Productivity and Quality of Chamomile (Chamomilla recutita (L.) Rausch.) Grown in an Organic System Depending on Foliar Biopreparations and Row Spacing

Abstract

The study involved a field experiment conducted on two cultivars of chamomile (‘Złoty Łan’ and ‘Mastar’) in the climatic and soil conditions of the central Lublin region (Poland) during the years 2016–2018. The experiment was designed to determine the effects of three foliar biological preparations (growth stimulant Bio-algeen, fertilizer Herbagreen Basic, and Effective Microorganisms applied as EM Farming spray), which were applied once or twice, on the yield and quality of herbal raw material of chamomile grown under organic conditions. Chamomile was grown at different row spacings (40 cm and 30 cm). The biopreparations (in particular Herbagreen Basic) had a positive effect on chamomile yield (about 10–11% in comparison with control treatment) and yield attributing characters (plant height, number of branches, and inflorescences per plant) as well as on the quality parameters. The EM Farming had a minimal influence on the quantity characteristics studied, but it beneficially affected essential oil and chlorophyll content. The biopreparations had a more favorable effect when they were applied twice. The wider row spacing of chamomile (40 cm) promoted higher yields (about 18%) compared to 30 cm. The narrower spacing (30 cm), however, contributed to better quality characteristics of herbal raw material. The study confirmed much higher productivity and quality of the cultivar ‘Złoty Łan’ compared to cv. ‘Mastar’ (about 15%). Significant interactions of experimental factors concerned mainly the formation of the essential oil content in herbal raw material (the most advantageous was the ‘Złoty Łan’ cultivar sown at a row spacing of 30 cm with the use of Herbagreen Basic biopreparation twice).

1. Introduction

Chamomile (Chamomilla recutita L. Rausch) is a very popular herbal plant that is grown worldwide. Due to its rich chemical composition and mild effects, chamomile finds application in many fields. It exhibits anti-inflammatory, spasmolytic, and disinfectant activity. Combined with other herbs, it has sedative and antipyretic effects [1,2]. Breeding work has led to the development of several chamomile cultivars with a habit that enables their mechanical cultivation, but primarily with a high content of active substances in the essential oil, especially one of the sesquiterpenes—α-bisabolol (mainly its oxides). Apart from its anti-inflammatory activity, this compound can also induce the apoptosis of leukemic leukocytes [3,4]. The essential oil content in chamomile raw material is 0.24–1.9%. Flavonoids, which are strong antioxidants, are another important active substance [5]. The cultivation of herbs can be a good choice for many farmers, in particular, on organic farms [6]. Improvement of the agronomy of herbal plants, especially chamomile, which is very popular in Poland and across the world, is still topical, in particular in the context of organic and environmentally friendly methods. Some research studies show that biopreparations (growth stimulators, foliar fertilizers) may have a positive effect on the productivity and raw material quality of these plants, while effective microorganisms to a lesser extent [7,8,9,10,11].

Organic farming does not use NPK mineral fertilizers, and therefore foliar fertilizer Herbagreen Basic can be applied as an alternative or supplemental fertilization. Advanced turbine technology is used to manufacture this latest-generation compound foliar fertilizer using natural minerals. It provides fertilization and stimulation of plants grown under field and greenhouse conditions and also enhances plant resistance. This biofertilizer supplies plants with various nutrients such as highly available and non-toxic forms of calcium, silicon, magnesium, iron, titanium, manganese, and other elements. It enhances the resistance of plants, detoxifies them due to an increased antioxidant content in the cell sap, and decreases their susceptibility to pest attacks. The application of this foliar fertilizer also results in the stimulation of photosynthesis because additional CO₂ is provided to the intercellular cavities [12].

Bio-algeen, a growth biostimulant that is allowed for use in organic farming, is an extract from sea algae. This bioproduct activates metabolic processes in crop plants, increases their resistance to fungal and viral pathogens, and provides better absorption of soil nutrients by plants. It has been shown that Bio-algeen has a beneficial effect on the yield and quality of tomato fruits [13] as well as on the yield of common basil [14] and garden thyme raw material [15].

The application of Effective Microorganisms can also provide higher yields and better quality of herbal raw material. Microbiological preparations (e.g., EM Farming) have been shown to produce positive results (increased yield and a higher content of important chemical components) in the cultivation of some vegetable and herbal plants [7,16,17]. Microbiological preparations contain inter alia, lactic bacteria (Lactobacillus casei, Streptococcus lactis), photosynthetic bacteria (Rhodopseudomonas palustris, Rhodobacter sphaeroides), yeasts (Saccharomyces albus, Candida utilis), actinobacteria (Streptomyces albus), and mold fungi (Aspergillus oryzae, Mucorhiemalis) [18].

Some authors [10,19,20] draw attention to the important role of row spacing, which is often dependent on the adopted method of plant tending, fertilization, and crop protection in growing herbal plants in order to obtain satisfactory yields. Nonetheless, existing research demonstrates that the influence of row spacing used may vary—it has a different effect on biometric characteristics and a different effect on quality parameters of herbal raw material [21,22]. The literature on the subject lacks comprehensive scientific studies on the ecological cultivation of chamomile (simultaneous comparison of the effect of using various foliar biopreparations, different row spacing, as well as chamomile cultivars). It was assumed to obtain statistically significant interactions between the introduced experimental factors.

