted, in the first year on 30 June 2014, 28 July 2014 and 29 September 2014 and the in second year on 20 May 2015, 2 July 2015 and 29 August 2015. In the first growing year, higher LAI values were observed with BF150 application, and a significant increase in the LAI values of the BF150 plots was noticed, which were 62.55%, 47% and 39.49% in the first, second and third measurements, respectively, compared to BF0. In the second growing year, the BF100 and BF150 treatments resulted in the highest values of LAI, and between these fertilizations, there was no statistically significant difference. Moreover, in the second year, the LAI value increased by 27.18% in the BF100 treatment.

3.4. Herbaceous Plant Composition

In total, 20 plant species in the A. citrodora ecosystem were recorded in the study area (

Table 6. Herbaceous plant species in Aloysia citrodora.

Herbaceous Plant Species	Family	Aloysia citrodora Ecosystem
Aegilops geniculata Roth.	Poaceae	+
Amaranthus deflexus L.	Amaranthaceae	+
Anthemis arvensis L.	Asteraceae	+
Arctium lappa L.	Asteraceae	+
Avena sterilis L.	Poaceae	+
Bellis perennis L.	Asteraceae	+
Calystegia sepium (L.) R. Br.	Convolvulaceae	+
Capsella bursa-pastoris (L.) Medik.	Brassicaceae	+
Chenopodium album L.	Chenopodiaceae	+
Fumaria officinalis L.	Fumariaceae	+
Glaucium flavum Crantz	Papaveraceae	+
Heliotropium europaeum L.	Boraginaceae	+
Lamium amplexicaule L.	Lamiaceae	+
Lolium perenne L.	Poaceae	+
Polygonum aviculare L.	Polygonaceae	+
Sinapis arvensis L.	Brassicaceae	+
Sonchus arvensis L.	Asteraceae	+
Sorghum halepense (L.) Pers.	Poaceae	+
Stellaria media (L.) Vill.	Caryophyllaceae	+
Veronica persica Poir.	Veronicaceae	+
Total		20

). The most frequently occurring plants were Avena sterilis L. (family: Poaceae) (status: native; chorology: Mediterranean–SW Asian; life-form: therophyte; habitat: agricultural and ruderal habitats) and Chenopodium album (family: Chenopodiaceae) (status: native; chorology: cosmopolitan; life-form: therophyte; habitat: agricultural and ruderal habitats) in the Aloysia triphylla L. ecosystem (Figure 6).

3.5. Environmental Factors Affecting the Shannon Plant Diversity Index

In our study, the Pearson correlation coefficients (

Table 7. Pearson correlation coefficients of soil parameters with the Shannon diversity index.

Soil Parameters	Shannon Diversity Index
Soil organic matter	0.83 *
pH	0.15
CaCO3	0.13
Texture—clay	0.23
Texture—silt	0.20
Texture—sand	0.19
P	0.92 *
K	0.81 *
Mg	0.17

* denotes significance level at 0.05 probability.

) showed that there were soil parameters, such as soil organic matter (SOM), phosphorus (P) and potassium (K), on which the SH plant diversity index depended significantly for organic A. citrodora.

4. Discussion

4.1. Plant Height

In the first year, the plant height ranged from 32.7 cm (control) to 51.8 cm (BF150), while in the second year, the height was between 40.7 (control) and 61.2 cm (BF150). The BF100 level had a significant increasing effect on plant height (18.73%) in the second year, while BF150 fertilization increased the plant height by 15.26% compared to the first year. Kassahun et al. [39] found that the A. citrodora plants’ height varied from 61.67 to 87.14 cm, results that are in disagreement with our study. In accordance with our findings, Mohammadi et al. [40] noticed that the use of biofertilizer in A. citrodora cultivation had positive effects on plant height. According to the literature, biological fertilizers can improve plant growth by improving soil fertility [41]. The beneficial effects of biofertilizers have been investigated in many other medicinal and aromatic plants [42,43]. Molla et al. [44] mentioned an increase in plant height in Salvia officinalis when biofertilizers were applied. Moreover, Valiki and Ghanbari [45] stated that biofertilization in Rosemary cultivation increased the height of plants.

4.2. A. citrodora Total Dry Yield

The total dry production (stem, leaf) was increased after the use of nitrogen in the biological fertilizer. In the second year, an average increase of 49.8% in total biomass was observed in all the treatments. This increase was expected, because A. citrodora is a perennial scrub which comes to full production after the second year of cultivation. It is remarkable that the BF150 treatment provoked the most effective increase in the second year (50.58%) compared to the first. Until now, only a few investigations have studied the use of organic fertilization in A. citrodora and its positive effects on dry biomass [23,27]. Afonso et al. [27] mention that the application of a biological fertilizer in A. citrodora cultivation from 0 to 100 kg N ha⁻¹ increased the leaf and total yields, while between 100 and 150 kg N ha⁻¹, there was stabilization in the yield. Studies show that the use of biofertilizer (Azospirillum and Azotobacter) increases Salvia plants’ dry weight [46].

