Effect of Crop Protection Intensity and Nitrogen Fertilisation on the Quality Parameters of Spelt Wheat Grain cv. ‘Rokosz’ Grown in South-Eastern Poland

Abstract

Spelt wheat is one of the oldest wheats cultivated by humans. It is characterised by high nutritional values and is sought after by consumers. Additionally, it does not have high habitat and fertilisation requirements and is resistant to diseases. The aim of this study was to determine the effect of different levels of nitrogen fertilisation and the intensification of fungicide protection on the grain quality characteristics of spelt cv. ‘Rokosz’ grown under south-eastern Polish conditions. The present research showed that the intensification of fungicide crop protection and increasing the nitrogen dose from 70 to 130 kg ha⁻¹ had a positive effect on the quality features of spelt grains. The highest protein, gluten and starch contents were found after four fungicide treatments. These parameters increased their values under the influence of fungicides. After the application of 130 kg ha⁻¹, spelt wheat grain had the most favourable chemical composition, containing the most protein, gluten, soluble dietary fibre, insoluble dietary fibre and fat. It also had a positive effect on the Zeleny sedimentation index and the amino acid content of the grain. Due to the favourable response of the spelt cv. ‘Rokosz’ to intensified fungicide protection and nitrogen fertilisation, it should be recommended for cultivation in integrated technology.

1. Introduction

Spelt wheat (Triticum aestivum ssp. spelta L.), until recently a forgotten subspecies of common wheat (Triticum aestivum ssp. vulgare L.), is now gaining popularity among healthy food producers and organic farmers [1,2]. The area under cultivation of this crop is increasing year by year, as there is growing interest in biodiversity conservation and organic farming, where spelt wheat excels [3,4,5,6]. Spelt wheat is emerging as an alternative cereal that fills a missing need in the nutrition market [7]. Increased interest in spelt wheat has been reported due to its health benefits, high nutritional value and its suitability in breeding programmes in regard to developing varieties with excellent grain quality and pathogen resistance [8]. The composition of the spelt grain, like other wheat species, is determined by both genetic and environmental factors. Spelt wheat is genetically diverse, with modern varieties, old land varieties and new breeding lines. Due to this fact, spelt wheat of the old varieties differs from its new breeding lines in terms of protein content, quality, starch content and dietary fibre [8,9], while the technological quality of grain and flour in hybrid varieties does not differ from the quality of traditional varieties [10]. The qualitative and molecular analysis of 28 European spelt varieties by Gulyas et al. [11] showed a high level of genetic diversity in spelt wheat, finding two distinct groups: varieties containing bread wheat genetic material and true spelt, which does not contain bread wheat genetic material. According to Okoń et al. [12], old German spelt varieties such as Franckenkorn, Badengold, Schwabenkorn, Schwabenspelz, Ceralio, Ostro, and Oberkulmer Rotkorn are characterised by low levels of genetic diversity.

At present, 106 varieties of spelt are registered in 16 European countries in the Common Catalogue of Varieties of Agricultural Plant Species (CCA). Seven of them are Polish varieties—five winter varieties (Rokosz, SM Amalte, SM Fides, SM Orkus and Speldorado) and two spring varieties (Kuiavia and Wirtas) [13]. ‘Rokosz’ is a cultivar that was entered into the national register in 2012 and has certain characteristics of common wheat. ‘Rokosz’ has a high yield potential and it is characterised by a small share of chaff in the yield [14]. Compared to the old Schwabenspelz variety, it is more susceptible to weed infestation, less tolerant to extensive cultivation and more susceptible to infection by pathogenic fungi, which is why it contains more mucotoxins in the grain [2], while no reduction in the grain and flour quality was observed under pro-ecological cultivation conditions [15].

Consumers looking for foods with high dietary value are keen to choose spelt wheat products based on its nutrient richness and health-promoting properties [6,16,17]. Spelt wheat is widely used in the production of flour, pasta, bakery products, coffee and beverages [18,19]. The cv. ‘Rokosz’, according to a study by Podolska et al. [16]., is well suited for waffle production. Despite its high affinity with common wheat, spelt wheat stands out both in terms of morphology and soil and agrotechnical requirements. Spelt wheat is definitely more resistant to unfavourable environmental factors and easily adapts to extensive cultivation [6,8]. Spelt wheat is an ancient wheat species characterised by grains covered with husks [8,20,21]. The husks covering the spelt wheat grain protect it from all contaminants and the negative effects of plant protection products [22]. However, Mankevičienė et al. [21] showed that there was a higher concentration of mycotoxins in grains with husk than in grains without husk.

Spelt wheat grain contains up to 17% total protein, characterised by a favourable amino acid composition [22,23,24]. This is due to the high proportion of the aleurone layer in the kernel mass. This protein is characterised by a higher digestibility and biological quality than in common wheat [22,25]. Spelt wheat is a rich source of fibre, silicic acid, B vitamins (B1, B2, B6, PP) and fat-soluble vitamins, i.e., A, E, D, which distinguishes spelt wheat from other cereals [22,25,26]. The fat content of wheat grains ranges from 1% to 5%, making spelt wheat a richer source of this component than common wheat. Among the fatty acids, linoleic acid dominates, accounting for more than 55%, followed by oleic acid and palmitic acid. An important aspect in assessing the nutritional value of spelt wheat is the level of minerals [6,25,27,28]. Particular attention is paid to the high content of copper, zinc, phosphorus, selenium, as well as iron and manganese [6,12,29,30,31]. Research by Kraska et al. [32] shows that spelt wheat grain has a higher abundance of macro- and micronutrients at milk maturity than at full maturity. Spelt wheat also has a high antioxidant potential [4,31]; additionally, spelt wheat flour has a significantly higher concentration of phenolic compounds compared to bread wheat flour [30].

The growing awareness of consumers leads them to seek products based on natural ingredients that promote a healthy lifestyle [6,29,33]. These products should be of very good quality and made from raw materials with the highest possible technological and quality parameters. The nutritional qualities of agricultural crops depend not only on genetic factors but also on the way they are produced. Some of the main factors influencing the consumption value include chemical canopy protection and mineral fertilisation [34]. Therefore, a study was conducted to evaluate different levels of nitrogen fertilisation and the intensification of fungicide protection on the grain quality characteristics of spelt wheat cv. ‘Rokosz’ grown under south-eastern Polish conditions.