Taking into account the above premises, the aim of this study was to determine the yield structure and some quality parameters of herbal raw material of the chamomile cultivars ‘Złoty Łan’ and ‘Mastar’ grown at two row spacings—30 cm and 40 cm—depending on the biopreparations (growth biostimulator, foliar fertilizer, effective microorganisms) applied once or twice. The research hypothesis was that the foliar sprays would have a beneficial effect on the yield and quality of chamomile with a 40 cm raw space. Moreover, it was assumed that the double application of biopreparations would have a better effect on the productivity and quality of chamomile than single spraying. Significant differences in the yield-generating effect of the compared biopreparations were also expected.

2. Materials and Methods

2.1. Experiment Design and Field Management

From 2016 to 2018, field experiments involving the cultivation of chamomile (Chamomilla recutita (L.) Rausch.) were carried out in the village of Fajsławice (51.0952° N, 22.9632° E), Lubelskie Voivodeship, Poland. A split-block design was used in the experiment, and it was conducted in triplicate. The experimental blocks consisted of treatments with two chamomile cultivars, and they comprised alternately arranged plots in which two different row spacings of chamomile were used. Seven foliar spray fertilization treatments were tested, and they were randomly allocated to two chamomile cultivars and two row spacings used in this study. There were 84 plots in total, whereas a single plot area was 9.0 m² (each plot was a 1.5 m × 6.0 m rectangle). The traits investigated in this study were determined for each of the 84 experimental plots. Chamomile was grown on podzolic soil classified as good rye soil complex (soil class III). Crops were organically grown in the experimental field (no synthetic mineral NPK fertilizers and crop protection chemicals—herbicides, fungicides, and insecticides—were used).

Organic farming had previously been used in this experimental field since 2010, thus over a period of 6 years before the experiment was set up. Winter rye, spring vetch, potato, spring barley, white mustard, and oat were organically grown in this field during the period 2010–2015. During the entire period of 2010–2018, this field was supervised by a certification body (Polish Society of Organic Farming ‘Eco-guarantee’), and it is still under this organization’s supervision, as well as holds an Organic Farming Certificate. A 180-m ‘buffer zone’ (with organically grown lacy phacelia, red clover, and oat) surrounded this organic farming experiment, and there was an 800-m distance between experimental plots and the nearest traffic artery. Over the study period, soil had slightly acidic pH (in 1 M KCl = 6.2–6.4) and a medium content of available macronutrients (P = 77.8–78.2; K = 83.4–85.2; Mg = 30.7–31.4 mg kg⁻¹). The soil humus content was at a level of 1.40–1.42%. The experiments in growing the above-mentioned chamomile cultivars included the following factors:

I. Chamomile cultivars

a. ‘Złoty Łan’—a commonly grown cultivar;

b. ‘Mastar’—a new and less popular cultivar.

II. Foliar sprays:

A—Without application of foliar sprays (control treatment);

B—Foliar spray Herbagreen Basic—(10 g in 1.0 L of water; 2.0 kg ha⁻¹);

C—Foliar spray Bio-algeen S90—(4.0 mL in 1.0 L of water; 0.8 L ha⁻¹);

D—Foliar spray Effective Microorganisms—EM Farming—(60.0 mL in 1.0 L of water; 12.0 L ha⁻¹);

E—Double application of the foliar spray Herbagreen Basic—(2 × 5 g in 1.0 L of water; 2.0 kg ha⁻¹);

F—Double application of the foliar spray Bio-algeen S90—(2 × 2.0 mL in 1.0 L of water; 0.8 L ha⁻¹);

G—Double application of the foliar spray Effective Microorganisms—EM Farming— (2 × 30.0 mL in 1.0 L of water; 12.0 L ha⁻¹).

III. Row spacing and seeding density:

1. Row spacing—40 cm (2.0 kg ha⁻¹);

2. Row spacing—30 cm (2.5 kg ha⁻¹).

In the result tables, individual variants of biopreparation use are marked with the following abbreviations: A— No foliar sprays application (control treatment); B—Foliar spray Herbagreen Basic; C—Foliar spray Bio-algeen S90; D—Foliar spray Effective Microorganisms—EM Farming; E—Double application of the foliar spray Herbagreen Basic; F—Double application of the foliar spray Bio-algeen S90; G—Double application of the foliar spray Effective Microorganisms—EM Farming.

Throughout the study period, the previous crop was white mustard grown for green manure. A mineral fertilizer allowed in organic farming, Humac Agro, was used for soil fertilization before sowing. The chemical composition of fertilizer Humac Agro (nutrient content on a dry weight basis) is as follows: moisture content = 20%, humic acid = 62%, N = 10.3 g kg⁻¹. P = 1.05 g kg⁻¹. K = 1.18 g kg⁻¹. Ca = 16.80 g kg⁻¹. Na = 12.80 g kg⁻¹. Fe = 14.50 g kg⁻¹. Zn = 64.0 mg kg⁻¹. Br = 77.0 mg kg⁻¹. Cu = 19.0 mg kg⁻¹. Se = 6.0 mg kg⁻¹.

