Geographical and Soil-Based Assessment of Yield and Fiber Quality in Two Flax Varieties in Central–Eastern Poland Using the Flax Value Chain Approach

Abstract

Flax cultivation is influenced by geographical conditions and soil properties, affecting yield and fiber quality. This study examines the performance of two fiber flax varieties, Artemida and Hermes, in 2021–2023 in central–eastern Poland’s agroclimatic and soil conditions using a value chain approach. Field trials were conducted in soils of varying fertility under a continental climate, employing a randomized block design with four replications. Flax straw underwent dew-retting, and long fibers were extracted through laboratory scutching. Results showed significant differences between the varieties. Artemida achieved higher straw yields, particularly in moderately fertile soils, while Hermes produced a higher proportion of long fibers and adapted better to less-fertile soils. Hermes fibers were thinner and more delicate, whereas Artemida fibers were coarser and stronger. The average straw yield of the Artemida variety was higher by 1.5 t ha⁻¹ than that of the Hermes variety. The yield and quality of fiber were determined by soil fertility and climate, and the genotype–environment interaction was of the greatest importance. These findings provide valuable insights for farmers and stakeholders in selecting suitable flax varieties for different soil and climatic conditions in central–eastern Poland. The value chain approach also supports optimizing cultivation practices and improving the economic sustainability of flax production.

1. Introduction

There are about 2000 species of fiber plants in agroecosystems globally, but only a small fraction is used practically [1]. Annual production of key fiber crops such as cotton, flax, jute, agave, sisal, abaca, and ramie reaches 29.5 million tons [2]. Climatic factors, especially temperature and precipitation, largely determine the yield and susceptibility to pests and diseases [3]. In cotton cultivation, high temperatures increase water stress, while elevated CO₂ concentration can stimulate growth and development, potentially increasing yields by intensifying photosynthesis and reducing bud shedding [4]. Uneven rainfall distribution threatens jute crops with early spring drought, which negatively affects nutrient uptake and production [5].

Flax (Linum usitatissimum L.), a self-pollinating annual [1], originated in the Near East and exists mainly in cultivated fiber and oil forms. Fiber flax (60–80 cm) has a shallow root system and small seed capsules [2], with fiber cells ranging from 6 to 65 mm and technical fiber lengths of 90–125 cm [2,6]. Yields are 0.4–1.2 t ha⁻¹ for seeds and 4.0–6.5 t ha⁻¹ for straw [3,4]. In Europe, “flax” typically refers to fiber varieties, and “linseed” to flax oil. Cultivated for over 10,000 years [5,6], fiber flax cultivation in Europe declined in the 20th century but rebounded in the 1990s [7,8]. The composition of flax fiber is approximately 75% cellulose, 5% hemicellulose, 4% lignin, 3% fats and waxes, 0.5% ash, and 12.5% water [7,8,9]. Modern cultivation focuses on long-straw, high-fiber varieties [10,11,12] used in various industries [13,14,15,16], including textiles and paper [17,18,19,20]. Linseed is used in food and feed [21,22,23], and its oil is rich in beneficial omega-3 fatty acids [24,25,26]. Flax stalks are pulled to maximize the fiber length [27], with different parts used for varying yarn qualities. Quality assessment is vital [28].

Flax production, despite its high energy and pesticide demand, is characterized by a relatively low impact on global warming, eutrophication, and acidification [29]. The introduction and popularization of flax is important for the globalization of agricultural production and for counteracting the decline in crop diversity [30]. In the context of the priority of climate protection and biodiversity over economic growth, it is necessary to slow down the chain of goods and services and minimize the transformation of ecosystems [31]. Various fractions of flax—fiber, shive, and seeds—are used in the production of bioenergy, activated carbon, wax, bioproducts, industrial and food oils, aromatic extracts, and feed [32]. Flax fibers are used in the production of gypsum plasterboard [33] and reinforced concrete [34]. Flax shives are a raw material for bioethanol production [35], and the lignocellulose contained in them is a potential source of cellulosic ethanol [36]. Flaxseed is key in the production of industrial and edible oils, including as a component of varnishes, paints, sealants, and waxes for wood and concrete [37]. Chickens fed flaxseed produce eggs rich in omega-3 fatty acids [38]. Natural flax fibers are attractive in composites due to their low cost, biodegradability, relatively high strength, low abrasion, safety, recyclability, and the possibility of waste reuse [32]. In the context of global challenges related to climate change, which increasingly affect European agricultural systems, it is crucial to search for sustainable and resilient strategies for the production of fiber crops. Recent studies [3,4,5,39,40] indicate significant changes in fiber yields and quality in different regions of Europe under the influence of changing atmospheric and geographical conditions.