2. Materials and Methods

2.1. Location of the Experiment and Soil and Climatic Conditions

Field research was carried out in 2018–2021 at the Experimental Farm in Czesławice (51°18′23″ N, 22°16′2″ E) belonging to the University of Life Sciences in Lublin, Poland.

The experiment was established on a loess-derived Luvisol. The arable layer of the soil was characterised by a high availability of phosphorus (P—78.5–79.6 mg kg⁻¹ soil) and potassium (K—120.3–131.8 mg kg⁻¹ soil), a medium availability of magnesium (Mg—81–86 mg kg⁻¹ soil), a slightly acidic pH (in 1 M KCl—6.2–6.4) and a humus content of 1.61–1.64%.

The 2019/2020 and 2020/2021 seasons could be described as wet, with the total precipitation exceeding the 1963–2010 LTA by 115.6 mm and 216.9 mm, respectively (

Table 1. Total precipitations and mean monthly air temperature in the growing season of winter spelt, recorded by the Meteorological Station in Czesławice (Poland). LTA—long-term average.

Years	Months												Sum/ Mean
	IX	X	XI	XII	I	II	III	IV	V	VI	VII	VIII
Rainfalls (mm)
2018/ 2019	54.7	41.3	15.2	70.8	31.5	14.6	27.1	39.0	87.0	11.2	46.3	52.0	490.7
2019/ 2020	33.5	37.0	56.3	46.3	14.1	76.5	26.0	19.0	111.4	170.3	67.8	59.3	717.5
2020/ 2021	128.5	93.4	17.4	16.0	31.7	42.1	14.9	58.3	68.0	68.3	82.4	197.8	818.8
LTA 1963–2010	59.5	45.6	41.0	36.9	30.3	29.2	31.3	42.4	63.5	72.7	80.0	69.5	601.9
Temperature (°C)
2018/ 2019	14.7	9.2	3.9	−0.2	−3.4	2.5	5.5	10.3	14.4	22.9	20.0	21.9	10.2
2019/ 2020	16.3	12.6	6.6	2.6	1.2	3.2	4.6	8.6	11.2	17.4	18.8	20.4	10.3
2020/ 2021	15.7	10.9	5.2	1.9	0.1	−2.2	2.6	6.4	11.6	18.6	22.0	17.2	9.2
LTA 1963–2010	13.1	7.9	2.9	−1.3	−3.0	−1.7	1.8	7.7	13.6	16.5	18.3	17.7	7.8

). The 2018/2019 season was very dry, with the rainfall being 111.2 mm below the long-term average (LTA). Throughout the months of May, June and September in 2020 and the month of August in 2021, the precipitation was well above the long-term average (LTA). The periods of 2019—June, 2020—April and 2021—March can be described as being very dry. Temperature ranges were similar in all the growing seasons. The mean temperature in these years was 2.4, 2.5 and 1.4 °C higher than in the period 1963–2010 (LTA).

2.2. Experimental Design and Agronomic Practises

The experiment was replicated in triplicate using the split-block design. The area of each plot was 18 m². The winter form of spelt wheat, cultivar ‘Rokosz’, was tested. The seed rate was 130 kg ha⁻¹. The research factors were differentiated crop protection against fungal diseases and nitrogen fertilisation.

The crop protection treatments included the following combinations:

A—control plot (without fungicide protection);

B—two fungicide treatments—Yamato 303 SE (thiophanate-methyl + tetraconazole) at BBCH—30–31 at a rate of 1.5 L ha⁻¹ and Optan 183 SE (pyraclostrobin + epoxiconazole) at BBCH—30–59 at a rate of 1.5 L ha⁻¹;

C—three fungicide treatments—Yamato 303 SE (thiophanate-methyl + tetraconazole) at stage BBCH—30–31 at a dose of 1.5 L ha⁻¹, Optan 183 SE (pyraclostrobin + epoxiconazole) at stage BBCH—30–59 at a dose of 1.5 L ha⁻¹ and Virtuoz 520 EC (prochloraz + tebuconazole + proquinazid) at stage BBCH—20–59 at a dose of 1.0 L ha⁻¹;

D—four fungicide treatments—Yamato 303 SE (thiophanate-methyl + tetraconazole) at stage BBCH—30–31 at a dose of 1.5 L ha⁻¹, Optan 183 SE (pyraclostrobin + epoxiconazole) at stage BBCH—30–59 at a dose of 1, 5 L ha⁻¹, Virtuoz 520 EC (prochloraz + tebuconazole + proquinazid) at stage BBCH—20–59 at a dose of 1 L ha⁻¹ and Tilt Turbo 575 EC (propiconazole + fenpropidin) at stage BBCH—30–59 at a dose of 0.9 L ha⁻¹.

The second research factor was the different rates of nitrogen fertilisation:

N₀—no nitrogen fertilisation (control);

N₁—70 kg ha⁻¹;

N₂—100 kg ha⁻¹;

N₃—130 kg ha⁻¹.

Nitrogen was applied in the form of ammonium nitrate (34%). Ammonium nitrate was applied in three divided doses—60% of the dose in early spring, immediately after the start of vegetation (BBCH—14–16), 20% at the stem shoot stage (BBCH—21–23) and 20% before earing (BBCH—37–39).

Phosphorus and potassium fertilisation was applied in autumn before sowing the winter spelt wheat at a rate of P—27 kg ha⁻¹ and K—51 kg ha⁻¹. The forecrop of spelt wheat was winter wheat. The tillage was typical of common wheat cultivation. After harvesting the forecrop (winter wheat), ploughing and sowing was carried out, and the soil was seasoned for sowing with a cultivating unit. Wheat was sown in the third decade of September with a field drill.

At the BBCH—21–29 wheat stage, a herbicide treatment was carried out with Chisel 75 WG (thifensulfuron-methyl + chlorosulfuron) at a dose of 60 g ha⁻¹ with the adjuvant Trend 90 EC (ethoxylated isodecyl alcohol) at a concentration of 0.1%. Wheat was protected against pests with Decis Mega 50 EW (deltamethrin) at a dose of 0.2 L ha⁻¹.

2.3. Chemical Analyses of Grain

Selected technological and quality parameters of spelt wheat grain were determined in samples taken from each plot. The content of total protein, gluten and starch in the grain, as well as the Zeleny sedimentation index and moisture content, were determined using the Omeg Analizer G whole grain computer transmission analyser (Bruins Instruments, Germany, Puchheim). This is a near-infrared spectrometer which is used to analyse the composition of samples using the near-infrared absorbency characteristics of the sample spectra.