Humac Agro (content N = 10.3 g kg⁻¹, i.e., 1.03%) was applied in the amount of 170 kg ha⁻¹ (1751 g N kg⁻¹), which was one-tenth of the amount of nitrogen (with traditional mineral fertilization with N—ammonium nitrate 34%) applied in agricultural practice at the dose of 50 kg ha⁻¹ in the conventional system. An ‘economical dose’ of Humac Agro fertilization was used to show more clearly the effect of the biopreparations used on the productivity and quality of chamomile.

In the third 10 days of April, chamomile was seeded directly into the soil by means of a hand seeder equipped with a press wheel. The seeding rate was 2.0 kg ha⁻¹ (a 40 cm row spacing; distance between plants in a single row—10 cm; plant population in an area of 1 ha—about 200,000)—2.5 kg ha⁻¹ (a 30 cm row spacing; plant distance in a single row—8 cm; plant population in an area of 1 ha—about 240,000). Mechanical weed control was used, and weeds were removed using a weeder at the 3–5 leaf stage of chamomile. Application of the foliar sprays (treatments B–G) was carried out with a field sprayer at a pressure of 0.25 MPa. Double application of the sprays was made at the 2–3 leaf stage of chamomile and the 5–7 leaf stage (after weeds were mechanically removed), whereas a single application was carried out at the 5–7 leaf stage of chamomile.

Table 1. Components of the sprays used in the experiment.

Name of Spray	Spray Composition *
Bio-algeen S90	Sea algae extract containing 90 groups of chemical compounds, incl. vitamins, amino acids, alginic acid and other unidentified active ingredients in seaweed; main elements are: nitrogen—0.02%, potassium—0.096%, phosphorus—0.006%, magnesium—0.021%, calcium—0.31%, and iron—6.3 mg kg−1, boron—16 mg kg−1, zinc—1.0 mg kg−1, copper—0.2 mg kg−1, manganese—0.6 mg kg−1; additionally, the extract contains molybdenum and selenium
Herbagreen Basic	Calcium oxide (CaO)—36.7%, silicon dioxide (SiO2)—17.0%, iron trioxide (Fe2O3)—3.4%, magnesium oxide (MgO)—2.4%, titanium dioxide (TiO2)—0.5%, potassium oxide (K2O)—0.5%, sodium oxide (Na2O)—0.5%, sulfur trioxide (SO3)—0.4%, phosphorus pentoxide (P2O5)—0.5%, manganese oxide (MnO)—0.1%; and trace amounts of boron (1), cobalt (13), copper (26), zinc (34) (mg kg−1 DM).
EM Farming	Anaerobic organisms releasing free, chemically uncombined oxygen into environment during metabolic processes (photosynthetic bacteria, action bacteria, lactic acid bacteria, fermentation fungi, yeasts)—information concerning the percentages of individual microorganism strains included in the spray is the manufacturer’s secret (protected by a patent) and such information cannot be found in any available data sheets

* It should be emphasized that, in accordance with the research assumptions, biopreparations (due to the very diverse chemical and biological composition) played the role of supporting the growth of chamomile plants, making them resistant to possible adverse soil and climatic factors, the activity of pests and stimulating the physiological and biochemical functions of plants. This takes place, among others, by modifying the architecture of the root system, increasing the efficiency of nutrient use (biopreparations indirectly contribute to increasing yields). On the other hand, nourishment was provided to the plants by the Humac Agro fertilizer described in the previous part of the methodology.

presents the specific composition of the biopreparations applied in this experiment.

2.2. Plant Sampling and Measurement

The following characteristics were determined before and after the harvest of chamomile:

-

The height of chamomile plants, the number of branches and inflorescences on the stem, and the weight of aboveground plants were determined 3–5 days before the herb harvest. Measurements were made based on 30 plants randomly selected from each plot. Biometric features of chamomile plants were determined (picked) randomly in such a way that they were represented by plants from most single rows in each plot (both from the middle and peripheral rows). The same was done for the row spacing of 40 cm and 30 cm;

-

The herbage, including inflorescences used for the production of crushed flowers, was harvested after about 10 days from the beginning of flowering (half developed flower heads—in the second/third 10-day period of August). The harvested herbage was dried at 35 °C in an air circulation drying oven, and subsequently, it was threshed and separated from dried crushed flowers. The crushed herbal material (flowers) obtained was weighed and divided into particular fractions using sieves with the following mesh sizes: 3.0. 1.0. 0.8, and 0.4 mm;

-

The fractions obtained, i.e., disk florets, ray florets, and seeds, were weighed, whereas the other plant parts, e.g., receptacles, ground stems, and leaves, were rejected;

-

Dry matter content in the chamomile raw material was determined using the oven-dry method at 105 °C according to the standard [PN-90/A-75101/03];

-

The content of essential oil (the method of steam distillation using the Deryng apparatus) was determined based on an average sample consisting of flower heads from three successive harvests. The essential oil was isolated from the dried raw material by the distillation method described in [23] using 20 g of crushed plant material, a 1000 mL round-bottomed flask, and 400 mL of water as distillation liquid. Xylene (0.5 mL in a graduated tube) was added to take up the essential oil. The distillation time was 2 h at a rate of 2–4 mL/min;

-

Chlorophyll-a and b content was determined by liquid chromatography [24].

2.3. Statistical Analyses

The Statistica PL 13.3 program was used for the analysis of variance (ANOVA), and the Tukey’s test was used to determine the Honestly Significant Difference (HSD) value at p < 0.05. Due to the statistical insignificance of the determined results in the years of the study, the tables show the average results for 3 years.