4.3. LAI

The BF100 and BF150 biological fertilizer levels had a significantly positive effect on leaf area index in the second studied year. Specifically, in the second year, the increase in LAI upon using the BF100 fertilizer reached an average value of 27.18%. Very few publications are found to have studied the impact of biofertilization on the leaf area index of A. citrodora. Martinos et al. [47] mentioned that the leaf area index increased when 100 kg ha⁻¹ of a biofertilizer was applied compared to 0 and 50 kg ha⁻¹ in A. citrodora cultivation in experiments which were conducted in Aghialos in Central Greece. Molla et al. [44] measured the LAI in Salvia officinalis cultivation, and the results showed that the highest dose of biofertilizer resulted in the highest value of LAI.

4.4. Herbaceous Plant Composition

The agricultural landscape is a cultural landscape. Agroecosystems are the basic components of rural landscapes. There are large numbers of flora in agroecosystems, and those systems are considered agricultural systems that possess high ecological value for biodiversity (high-nature-value farming systems). The most frequently occurring plants were Avena sterilis L. and Chenopodium album in the A. citrodora ecosystem. These plant species are characteristic of agroecosystems, according to Dimopoulos et al. [38]. Several suitable regions of Greece have already been invaded by Chenopodium album and Avena sterilis. The most important factors explaining herbaceous plant species composition, based on [48], are management practices and environmental factors. It is noteworthy that plants are an important indicator of environmental health since they connect the ground to the air. Particularly, they draw most of the data they need from the ground, but their peaks are also directly related to the air because their components make up gas collectors. As a result, comparing the chemical composition of plants that grown in unhealthy environments with that of plants that grow in healthy environments is an important method of determining contamination in plant growth areas. According to the literature, Chenopodium album is an indicator plant in the A. citrodora ecosystem, as it indicates soil nitrogen and humus levels [49], which is very important for farmers regarding crop management decision making.

4.5. Environmental Factors Affecting the Shannon Plant Diversity Index

The physical characteristics of soil are a key factor that defines soil’s own physical consistency, a physical consistency that is actively influenced by biological processes, while chemical elements are used to specify soil properties [50,51,52]. In our study, despite the modest differences in OM, P and K contents, it was found significant correlations with plant diversity. SH plant diversity correlated positively with soil organic matter (SOM), phosphorus (P) and potassium (K). This is probably because organic matter in soils preserves nutrients, upgrades the nutrient circle, determines soil composition, improves water permeability, decreases soil density, prevents rapid changes in soil pH, serves as a power source for microorganisms and increases the rate of assimilating copper, magnesium and zinc into the soil; therefore, all of the above affect soil composition and plant diversity [53]. It is noteworthy that organic soil provides important nutrients, such as phosphorus and potassium, used by plants in large quantities for their growth and survival. Soil phosphorus (P), being an organic and inorganic substance, it is found in soils, water and most living organisms. Many P chemical mixtures are in harmony and extend from solution P (absorbed by plants) to stable, unstable or even unobtainable compounds (the most common). As the most important nutrient for plants, phosphorus plays a crucial role. Phosphorus plays many roles in plants, but the biggest one is storing and transferring energy [46,48,49,50,51,52,53,54,55]. Furthermore, potassium (K) is an important element in determining soil fertility and plant diversity. Based on its accessibility to plants in soil solution, potassium is separated into interchangeables and irreplaceables and exists in soil crystal lattices [56,57]. Among its many functions, it maintains plant turgor, stomatal movement, cell expansion, pH, phloem transport and protein synthesis. Maestre et al. [58] and Korol et al. [59] stressed the importance of P cycling with regard to plant diversity. Potassium increases the resistance of plants to dry climates, such as in the Mediterranean zones, and P provides energy for all biological reactions, and therefore, both elements contribute to the increase in biodiversity [60].

5. Conclusions

Generally, BF100 application led to almost the same results in the plant height and dry weight of the edible parts of the cultivation of A. citrodora compared to BF150. This means that the best biofertilizer for A. citrodora cultivation is the BF100 nitrogen level rather than BF150, although the results for BF150 were a little bit better. The use of BF100 fertilizer can positively impact the agronomic characteristics of A. citrodora with minimum cost, not only for the producers but also for the environment generally.

A. citrodora ecosystems provide a variety of functions and services that are beneficial to humans and animals. There is a significant finding in this study that soil factors (soil organic matter, P and K) promote positive herbaceous plant diversity within the A. citrodora ecosystem. These results are crucial for understanding the ecology and dynamics of this ecosystem. As aromatic and medicinal plants have beneficial effects, as well as contributing to the development of several sectors like medicine, there is a need to continue their study in the future. It is notable that the data from this study are relevant to health-care program development, aromatherapy, phytotherapy, economic agricultural policy development, alternative food programs and ethnobotany.

The climate and physicochemical properties of the soils in Greece favor the growth of aromatic medicinal plants that can produce products of excellent quality, even if cultivated in mountainous and semi-mountainous areas. There are many such lands in our country, and the cultivation of these plants can considerably improve the income of rural residents.