The amino acid content of the grain was determined by HPLC (AAA 400, Ingos, Prague, Czech Republic). The amino acids were separated by ion exchange chromatography. A 0.37 × 45 cm column was packed with ion exchange resin (Ostion LG ANB, Tessek, Prague, Czech Republic). Amino acid identification was performed using a photometric detector at 570 nm for all amino acids and at 440 nm for proline only [35].

The total dihydroxyphenol content was expressed as a caffeic acid equivalent spectrophotometrically at a wavelength of λ = 725 nm (Shimadzu 1800 spectrophotometer, Shimadzu Corp., Kyoto, Japan). To make the measurement on the spectrophotometer, 50 μL—500 μL of the extract (depending on the expected value of absorption of the tested sample) was transferred into a volumetric flask. Amounts of 2.0 mL methanol, 10 mL H₂O, 2 mL Folin reagent, and 1.0 mL of a 10% solution of Na₂CO₃ were added. The samples were put aside for 0.5 h; subsequently, they were made up with deionised water up to the mark and measured on the spectrophotometer at a wavelength of λ = 725 mm in relation to the reference sample [36].

The soluble and insoluble fibre content was determined by the enzymatic gravimetric method using a Fibertec 2010 system (FOSS, Hillerød, Denmark). The sample was subjected to digestion with the following enzymes: thermostable alpha-amylase, pepsin, and pancreatin. The weight of the undigested residue was determined, and the soluble dietary fibre supernatant was precipitated from the solution before its weight was also determined. The crude fat content was determined via the Soxhlet extraction-gravimetric method.

The chemical quality tests of the grain were carried out in the Central Research Laboratory, which is part of the Quality Management System according to PN-EN ISO 9001:2001 (Accreditation Certificate No. AB 1375) [37]. The laboratory provides accredited testing services in accordance with the PN-EN ISO/IEC 17025:2005 Quality Management Standard for Testing Laboratories [38].

2.4. Physical Parameters of the Grain

Grain uniformity was determined on Vogel sieves by separating the grain sample into five fractions with grain thicknesses greater than 2.8; 2.5; 2.2; 1.8 mm and less than 1.8 mm according to BN-69/9131-02 [39].

2.5. Statistical Analysis

Results obtained from the germination experiments were analysed statistically using the analysis of variance (ANOVA). The significance of the differences was estimated by a Tukey test at a significance level of p = 0.05. ANALWAR-5.3.FR statistical software was used for calculations. Before statistical tests were conducted, data were checked for normality using the Shapiro–Wilk W test.

3. Results

The results of the study showed that weather conditions had a significant effect on the content of the protein, gluten and the sedimentation index in grain (

Table 2. Effect of meteorological conditions, crop protection, nitrogen fertilisation, and the interaction of experimental factors on examined features.

Feature	Y	CP	NF	CP × NF	Y × CP	Y × NF	Y × CP × NF
Protein	**	*	**	*	ns	*	ns
Gluten	**	*	**	*	ns	*	ns
Zeleny sedimentation index	*	*	*	*	ns	ns	ns
Starch	ns	*	*	*	ns	ns	ns
Insoluble dietary fibre	ns	ns	*	*	ns	ns	ns
Soluble dietary fibre	ns	ns	*	ns	ns	ns	ns
Fat	ns	ns	*	ns	ns	ns	ns
O-dihydroxyphenol	ns	ns	ns	ns	ns	ns	ns
Grain fraction	ns	*	*	*	ns	ns	ns

Y—years of research; CP—crop protection; NF—nitrogen fertilisation; ns—no significant difference between treatments at p ≤ 0.05; * significant difference between treatments at p ≤ 0.05; ** significant difference between treatments at p ≤ 0.01.

). There was also a significant effect regarding the interaction between the years of research and nitrogen fertilisation on protein and gluten content. This paper presents the relationships of the studied traits with the main factors, the interaction between crop protection and nitrogen fertilisation, as well as the significant relationships in the years of research.

3.1. Chemical Analyses of Grain

The content of total protein in spelt wheat grain differed significantly between the variants of crop protection and nitrogen fertilisation and in the interaction of both factors (

Table 3. Total protein content [%] in the grain of spelt wheat cv. ‘Rokosz’ depending on crop protection and nitrogen fertilisation—mean for 2019–2021.

Crop Protection	Nitrogen Fertilisation				Mean
	N0**	N1	N2	N3
A*	12.05 ± 0.23	11.59 ± 0.19	11.99 ± 0.23	12.25 ± 0.21	11.97 ± 1.63
B	11.08 ± 0.41	11.08 ± 0.31	11.06 ± 0.20	12.27 ± 0.09	11.37 ± 3.96
C	11.35 ± 0.13	11.43 ± 0.41	12.01 ± 0.23	13.54 ± 0.66	12.08 ± 2.77
D	12.11 ± 0.23	12.23 ± 0.29	11.77 ± 0.59	12.26 ± 0.22	12.09 ± 3.04
Mean	11.65 ± 0.67	11.58 ± 2.18	11.71 ± 2.38	12.58 ± 4.05	-
HSD (p ≤ 0.05)	for crop protection				0.055
	for nitrogen fertilisation				0.082
	for interaction crop protection x× nitrogen fertilisation				0.122

Explanation: A*—control object (without fungicide protection), B—two fungicide treatments, C—three fungicide treatments, D—four fungicide treatments; N₀**—no nitrogen fertilisation (control object), N₁—70 kg ha⁻¹, N₂—100 kg ha⁻¹, N₃—130 kg ha⁻¹.

). Analysing chemical protection, significant differences were found between the variant without fungicide protection and the variants with fungicide application, as well as between the site with two fungicides and the variants with three and four treatments. The highest total protein content was recorded after the fourfold fungicide treatment (12.09%). Nitrogen fertilisation had a significant effect on the total protein content of the grain. The highest content of this component, significantly higher relative to all other nitrogen fertilisation variants, was found under the conditions of the application of the highest dose of ammonium nitrate. Analysing interaction relations, it was found that, in objects A, B and C, the highest protein content, significantly higher in relation to all other fertilisation variants, was found in grain obtained from plots fertilised with a nitrogen dose of 130 kg ha⁻¹. In the object with the most intensive fungicide protection (D), also under the conditions of the highest nitrogen dose application, the grain protein content was the highest. This value was statistically equal to the object where 70 kg N ha⁻¹ was applied.