Table 2. Chamomile plant height (cm), number of chamomile branches (pcs), and number of inflorescences per chamomile plant (pcs).

Treatment	Chamomile Plant Height	Number of Chamomile Branches	Number of Inflorescences per Chamomile Plant
Foliar sprays
A *	56.63 bc **	12.1 c	15.1 c
B	59.22 a	13.1 ab	17.0 a
C	57.22 b	12.3 ab	16.4 ab
D	57.50 bc	12.1 c	15.6 c
E	59.92 a	13.3 a	17.8 a
F	58.29 ab	13.3 a	17.0 a
G	57.97 bc	12.6 ab	16.2 ab
HSD(0.05)	1.59	1.17	1.39
Row spacing
40 cm	59.34 a	13.8 a	18.2 a
30 cm	56.87 b	11.5 b	14.7 b
HSD(0.05)	2.04	1.03	1.20
Chamomile cultivar
‘Złoty Łan’	57.91 b	14.0 a	18.2 a
‘Mastar’	58.31 a	11.4 b	14.7 b
HSD(0.05)	n.s. ***	1.03	1.20
Interaction HSD(0.05) row spacing × cultivar	1.85	n.s.	2.25
Interaction HSD(0.05) row spacing × foliar spray	n.s.	n.s.	5.06

A *—No foliar sprays application (control treatment); B—Foliar spray Herbagreen Basic; C—Foliar spray Bio-algeen S90; D—Foliar spray Effective Microorganisms—EM Farming; E—Double application of the foliar spray Herbagreen Basic; F—Double application of the foliar spray Bio-algeen S90; G—Double application of the foliar spray Effective Microorganisms—EM Farming; ** means within a column followed by different letters (a–c) are significantly different; *** not significant differences.

,

Table 3. Air-dry weight of flower heads per chamomile plant (g) and total yield of chamomile raw material (t ha⁻¹).

Treatment	Air-Dry Weight of Flower Heads	Total Yield of Chamomile
Foliar sprays
A *	0.51 c	0.82 c **
B	0.61 a	0.91 a
C	0.55 ab	0.89 ab
D	0.51 c	0.83 ab
E	0.62 a	0.92 a
F	0.57 ab	0.89 ab
G	0.54 ab	0.87 ab
HSD(0.05)	0.087	0.089
Row spacing
40 cm	0.60 a	0.96 a
30 cm	0.52 b	0.79 b
HSD(0.05)	0.05	0.088
Chamomile cultivar
‘Złoty Łan’	0.58 a	0.94 a
‘Mastar’	0.54 a	0.80 b
HSD(0.05)	n.s.	0.079

A *—No foliar sprays application (control treatment); B—Foliar spray Herbagreen Basic; C—Foliar spray Bio-algeen S90; D—Foliar spray Effective Microorganisms—EM Farming; E—Double application of the foliar spray Herbagreen Basic; F—Double application of the foliar spray Bio-algeen S90; G—Double application of the foliar spray Effective Microorganisms—EM Farming; ** means within a column followed by different letters (a–c) are significantly different.

,

Table 4. Percentage weight of disk florets, ray florets, and seeds in the total yield of chamomile raw material (in %).

Treatment	Disk Florets	Ray Florets	Seeds
A *	83.2 b **	10.5 a	6.3 a
B	89.4 a	6.1 c	4.5 b
C	84.5 b	8.7 b	6.8 a
D	83.3 b	10.2 a	6.5 a
E	89.9 a	5.8 c	4.3 b
F	85.4 b	8.2 b	6.4 a
G	83.7 b	10.0 a	6.3 a
HSD(0.05)	5.69	2.21	0.93
40 cm	88.9 a	7.3 b	3.8 b
30 cm	82.7 b	12.1 a	5.2 a
HSD(0.05)	5.89	2.09	0.88
‘Złoty Łan’	89.7 a	6.7 b	3.6 b
‘Mastar’	83.9 b	10.4 a	5.7 a
HSD(0.05)	5.69	2.10	0.89

A *—No foliar sprays application (control treatment); B—Foliar spray Herbagreen Basic; C—Foliar spray Bio-algeen S90; D—Foliar spray Effective Microorganisms—EM Farming; E—Double application of the foliar spray Herbagreen Basic; F—Double application of the foliar spray Bio-algeen S90; G—Double application of the foliar spray Effective Microorganisms—EM Farming; ** means within a column followed by different letters (a–c) are significantly different.

,

Table 5. Essential oil content in chamomile disk florets (% DM).

Treatment	Foliar Sprays	Row Spacing 40 cm	Row Spacing 30 cm	‘Złoty Łan’ Cultivar	‘Mastar’ Cultivar	‘Złoty Łan’ × Row Spacing 40 cm
A *	0.43 d	0.43	0.43	0.53	0.33	0.53
B	0.51 a **	0.50	0.53	0.69	0.33	0.67
C	0.53 a	0.43	0.62	0.72	0.34	0.57
D	0.53 a	0.48	0.58	0.48	0.58	0.48
E	0.46 c	0.43	0.48	0.45	0.46	0.38
F	0.49 ab	0.58	0.41	0.60	0.39	0.86
G	0.53 a	0.53	0.53	0.48	0.57	0.48
Mean	-	0.48 b	0.51 a	0.56 a	0.43 b	-
HSD(0.05) cultivars—0.08; row spacing—0.03; foliar sprays—0.03; row spacing × cultivars—0.02; foliar sprays × cultivars—0.03; foliar sprays × row spacing—0.04; row spacing × cultivars × foliar sprays—0.07.

A *—No foliar sprays application (control treatment); B—Foliar spray Herbagreen Basic; C—Foliar spray Bio-algeen S90; D—Foliar spray Effective Microorganisms—EM Farming; E—Double application of the foliar spray Herbagreen Basic; F—Double application of the foliar spray Bio-algeen S90; G—Double application of the foliar spray Effective Microorganisms—EM Farming; ** means within a column and row (for main effects) followed by different letters (a–d) are significantly different.

and

Table 6. Chlorophyll content in chamomile disk florets (mg·g⁻¹).

Treatment	Chlorophyll-a Content	Chlorophyll-b Content	Total Chlorophyll a + b Content
Foliar sprays
A *	0.099 f **	0.027 c	0.126 f
B	0.189 b	0.052 b	0.241 b
C	0.114 e	0.031 c	0.145 e
D	0.128 d	0.035 c	0.163 d
E	0.250 a	0.069 a	0.319 a
F	0.115 e	0.033 c	0.148 e
G	0.160 c	0.044 b	0.204 c
HSD(0.05)	0.008	0.010	0.013
Row spacing
40 cm	0.147 b	0.041 a	0.188 b
30 cm	0.155 a	0.042 a	0.197 a
HSD(0.05)	0.003	n.s. ***	0.005
Chamomile cultivar
‘Złoty Łan’	0.155 a	0.042 a	0.197 a
‘Mastar’	0.147 b	0.041 a	0.188 b
HSD(0.05)	0.003	n.s.	0.005
Interaction HSD(0.05) foliar spray × cultivar	0.013	0.016	0.021

A *—No foliar sprays application (control treatment); B—Foliar spray Herbagreen Basic; C—Foliar spray Bio-algeen S90; D—Foliar spray Effective Microorganisms—EM Farming; E—Double application of the foliar spray Herbagreen Basic; F—Double application of the foliar spray Bio-algeen S90; G—Double application of the foliar spray Effective Microorganisms—EM Farming; ** means within a column followed by different letters (a–f) are significantly different; *** not significant differences.

show the results of the studies for the main factors of the experiment (foliar sprays, row spacing, and cultivar) because only a few of the outcome features presented in these tables showed significant interactions between the main factors or no interactions at all (the detailed results are presented in the Supplementary Materials—Tables S1–S9).

3. Results

Among foliar sprays used in the experiment, regardless of the row spacing and cultivar, Herbagreen Basic applied twice (treatment E) and once (treatment B) had the most beneficial effect on chamomile plant height (significantly higher plants by 3.29–2.59 cm than control treatment A), followed Bio-algeen applied twice (treatment F)—Table 2 and Table S1. Regardless of the other factors, the wider row spacing (40 cm) contributed to significantly higher (on average by 2.47 cm; about 5%) chamomile plants than the spacing of 30 cm.

Irrespective of foliar sprays, under 40 cm row spacing conditions ‘Złoty Łan’ chamomile plants were observed to be significantly higher (on average by 3.07 cm) compared to the plant height found for row spacing of 30 cm (Table S1). On average, for chamomile cultivars (regardless of the row spacing and biopreparations), differences were statistically insignificant (a trend for higher ‘Złoty Łan’ plants was only noted)—Table 2.

Regardless of the experimental factors, a significantly higher number of branches per ‘Złoty Łan’ chamomile plant was found (on average by 19%) than in the case of cv. ‘Mastar’ (Table 2 and Table S2). A trend was observed (significant) for the highest number of branches per chamomile plant (an increase of about 11–12% in relation to objects A and D) as affected by the foliar spray Herbagreen Basic, followed by Bio-algeen, applied twice. The different row spacings, on the other hand, showed a statistically proven effect on the number of branches per chamomile plant. The wider row spacing (40 cm) promoted an about 17% higher number of branches per plant compared to the row spacing of 30 cm.

The number of inflorescences per chamomile plant was strongly related to the cultivar factor (Table 2 and Table S3). Cultivar ‘Złoty Łan’ was characterized by a significantly higher (on average by 22%) number of inflorescences per plant relative to cv. ‘Mastar’. The foliar sprays (treatment B, E, and F) did have a statistically proven effect on this trait (increasing the number of inflorescences by approximately 8–9% compared to treatments A and D). In turn, the effect of the wider row spacing (40 cm) proved to be significantly more beneficial for the number of inflorescences per chamomile plant than the spacing of 30 cm (the difference in the number of inflorescences was nearly 20%). A particularly beneficial effect of the wider row spacing on the number of inflorescences per plant chamomile was found in the case of cv. ‘Złoty Łan’ (on average 19.6 inflorescences). The interaction of the wider row spacing and application of the foliar sprays Herbagreen basic and Bio-algeen (especially double application—19.1–20.4 inflorescences) was found to influence the characteristic in question favorably (Table S3).