Weather conditions in each year of the experiment significantly modified the protein content in the spelt wheat grain (Figure 1). The highest content of this component in the grain was obtained in the 2018/2019 growing season, which was characterised by the lowest rainfall and high temperatures in the spring and summer months of 2019, which probably had a positive effect on protein accumulation in the grain. In the other two growing seasons, the amount of protein was at a similar level.

In the first year of the study, the increasing nitrogen fertilisation significantly increased the grain protein content (Figure 2). In 2020, after the application of 100 and 130 kg N per ha (N₂ and N₃, respectively), the protein content was significantly higher compared to the lowest nitrogen dose (N₁). In the object where nitrogen fertilisation was not applied (N₀), the amount of protein in the grain was significantly lower compared to the plots where the highest nitrogen dose was applied (N₃). In the last year of the study, the grain from the plots fertilised with the highest nitrogen dose (N₃) was characterised by a significantly higher protein content.

The experimental factors and their interactions significantly influenced the gluten content of spelt wheat grain (

Table 4. Gluten content [%] in grain of the spelt wheat cv. ‘Rokosz’ depending on crop protection and nitrogen fertilisation—mean for 2019–2021.

Crop Protection	Nitrogen Fertilisation				Mean
	N0	N1	N2	N3
A	28.70 ± 2.30	27.89 ± 1.54	27.94 ± 0.05	28.99 ± 1.13	28.38 ± 0.55
B	26.55 ± 0.10	26.32 ± 0.82	26.89 ± 1.41	29.49 ± ±0.84	27.31 ± 1.47
C	26.57 ± 0.99	26.58 ± 0.31	28.90 ± 1.48	31.85 ± 2.02	28.48 ± 2.50
D	27.32 ± 0.77	29.43 ± 0.84	26.32 ± 0.94	30.97 ± 1.85	28.51 ± 2.09
Mean	27.29 ± 1.01	27.56 ± 1.43	27.51 ± 1.14	30.33 ± 1.32
HSD (p ≤ 0.05)	for crop protection				0.186
	for nitrogen fertilisation				0.274
	for interaction crop protection × nitrogen fertilisation				0.412

Explanation: A—control object (without fungicide protection), B—two fungicide treatments, C—three fungicide treatments, D—four fungicide treatments; N₀—no nitrogen fertilisation (control object), N_1—70 kg ha⁻¹, N₂—100 kg ha⁻¹, N₃—130 kg ha⁻¹.

). Comparing the crop protection variants, the lowest gluten content was, significantly, found in the plot where two fungicide treatments were applied. The gluten content of the other protection variants did not differ significantly from each other. Only the highest dose of nitrogen fertilisation increased the content of this component in the grain.

Similar to protein (Figure 1), the highest gluten content was found in the first year of the study (2019) (Figure 3). In 2020 and 2021, the amount of this component was at a similar level. In each year of the study, the gluten content of the grain was highest in the plots where the highest nitrogen dose was applied (N3) (Figure 4).

The experiment showed the effect of nitrogen fertilisation and crop protection on the amino acid composition of spelt wheat protein (

Table 5. Amino acid content in spelt wheat grain (g·kg⁻¹)—mean for 2020–2021.

Parameter	Nitrogen Fertilisation				Crop Protection
	N0	N1	N2	N3	A	B	C	D
Asp	5.28 a	5.74 b	6.10 c	6.91 d	5.78 A	6.12 B	6.14 B	5.99 AB
Thr	2.61 a	2.82 b	3.02 c	3.27 d	2.87 A	2.96 A	2.92 A	2.97 A
Ser	4.08 a	4.46 b	4.79 c	5.30 d	4.54 A	4.58 A	4.76 A	4.75 A
Glu	30.90 a	34.28 b	37.53 c	42.65 d	35.48 A	35.63 AB	37.20 B	37.05 AB
Pro	9.40 a	11.68 b	12.23 c	14.65 d	11.53 B	10.95 A	13.31 D	12.17 C
Gly	3.86 a	4.23 b	4.46 c	4.90 d	4.25 A	4.35 B	4.43 B	4.43 B
Ala	3.39 a	3.66 b	3.86 c	4.18 d	3.66 A	3.81 A	3.79 A	3.82 A
Cys-A	3.88 b	3.30 a	3.98 b	3.23 a	3.64 B	3.90 C	3.24 A	3.62 B
Val	4.02 a	4.32 b	4.67 c	4.99 c	4.42 A	4.60 A	4.37 A	4.60 A
Sulf. met.	2.59 a	2.25 a	2.68 a	2.30 a	2.52 BC	2.64 C	2.18 A	2.49 B
Ile	2.97 a	3.28 b	3.56 c	3.90 d	3.35 A	3.43 A	3.44 A	3.49 A
Leu	6.44 a	7.00 b	7.57 c	8.27 d	7.17 A	7.37 A	7.27 A	7.46 A
Tyr	2.39 a	2.53 b	2.83 c	3.05 d	2.63 A	2.71 A	2.70 A	2.77 A
Phe	4.40 a	4.72 b	5.23 c	5.80 d	4.95 A	5.08 AB	4.99 A	5.13 B
His	2.27 a	2.51 b	2.70 c	2.93 d	2.56 A	2.62 A	2.58 A	2.66 A
Lys	2.77 a	2.93 b	3.13 c	3.32 d	2.95 A	3.15 B	2.99 AB	3.06 AB
Arg	4.43 a	4.63 b	5.20 c	5.50 d	4.88 B	5.10 C	4.70 A	5.07 C

Explanation: A—control object (without fungicide protection), B—two fungicide treatments, C—three fungicide treatments, D—four fungicide treatments; N₀—no nitrogen fertilisation (control object), N₁—70 kg ha⁻¹, N₂—100 kg ha⁻¹, N₃—130 kg ha⁻¹. The same letter means that it is not significantly different (p ≤ 0.05). Small letters indicate differences between nitrogen fertilisation. Capital letters indicate differences between crop protection.