The air-dry weight of flower heads per chamomile plant proved to be a trait that was significantly dependent on the row spacing (Table 3 and Table S4). Growing chamomile at the wider row spacing of 40 cm contributed to a higher weight of flower heads per plant, on average by about 13%, in comparison with the flower head weight in the case of the narrower row spacing (30 cm). Herbagreen Basic (treatment B and E) significantly increased the air-dry weight of flower heads by 16% compared to treatments A and D. The effect of the cultivar factor on the trait in question was statistically insignificant.

The biometric characteristics of chamomile shown in the above tables had an influence on the total yield of chamomile raw material expressed in tonnes per ha, but the most visible relationship related to flower head weight per plant (Table 2 and Table 3).

The effect of foliar sprays on increasing the total yield of chamomile was less pronounced, but this herbal plant produced significantly higher yields (by 10–11%) in treatments E and B (Herbagreen Basic applied twice or once) in comparison with control treatment A. It was shown that there was an even stronger correlation between chamomile yield and the row spacing used in the experiment. The use of the spacing of 40 cm to grow chamomile resulted in a higher yield by 0.17 t ha⁻¹ (about 18%) relative to the narrower spacing (30 cm). The total yield of chamomile was significantly linked to the cultivar factor. Irrespective of other factors, the cultivar ‘Złoty Łan’ was found to produce higher yields by about 0.14 t ha⁻¹ (15%) than cv. ‘Mastar’ (Table 3 and Table S5).

Disk florets by far dominated in total yield of crushed chamomile raw material, accounting for 83.2–89.9% of the herbal raw material (Table 4). Ray florets (about 5.8–12.1%) and seeds (about 3.6–6.8%) had a lower percentage. Among the foliar sprays used, Herbagreen Basic applied twice and once (treatments E and B) significantly contributed to a higher percentage of disk florets in the yield (at the same time to a significantly lower percentage of ray florets) in comparison with control treatment A and the treatments with an application of Effective Microorganisms (D and G). The foliar spray Herbagreen Basic also had a significant effect on the lowest percentage of seeds in the total chamomile yield. A significantly higher percentage of disk florets, as well as a lower percentage of ray florets and seeds, were found in the treatments where chamomile was grown at the row spacing of 40 cm compared to the spacing of 30 cm. When comparing the total yield structure of both chamomile cultivars, the percentage of disk florets was found to be significantly higher, but at the same time, a significantly lower percentage of ray florets and seeds in cv. ‘Złoty Łan’ inflorescences was determined compared to cv. ‘Mastar’.

The dried herbal material of chamomile (disk florets) prepared for chemical analysis was uniform in terms of dry matter content—the individual experimental treatments did not modify this trait significantly since the dry matter content was about 94.5–95.0%; hence, the water content in the herbal material was 5.0–5.5%.

Essential oils are the main component in the dry matter of chamomile raw material (Table 5 and Table S6).

The content of essential oil in chamomile disk florets was found to be significantly dependent on all experimental factors (Table 5). Application of the foliar sprays resulted in significantly higher essential oil content in the chamomile raw material compared to the control treatment (A), irrespective of the number of applications, whereas application of EM-Farming (treatments D and G) and Bio-algeen (treatment C) produced the most beneficial effect on essential oil content since the oil content was found to increase by 0.10 percentage point (p.p.) Chamomile grown at the wider (40 cm) row spacing had a lower content of essential oil by about 0.03 p.p. relative to the spacing of 30 cm, regardless of the cultivar and foliar spray. In the cultivar ‘Złoty Łan’, its content was higher by 0.13 (p.p.) in comparison with cv. ‘Mastar’. The interaction between essential oil content and the row spacing of 40 cm was found to be significantly negative for cv. ‘Mastar’. Furthermore, the correlation between the cultivar factor and row spacing, as well as between row spacing and foliar sprays, was observed to be significant with regard to essential oil content. The highest essential oil content (0.86% DM) was recorded in the wide-row (40 cm) cultivation of cv. ‘Złoty Łan’ fertilized twice with Bio-algeen (Table 5).

The foliar sprays used in this experiment (applied both twice and once) caused a significant increase in chlorophyll-a content in comparison with the control treatment. Significantly the greatest effect on chlorophyll-a content was exhibited by Herbagreen Basic applied twice (0.250 mg·g⁻¹) and applied once (0.189 mg·g⁻¹), as well as by Effective Microorganisms applied twice (0.160 mg·g⁻¹). The other treatments of chamomile foliar fertilization influenced chlorophyll-a content in the range of 0.114–0.128 mg·g⁻¹. A statistically proven higher chlorophyll-a content in the chamomile raw material (by 5.2%) was promoted by growing this herbal plant at the narrower row spacing (30 cm). The herbal raw material of the chamomile cultivar ‘Złoty Łan’ was characterized by a significantly higher chlorophyll content (by about 5%) relative to cv. ‘Mastar’ (Table 6). A significantly higher chlorophyll-a content in the chamomile raw material was observed as a result of the following interactions: Herbagreen Basic applied twice × cv. ‘Złoty Łan’ (0.266 mg·g⁻¹) and Herbagreen Basic applied twice × cv. ‘Mastar’ (0.233 mg·g⁻¹), but also for the following interaction: single spraying with Herbagreen Basic × cv. ‘Złoty Łan’ (0.203 mg·g⁻¹) (Table S7).