). With increasing doses of nitrogen fertiliser, there was an increase in the grain content of all the amino acids tested. Fungicide protection varied in the grain content of Asp, Glu, Pro, Gly, Cys-A, Sulf. met., Phe, Lys and Arg. However, no clear trends could be identified, as the amino acid content did not increase with increasing crop protection.

The Zeleny sedimentation index of spelt wheat grain differed significantly between the variants of chemical crop protection and nitrogen fertilisation, as well as in the interaction of both factors (

Table 6. Zeleny sedimentation index [ml] of spelt wheat grain cv. ‘Rokosz’ in relation to crop protection and nitrogen fertilisation—mean for 2019–2021.

Crop Protection	Nitrogen Fertilisation				Mean
	N0	N1	N2	N3
A	25.39 ± 1.95	21.88 ± 2.83	23.15 ± 1.74	26.46 ± 3.16	24.22 ± 2.10
B	17.17 ± 2.51	19.17 ± 0.68	21.05 ± 1.29	27.50 ± 3.22	21.22 ± 4.47
C	20.54 ± 0.88	22.57 ± 1.46	20.25 ± 0.95	29.12 ± 2.33	23.12 ± 4.13
D	19.89 ± 1.25	19.21 ± 0.79	17.49 ± 0.66	17.08 ± 1.17	18.42 ± 1.35
Mean	20.75 ± 3.42	20.71 ± 1.77	20.49 ± 2.34	25.04 ± 5.41
HSD (p ≤ 0.05)	for crop protection				0.216
	for nitrogen fertilisation				0.552
	for interaction crop protection × nitrogen fertilisation				0.648

Explanation: A—control object (without fungicide protection), B—two fungicide treatments, C—three fungicide treatments, D—four fungicide treatments; N₀—no nitrogen fertilisation (control object), N₁—70 kg ha⁻¹, N₂—100 kg ha⁻¹, N₃—130 kg ha⁻¹.

). When analysing the chemical protection of the canopy, significant differences were observed between all variants applied. Zeleny’s sedimentation index reached the highest value in the object where no fungicides were applied and reached the lowest value (18.42 mL) in the variant with four fungicide treatments (D). The highest Zeleny sedimentation index was found in the highest dose of the ammonium nitrate variant.

Through analysis of the factor interactions, it was found that variants A, B and C had, significantly, the highest value in regard to the Zeleny sedimentation index after the highest dose of ammonium nitrate was applied.

The Zeleny sedimentation index was significantly modified by the weather conditions (Figure 5). The highest value was found in the first year of the study (2019), which was 15% and 13% higher than in 2020 and 2021, respectively.

Statistical analysis showed significant differences in the starch content of wheat grains as a function of crop protection, nitrogen fertilisation and the interaction between the two factors (

Table 7. Starch content [%] in the grain of spelt wheat cv. ‘Rokosz’ depending on crop protection and nitrogen fertilisation—mean for 2019–2021.

Crop Protection	Nitrogen Fertilisation				Mean
	N0	N1	N2	N3
A	54.78 ± 0.44	55.12 ± 0.45	55.35 ± 0.86	54.21 ± 0.81	54.87 ± 0.50
B	55.63 ± 0.73	55.44 ± 0.55	55.44 ± 0.37	54.42 ± 0.81	55.23 ± 0.55
C	55.23 ± 0.88	54.99 ± 0.52	55.77 ± 0.21	54.67 ± 0.95	55.17 ± 0.46
D	55.51 ± 0.80	55.74 ± 0.12	55.94 ± 0.71	56.12 ± 0.21	55.83 ± 0.26
Mean	55.29 ± 0.38	55.32 ± 0.34	55.63 ± 0.28	54.86 ± 0.86
HSD (p ≤ 0.05)	for crop protection				0.128
	for nitrogen fertilisation				0.342
	for interaction crop protection × nitrogen fertilisation				0.397

Explanation: A—control object (without fungicide protection), B—two fungicide treatments, C—three fungicide treatments, D—four fungicide treatments; N₀—no nitrogen fertilisation (control object), N₁—70 kg ha⁻¹, N₂—100 kg·ha⁻¹, N₃—130 kg ha⁻¹.

). The application of fungicides increased the starch content compared to the plot without crop protection. The highest starch content (55.83%) was found in the grain from the plot that had received four fungicide treatments. After the application of the highest dose of ammonium nitrate, the lowest starch content in the grain was observed (54.86%). This parameter was statistically identical in the other nitrogen fertilisation treatments. Under the conditions of a fourfold fungicide treatment and the highest dose of nitrogen fertiliser, the highest starch content in spelt wheat grain was observed. Grain from N₃ plots without chemical protection and after two fungicide treatments had the lowest starch content.

Chemical crop protection did not result in significant differences in the content of insoluble dietary fibre in spelt wheat grains (

Table 8. Insoluble dietary fibre content [%] in the grain of spelt wheat cv. ‘Rokosz’ in relation to crop protection and nitrogen fertilisation—mean for 2019–2021.

Crop Protection	Nitrogen Fertilisation				Mean
	N0	N1	N2	N3
A	10.70 ± 0.17	10.94 ± 0.52	10.96 ± 0.24	11.48 ± 0.34	11.02 ± 0.28
B	11.20 ± 0.26	10.29 ± 0.17	11.29 ± 0.31	11.09 ± 0.21	10.97 ± 0.40
C	10.96 ± 0.19	11.10 ± 0.24	11.10 ± 0.15	11.50 ± 0.31	11.16 ± 0.20
D	10.95 ± 0.32	11.43 ± 0.41	10.47 ± 0.39	11.84 ± 0.24	11.17 ± 0.51
Mean	10.95 ± 0.20	10.94 ± 0.48	10.95 ± 0.35	11.48 ± 0.31
HSD (p ≤ 0.05)	for crop protection				ns
	for nitrogen fertilisation				0.150
	for interaction crop protection × nitrogen fertilisation				0.462

Explanation: A—control object (without fungicide protection), B—two fungicide treatments, C—three fungicide treatments, D—four fungicide treatments; N₀—no nitrogen fertilisation (control object), N₁—70 kg ha⁻¹, N₂—100 kg·ha⁻¹, N₃—130 kg ha⁻¹; ns—no significant difference between treatments at p ≤ 0.05.