The chlorophyll-b content in chamomile raw material showed significant relationships only under the influence of foliar sprays and for interaction cultivar × foliar spray (Table 6 and Table S8). Significantly, the highest chlorophyll-b content was observed for double application of Herbagreen Basic (0.069 mg·g⁻¹) and in the case of a single application of Herbagreen Basic (0.052 mg·g⁻¹). Significantly, the largest amount of chlorophyll-b in the chamomile raw material was found for the interaction cv. ‘Złoty Łan’ × Herbagreen Basic applied twice (0.072 mg·g⁻¹). The chlorophyll-b content was almost identical in both chamomile cultivars in question, regardless of other experimental factors.

Total chlorophyll a + b content in chamomile disk florets was significantly dependent on all experimental factors (Table 6 and Table S9). Application of the foliar sprays increased total chlorophylls a + b in comparison to the control treatment (without application of the foliar sprays). As far as the individual treatments with foliar spray application were concerned, significant differences were found which were associated with the effect on total chlorophyll content. Double application (0.319 mg·g⁻¹) and a single application of the foliar spray Herbagreen Basic (0.240 mg·g⁻¹), as well as double spraying with Effective Microorganisms (0.204 mg·g⁻¹), had the most beneficial effect on total chlorophylls a + b. Irrespective of the other experimental factors, growing chamomile at the row spacing of 40 cm contributed to a decrease in total chlorophylls, on average by 5%, compared to the row spacing of 30 cm. Regardless of foliar sprays and row spacing, herbal raw material obtained from cv. ‘Złoty Łan’ was characterized by a significantly higher (by about 7%) total chlorophyll a + b content in comparison with cv. ‘Mastar’. Significantly, the highest total chlorophyll a + b content (0.339 mg·g⁻¹) was found for cv. ‘Zloty Łan’ in the case of double application of Herbagreen Basic.

4. Discussion

4.1. Influence of the Varietal Factor on the Productivity and Quality of Chamomile Raw Material

In the present study, the chamomile cultivar ‘Złoty Łan’ was characterized by a statistically significantly higher yield, more favorable biometric parameters, and also better quality characteristics than ‘Mastar’. ‘Złoty Łan’ is a cultivar with an established reputation in the herbal market in Poland, well adapted to the agri-climatic conditions prevailing in Poland. The cultivar ‘Mastar’ is relatively less popular in agricultural practice, and it was selected for this study due to its potentially high essential oil content, which is similar to that of ‘Złoty Łan’. The results obtained in this study and the results of other authors’ research demonstrate that selection of an appropriate cultivar is an important factor affecting the yield and quality of herbal plants. Selecting native cultivars well adapted to local soil and climatic conditions gives the best results [10,15,21,25,26]. This thesis is confirmed by the results of a study by Kwiatkowski and Harasim [22] on garden thyme. In the above-mentioned study, the Polish cultivar ‘Słoneczko’ showed a statistically significantly higher yield and better quality parameters for all the characteristics determined than the Romanian cultivar ‘De Dolj’. Shalaby et al. [27], Singh et al. [2], and Panaitescu et al. [28] also claim that varieties of herbal plants are characterized by high yield potential and high quality of herbal raw material if they are grown in the country of origin or in a climatically similar region.

4.2. Influence of Biopreparations on the Productivity and Quality of Chamomile Raw Material

The results of the present study reveal that the biopreparations used had an influence on chamomile yield quantity (especially the foliar fertilizer Herbagreen Basic, while Bio-algeen S90 to a lesser extent). On the other hand, the essential oil and chlorophyll content in the chamomile raw material increased significantly under the influence of both Herbagreen Basic and Effective Microorganisms. The growth stimulator Bio-algeen S90 did not have a statistically confirmed effect on the quality characteristics of chamomile.

The results of other authors’ research [29,30] show that ensuring optimal growth and development of crop plants by supplying them with a sufficient amount of nutrients through foliar application allows higher yields to be obtained. As a result of foliar fertilization of plants, there is increased nitrogen uptake efficiency, decreased chlorophyll degradation and leaf senescence, and thereby a higher leaf greenness index [31,32,33,34]. Biopreparations also contribute to an increase in the above-ground dry weight of plants [35,36], which is evidenced in the present study. It should be clearly emphasized that the effect of biopreparations does not consist in providing plants with nutrients but in stimulating various development mechanisms in the plant and creating their resistance to unfavorable factors of the soil environment (pathogens) [37,38,39]. The mechanism of such action of biopreparations results from the fact that the nutritional status of foliar-treated plants improves as a result of modification of root system architecture (length, density, and number of lateral roots). In turn, a consequence of this is greater nutrient use efficiency, which thus increases fresh and dry biomass [32,40] and also chlorophyll content [41,42,43,44].

In this research, Effective Microorganisms had a smaller effect than the sprays Herbagreen Basic and Bio-algeen on the chamomile yield structure and quantity. Nonetheless, they distinctly influenced the quality characteristics of chamomile. Radkowski and Radkowska [45], on the other hand, found EM to have a significant effect on the increase in plant biomass. Moreover, similarly to the present study, these authors found EM (particularly when applied twice) to have a significant influence on the accumulation of nutrients in plant raw material (especially the following macronutrients: Cu, Zn, Mn, and Fe). Shah et al. [46] argue for positive effects of microbiological preparations on the condition of plants and soil, which is manifested in improved yield quantity and quality. Positive effects of EM in a spring wheat crop were reported by Piskier [47] and Kołodziejczyk et al. [48]. Based on their own study, Meyer et al. [49] conclude that Effective Microorganisms did not improve yields and soil quality during their 4-year-long application in a field experiment under the moderate climatic conditions of Central Europe. Other studies [50,51] confirmed the lack of effect of Effective Microorganisms on crop productivity.