). The highest level of this component was observed in the four fungicide treatments (11.17%), while the lowest level was observed after the application of two fungicides (10.97%). The application of the highest dose of ammonium nitrate significantly increased the content of insoluble fibre in spelt hay compared to the other fertilisation treatments (N₀, N₁, N₂). After the application of 70 kg N·ha⁻¹ two fungicide treatments, the spelt grain, significantly, was the least rich in dietary fibre (10.29%), whereas, after the highest dose of ammonium nitrate and four fungicide treatments, it was the richest (11.84%).

The applied chemical crop protection did not significantly affect the variation in the soluble dietary fibre content in spelt wheat grain (

Table 9. Soluble dietary fibre content [%] in the grain of spelt wheat cv. ‘Rokosz’ in relation to crop protection and nitrogen fertilisation—mean for 2019–2021.

Crop Protection	Nitrogen Fertilisation				Mean
	N0	N1	N2	N3
A	2.09 ± 0.11	1.73 ± 0.09	2.02 ± 0.08	1.76 ± 0.15	1.90 ± 0.16
B	1.98 ± 0.13	1.69 ± 0.13	1.92 ± 0.17	1.63 ± 0.14	1.80 ± 0.15
C	2.07 ± 0.25	1.46 ± 0.18	2.03 ± 0.12	1.91 ± 0.19	1.87 ± 0.24
D	2.01 ± 0.17	2.04 ± 0.21	2.11 ± 0.19	1.74 ± 0.14	1.97 ± 0.14
Mean	2.04 ± 0.05	1.73 ± 0.24	2.02 ± 0.08	1.76 ± 0.12	-
HSD (p ≤ 0.05)	for crop protection				ns
	for nitrogen fertilisation				0.153
	for interaction crop protection × nitrogen fertilisation				ns

Explanation: A—control object (without fungicide protection), B—two fungicide treatments, C—three fungicide treatments, D—four fungicide treatments; N₀—no nitrogen fertilisation (control object), N₁—70 kg ha⁻¹, N₂—100 kg ha⁻¹, N₃—130 kg ha⁻¹; ns—no significant difference between treatments at p ≤ 0.05.

). Sites with four fungicide treatments had the grain with the highest soluble fibre abundance (1.97%), while the least abundant grain was observed in sites with two fungicide treatments (1.80%). Soluble fibre content was significantly influenced by nitrogen fertilisation. The most abundant grain in this component was found in the variant in which no ammonium nitrate was applied (2.04%), while the least abundant grain was found after the application of 70 kg N ha⁻¹ (N₁).

The experiment showed that chemical protection of the canopy did not significantly affect the fat content of the spelt wheat grain (

Table 10. Fat content [%] in the grain of spelt wheat cv. ‘Rokosz’ depending on crop protection and nitrogen fertilisation—mean for 2019–2021.

Crop Protection	Nitrogen Fertilisation				Mean
	N0	N1	N2	N3
A	1.56 ± 0.02	1.77 ± 0.05	1.81 ± 0.03	1.75 ± 0.02	1.72 ± 0.10
B	1.69 ± 0.05	1.78 ± 0.06	1.85 ± 0.05	1.86 ± 0.07	1.80 ± 0.07
C	1.65 ± 0.05	1.76 ± 0.02	1.78 ± 0.05	1.66 ± 0.02	1.71 ± 0.06
D	1.60 ± 0.06	1.77 ± 0.08	1.80 ± 0.04	1.72 ± 0.04	1.72 ± 0.08
Mean	1.63 ± 0.06	1.77 ± 0.01	1.81 ± 0.03	1.75 ± 0.08
HSD (p ≤ 0.05)	for crop protection				ns
	for nitrogen fertilisation				0.098
	for interaction crop protection × nitrogen fertilisation				ns

Explanation: A—control object (without fungicide protection), B—two fungicide treatments, C—three fungicide treatments, D—four fungicide treatments; N₀—no nitrogen fertilisation (control object), N₁—70 kg ha⁻¹, N₂—100 kg ha⁻¹, N₃—130 kg ha⁻¹; ns—no significant difference between treatments at p ≤ 0.05.

). The highest fat content was observed in the object with two fungicide treatments (1.80%). The same result of 1.72% was found with treatments A and D, and the lowest fat content was observed in the plot with three fungicide treatments (1.71%). Nitrogen fertilisation caused significant differences in the fat content of spelt wheat. The lowest fat content (1.63%), significantly different from the other objects, was observed in the variant without ammonium nitrate fertilisation.

Chemical crop protection and nitrogen fertilisation had no significant effect on the content of o-dihydroxyphenols in spelt wheat grain (

Table 11. O-dihydroxyphenol content [%] in the grain of spelt wheat cv. ‘Rokosz’ in relation to crop protection and nitrogen fertilisation—mean for 2019–2021.

Crop Protection	Nitrogen Fertilisation				Mean
	N0	N1	N2	N3
A	0.13 ± 0.02	0.15 ± 0.05	0.11 ± 0.01	0.26 ± 0.07	0.16 ± 0.06
B	0.18 ± 0.01	0.18 ± 0.02	0.18 ± 0.01	0.19 ± 0.05	0.18 ± 0.01
C	0.16 ± 0.02	0.13 ± 0.06	0.04 ± 0.04	0.46 ± 0.02	0.20 ± 0.16
D	0.15 ± 0.03	0.14 ± 0.01	0.12 ± 0.03	0.13 ± 0.04	0.14 ± 0.01
Mean	0.16 ± 0.02	0.15 ± 0.02	0.11 ± 0.06	0.26 ± 0.014
HSD (p ≤ 0.05)	for crop protection				ns
	for nitrogen fertilisation				ns
	for interaction crop protection × nitrogen fertilisation				ns

Explanation: A—control object (without fungicide protection), B—two fungicide treatments, C—three fungicide treatments, D—four fungicide treatments; N₀—no nitrogen fertilisation (control object), N₁—70 kg ha⁻¹, N₂—100 kg ha⁻¹, N₃—130 kg ha⁻¹; ns—no significant difference between treatments at p ≤ 0.05.

). The content of this component ranged from 0.04% after the application of three fungicide treatments and 100 kg ha⁻¹ N to 0.26% in the variant without chemical protection and the highest dose of nitrogen.

3.2. Physical Parameters of the Grain

In each of the spelt wheat crop protection variants, irrespective of nitrogen fertilisation, grains with a diameter of 2.8–2.5 mm prevailed, with object B recording the highest proportion—over 48% (Figure 6). Grains with a diameter of less than 1.8 mm had the smallest percentage share. The variant without fungicide protection was characterised by a significantly higher proportion of fractions with a diameter of above 2.8 mm than the other objects.

Grains with a diameter of 2.8–2.5 mm had the highest percentage share in each of the nitrogen fertilisation variants regardless of crop protection (Figure 7). In the object where the highest dose of ammonium nitrate was applied, a more than 50 percent share of this fraction was observed. Each variant was characterised by about 1 percent of grains featuring a diameter below 1.8 mm and about 30 percent of the grains featuring a diameter of 1.8–2.2 mm.

Statistical analysis showed significant differences in the spelt wheat grain fraction of the spelt wheat above 2.5 mm in regard to crop protection, nitrogen fertilisation and the interaction between the factors (

Table 12. Grain fraction of the spelt wheat cv. ‘Rokosz’ above 2.5 mm [%] in relation to crop protection and nitrogen fertilisation—mean for 2019–2021.

Crop Protection	Nitrogen Fertilisation				Mean
	N0	N1	N 2	N3
A	64.74 ± 1.88	62.51 ± 2.13	60.95 ± 2.07	63.70 ± 1.54	62.97 ± 1.63
B	65.52 ± 1.90	63.38 ± 6.38	59.85 ± 3.92	69.32 ± 2.93	64.51 ± 3.96
C	65.85 ± 4.33	59.51 ± 4.90	64.27 ± 2.41	61.89 ± 3.21	62.88 ± 2.77
D	64.42 ± 2.43	64.63 ± 2.68	58.76 ± 3.13	59.90 ± 1.62	61.92 ± 3.04
Mean	65.13 ± 0.66	62.51 ± 2.18	60.95 ± 2.38	63.70 ± 4.05
HSD (p ≤ 0.05)	for crop protection				0.896
	for nitrogen fertilisation				1.402
	for interaction crop protection × nitrogen fertilisation				2.037

Explanation: A—control object (without fungicide protection), B—two fungicide treatments, C—three fungicide treatments, D—four fungicide treatments; N₀—no nitrogen fertilisation (control object), N₁—70 kg ha⁻¹, N₂—100 kg ha⁻¹, N₃—130 kg ha⁻¹.

). Grain fraction above 2.5 mm was highest after two fungicide treatments (64.51%) and lowest after four fungicide treatments (61.92%). The plot without nitrogen fertilisation had, significantly, the highest grain fraction of spelt wheat above 2.5 mm (65.13%) compared to the other variants. The lowest value of this parameter, significantly different from the others, was observed after the application of 100 kg N ha⁻¹. In treatments A, B and D, the lowest grain fraction of spelt wheat above 2.5 mm was found after the application of the N₂ dose, while the highest (69.32%) was found in the treatments with the highest nitrogen dose and double fungicide treatment.

4. Discussion

The increased interest in spelt wheat has made it a subject of research for many authors. One of the main reasons for the revival of this type of wheat in recent years is its tolerance to growing conditions and its ability to tolerate unfavourable environmental factors, which allows it to be grown without excessive use of industrial means of production [40,41]. Compared to common wheat, spelt wheat has a higher protein content, higher gluten content and higher falling index, but its gluten quality and sedimentation index are lower. In addition, this species has a higher content of some minerals than common wheat [1,28,29,33,42,43,44]. In many studies, the protein content of spelt grains ranges from 13.0 to 16.5% [1,28,33,42,43], while Gomez-Becerra et al. [45] showed a protein content of 18.5–21.8% of dry matter, and this amount was stable under different environmental conditions. In our own studies, the amount of protein in grain was usually lower than in other studies. Under the same climatic conditions, Rachoń et al. [46] showed that the average content of this component in the variety Witras was 16.6%, with a nitrogen fertilisation of 150 kg per hectare.

Wang et al. l’s research [31] suggests that breeding varieties suitable for specific environments is the most promising approach to further improving the grain quality of spelt wheat. The composition of spelt wheat grain is influenced by genetic and environmental factors. Spelt wheat is genetically diverse, and old varieties differ from their new breeding lines in terms of grain quality. This fact must be taken into account in the case of all kinds of references and comparisons of different groups or varieties of spelt wheat.

The chemical composition of agricultural crops is determined not only by their genetic characteristics but also by a wide range of agrotechnical, soil, climatic and developmental factors. The effects of these factors can vary greatly depending on the component being assessed or the region in which the research was carried out [47,48,49,50,51]. For this reason, the results of the trials carried out may differ from those of other researchers.

Among weather factors, the greatest influence on the formation of the quality features of wheat grain is the amount of precipitation and temperature in the period from earing to harvest. For the formation of a large amount of gluten proteins, sunny weather with moderate precipitation and high air temperatures are the most favourable. The manuscript states that the dry year 2019 influenced the increase in protein concentration in spelt wheat. The highest content of protein content, as cited in research by Lacko-Bartošova [52], was determined in a warm year with insufficient precipitation, and similar observations were made by Bojňanská i Frančáková [53]. The conducted studies also revealed the influence of weather conditions on the gluten content in the analysed spelt grain samples, and the highest gluten content was found in the first year of the study (2019). Similarly, Bojňanská and Frančáková [53] noted that the highest gluten content in their samples of spelt grain came from an extremely dry year. The study of Lacko-Bartošova et al. [54] was similar, as the highest gluten in their samples was found in a year with higher temperatures and an insufficient or normal distribution of rainfalls.

The productivity of this species and the quality of grains is significantly influenced by the sowing technology, dose and timing of fertiliser application, as well as plant protection against agrophages [2,15,19,34,40,55,56]. The aim of spelt wheat cultivation is to produce raw material of the highest possible quality, as the main use of this crop is the production of high-quality food [25,33]. In order to preserve the high nutritional qualities of spelt wheat, appropriate cultivation technology should be selected. Appropriate cultivation guarantees a high-quality raw material [40,55].