Using the biostimulators Asahi SL and Bio-algeen S90 as well as the micronutrient fertilizer Ekolist P in chamomile cultivation, Woropaj-Janczak et al. [52] proved that only the application of Asahi SL contributed to an increase in dry matter yield of the chamomile herb. In turn, Kwiatkowski [10] and Fageria et al. [53] confirm the favorable results of the application of compound fertilizers.

The positive effects of growth biostimulators (Asahi SL, Bio-algeen, and Tytanit) on herbal plants were also proven by Kwiatkowski and Juszczak [14] and Kwiatkowski [54] on the example of garden thyme and sweet basil. The above-mentioned growth biostimulators (especially Asahi SL) also contribute to an increase in yield and improvement in quality parameters of carrot roots [55,56]. In the present study, Herbagreen Basic was found to be particularly suitable for growing chamomile. The effects of foliar fertilization of soybean and different herbal and aromatic plants observed by Veneziano et al. [57] and Shahrajabian et al. [58] included a significant increase in yield, greater resistance to insects, pests, and diseases, better drought tolerance, and higher yield quality. The results of the research by Jankowski et al. [59] on the example of winter oilseed rape and the results of the research by Szewczuk and Juszczak [60] on the example of bean confirm the positive effect of biopreparations on the condition of plants, and consequently on their yield and quality of the raw material.

This study demonstrates that foliar-applied biopreparations modified the chemical composition of chamomile. Nonetheless, the degree of their influence was not as strong as on raw material yield and biometric characteristics of chamomile. Some authors [61,62,63,64,65,66,67] are of the opinion that the scale of improvement in the chemical composition of plant raw material as affected by biopreparations results from modulation of plant physiology (root morphology, H+-ATPase activity), increased nutrient uptake, and translocation of micro- and macronutrients.

4.3. Influence of Row Spacing on the Productivity and Quality of Chamomile Raw Material

This study reveals that from the point of view of biometric characteristics and yield quantity of chamomile, wider row spacing (40 cm) was more favorable. The narrower row spacing (30 cm), in turn, had a more beneficial effect on the quality of chamomile raw material. In the example of marigold cultivation, Shakib et al. [68] claim that row spacing (the number of plants in a plot) did not have a significant influence on the chemical composition of herbal raw material. Saglam et al. [69], in turn, prove on the example of lemon balm cultivation that, by changing the spacing from 50 × 30 cm to 40 × 20 cm, a denser row spacing contributes to a significantly higher yield of herbal raw material. On the other hand, a decrease in row spacing has a smaller effect on the quality characteristics of herbal raw material. In the example of golden melon, Ayeni et al. [70] prove that the knowledge of the best plant density obtained through row spacing may affect yield potential. These authors found an increase in golden melon yield with increasing row spacing.

Research conducted by Kwiatkowski [10] demonstrated that the cultivation of chamomile at a row spacing of 45 cm or 35 cm rows had the most beneficial effect on the yield and quality of chamomile raw material. A narrow row spacing (25 cm) resulted in reduced yields and deteriorated quality. In a study by Salomon [71], row spacing was not found to affect the quality parameters of chamomile significantly. On the other hand, research carried out on a pot marigold plantation reveals that extreme values (the lowest one was 30 plants per 1 m², while the highest one was 90 plants per 1 m²) of plant density contribute to decreased yields and quality of pot marigold raw material compared to a density of 50–70 plants per 1 m² [72]. Similar observations were also made in a study by Shakib et al. [68].

A study conducted by Kwiatkowski and Harasim [22] demonstrates that the wider row spacing (40 cm) contributed to higher yields of thyme. When the narrower inter-rows (30 cm) were used to grow this herbal plant, in turn, some more favorable quality parameters were attained (essential oil content and polyphenol content).

5. Conclusions

In regard to the biopreparations tested in the experiment, Herbagreen Basic proved to be the most beneficial, especially when applied twice. This biopreparation had the most favorable effect on the biometric characteristics and yield of chamomile, but also on the quality of herbal raw material. Bio-algeen S90 had a significantly beneficial effect on biometric characteristics and chamomile yield, while Effective Microorganisms (EM Farming) had a positive effect on the content of essential oils and chlorophyll.

The wider spacing of 40 cm proved to be more favorable from the point of view of plant biometrics as well as total yield quantity and yield structure. The narrower row spacing (30 cm) significantly positively influenced most of the chemical composition indices of chamomile raw material.

The ‘Złoty Łan’ cultivar was characterized by more favorable biometric characteristics and a higher total yield of herbal raw material and had a more favorable chemical composition of the herbal raw material compared to the ‘Mastar’ cultivar.

A significant interaction was found in the content of essential oil in the case of ‘Złoty Łan’ cultivar sown at a row spacing of 30 cm with the use of Herbagreen Basic biopreparation twice.