Many publications emphasise that spelt wheat is tolerant to growing conditions and does not require intensive protection; therefore, it is recommended for cultivation on organic farms [28,34,57]. In the studies by Kwiatkowski et al. [57], spelt grown on an organic farm was characterised by a higher content of total dietary fibre in the grain (organic system—150.9 g kg⁻¹, conventional system—136.1 g kg⁻¹), o-dihydroxyphenol (organic system—2.00 g kg⁻¹, conventional system—1.68 g kg⁻¹) and macro- and microelements (except nitrogen), and it had a positive effect on the amino acid composition of the protein compared to the conventional system. Studies by Kowalska et al. [58] showed that Triticum aestivum L. subsp. spelta cultivated in an organic system had a high content of total phenolic acids and alkylresorcinol derivatives in grain and husk, significantly higher than Triticum aestivum L. subsp. aestivum, Triticum monococcum and Triticum dicoccum. Gawęda et al. [15] also confirmed the possibility of growing spelt under extensive conditions. Studies carried out in the same soil and climatic conditions as those presented in this article showed that, in the Rokosz variety, the gluten content in the variant with full chemical protection was significantly lower than in the variant with only herbicide use and in the harrowed object, but it did not differ significantly from the object without protection. It was shown that pro-ecological care had a more favourable effect on the characteristic under consideration than the chemical protection of the field. For Schwabenpelz, although no significant differences were found, pro-ecological technologies also had a positive effect on the gluten content in the grain. Although many studies indicate that spelt tolerates low or no canopy protection well, the results of the study indicate that intensifying fungicide canopy protection has a positive effect on the protein, gluten, starch and amino acid composition of the grain. However, it had no significant effect on the abundance of fat, insoluble and soluble dietary fibre and o-dihydroxyphenols in the grain. The positive effect of chemical protection on the grain quality of spelt wheat was also confirmed by other authors. In a study by Pospišil et al. [56], they showed that the application of fungicide protection increased the protein content of the grain. Andruszczak [40] found that, after applying full chemical protection to the spelt wheat canopy, the kernels were characterised by higher protein content and had a higher Zeleny sedimentation index. Rachoń et al. [59] demonstrated that the intensification of chemical plant protection beneficially affected the chemical composition of spelt wheat, increasing the grain protein content, whereas the study by Kwiecińska-Poppe et al. [50] revealed that there was no such relationship. In our study, canopy protection also differentiated the amino acid composition of the protein contained in spelt wheat acids depending on the intensity of canopy protection was prot kernels. Such trends were also confirmed in a study by Biel et al. [51] where variations in the levels of acid content were found. Moreover, as shown by Kraska et al. [25], the amino acid composition in spelt wheat grain depends on the developmental stage of the kernels. The authors showed a higher content of Asp, Thr, Ser, Gly, Ala, Cys, Val, Met, Ile, Leu, Phe, Lys, and Trp in grains at the milk maturity stage, indicating the possibility of using green grain in the human diet. The studies conducted indicate that the use of chemicals in crops has a beneficial effect on plant health, reduces stress and contributes to the improvement of technological parameters. However, it should be emphasised that, in varieties with low tolerance to the active substance of the agent used, changes in the course of many biochemical processes may occur, leading to disturbances in the accumulation of nutrients and deterioration of grain quality characteristics [60,61,62].

The fertilisation of crops has a key role to play in shaping the quality of agricultural products [63,64]. According to Suchowilska et al. [65], spelt responds poorly to high doses of nitrogen and, unlike bread wheat, high doses of nitrogen fertiliser do not significantly improve yield. In the conducted study, increasing the nitrogen dose to 130 kg ha⁻¹ resulted in an improvement in most spelt wheat grain quality parameters. In a study by Podolska et al. [66], significant differences in the content of the total protein in spelt wheat grain were recorded between the objects: control and with the lowest dose of nitrogen fertiliser and the variant where 120 kg N ha⁻¹ was applied. An increase of up to 13.9% in the total protein content of the grain was observed. Similar correlations were proved by Stępień et al. [67]. The authors demonstrated a positive effect of mineral fertilisation on protein content compared to objects without fertilisation. In the study by Andruszczak [55], increasing the nitrogen dose from 50 to 80 kg ha⁻¹ contributed to a 2.3% increase in protein content in the grain. Podolska et al. [66] also found that increasing the nitrogen fertiliser dose resulted in a significant increase in the gluten content of spelt wheat grain, which was 27.4% in the no-fertiliser facility and 35.5% in the variant in which 120 kg N ha⁻¹ was used. Hury et al. [68] showed a significant increase in the Zeleny index value after the application of nitrogen fertiliser. In the control site, it was 14.4 mL, and this increased to 18.2 mL after the application of 100 kg N ha⁻¹. Similar correlations were found in the conducted studies. Also, Stępień et al. [67] and Andruszczak [52] found that an increase in the sedimentation rate occurred with an increase in nitrogen fertilisation, although the value of this parameter was much higher in the studies of these authors. Andruszczak [55] found a Zeleny sedimentation index of 68.9 mL after the application of 50 kg N ha⁻¹ and 71.3 mL after the application of 80 kg N ha⁻¹, while, in the study of Stępień et al. [67], the range of this parameter was from 39.13 to 41.18 mL. In the study by Biel et al. [69], there were no significant differences in the soluble and insoluble dietary fibre contents under the influence of different nitrogen fertiliser doses, while, in the present study, the application of different nitrogen doses differentiated these parameters. The fact that spelt responds positively to a good location and high soil nutrient content was confirmed by the research of Wanic et al. [70]. Grains collected from spelt fields after winter rape and peas had higher protein and wet gluten contents, higher Zeleny indices, falling number values, and higher N, P, Fe and Zn contents than those collected from spelt fields after cereals.

5. Conclusions

The present study showed that production intensification has an effect on the grain quality parameters of spelt wheat cultivar ‘Rokosz’ grown under south-eastern Polish conditions. Intensification of fungicide crop protection had a positive effect on the protein, gluten and starch content of spelt wheat grains. These parameters increased their values after increasing the number of fungicide treatments from two to four. Increasing the nitrogen dose from 70 to 130 kg ha⁻¹ increased the abundance of total protein, gluten, soluble dietary fibre, insoluble dietary fibre and fat in the grains. It also had a positive effect on the Zeleny sedimentation index and the amino acid content of the grain. The studies conducted did not clearly confirm the beneficial effect of intensified crop protection and mineral fertilisation on the plumpness of spelt grain. Due to the favourable response of spelt variety ‘Rokosz’ to fungicide protection and nitrogen fertilisation, this variety should be recommended for cultivation, especially with integrated technology, where moderate use of chemical plant protection products and mineral fertilisers is recommended. Other new varieties of spelt that have some of the same characteristics as common wheat may also be covered by this recommendation.