Central–eastern Poland is characterized by a more continental climate than the western part of the country, with larger annual temperature amplitudes and generally lower average precipitation, which is concentrated in the summer [41]. This region also has a longer period of snow cover and more frosty days [40]. These specific climatic conditions, different from other regions of Poland, are of significant importance for flax cultivation. The dominant soils of central–eastern Poland are podzols, lessives, browns, and rendzinas [42]. These moderately fertile and permeable soils have historically been conducive to flax cultivation, which prefers moderate moisture and good drainage, shaping local agricultural traditions. Understanding this soil specificity is crucial for optimizing flax production.

In this context, the application of the value chain approach (VCA) offers a comprehensive perspective on the optimization of flax production from sowing, through harvesting and processing, to the final product. VCA enables the identification of key factors influencing the yield and quality of fibers at each stage as well as the integration of the activities of different actors in the chain in order to increase the efficiency and sustainability of production [43].

The results of this study have a significant impact on decisions regarding the sustainable development of flax cultivation in the central–eastern region of Poland and potentially in other areas with similar conditions. By identifying the optimal agrotechnical practices and flax varieties adapted to local soil and climate conditions, we will contribute to increasing the crops’ resilience to climate change and minimizing their negative impact on the environment. This study is also closely linked to the implementation of several Sustainable Development Goals of the UN Agenda 2030 [44], in particular, the following:

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SDG 2 (Zero Hunger): by optimizing yields and increasing the efficiency of agricultural production.

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SDG 12 (Responsible Consumption and Production): by promoting sustainable flax cultivation and processing practices.

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SDG 13 (Climate Action): by exploring climate change adaptation strategies in agriculture [44].

The potential beneficiaries of the results of this research are primarily farmers, who will receive practical advice on the selection of flax varieties and cultivation methods; representatives of the textile industry, who will gain access to raw material of optimal quality; and decision makers, who will be able to make more informed decisions in the field of agricultural and environmental policy.

The main objective of the study is to assess the yield and fiber quality of two selected fiber flax varieties grown in central–eastern Poland using the flax value chain approach. This objective includes identifying the impact of local soil and geographic conditions on the yield and fiber quality parameters of both varieties. Additionally, the study aims to determine the potential of each variety in the context of optimizing individual stages of the flax value chain in this region. An alternative research hypothesis was put forward to the null hypothesis.

H₀ (Null Hypothesis): 

There are no statistically significant differences between the two studied fiber flax varieties in terms of yield and fiber quality in the climatic and soil conditions of central–eastern Poland considering individual stages of the value chain. Furthermore, there is no significant relationship between local soil and geographic conditions and the yield and fiber quality of the studied varieties.

H₁; (Alternative Hypothesis): 

There are statistically significant differences between the two tested fiber flax varieties in terms of yield and/or fiber quality in the climatic and soil conditions of central–eastern Poland, and these differences are visible in the analysis of individual stages of the value chain.

2. Materials and Methods

The analysis of the results was based on a field experiment conducted in 2021–2023 in the town of Gródki. The experiment was established using the randomized block method in four replications. The area of 1 object for harvesting was 0.5 ha. The objects of the experiment were the fiber flax varieties Artemida and Hermes.

Gródki is in the Roztocze region, where podzolic, lessive, and brown soils dominate with varying degrees of acidity [45]. Depending on the altitude and microtopography, the soil can be either fertile or require pH improvement. West Roztocze is characterized by a strong relief, with numerous valleys, ravines, and hills. The strongholds are located on two opposite hills that form a valley at their fall. The conditions for agricultural work there are difficult due to the terrain. Cultivated fields are exposed to water erosion and weathering [45,46].

2.1. Characteristics of Varieties

Artemida, a variety bred at the IWN Stary Sielec Experimental Station near Rawicz, comes from the crossbreeding of the very resistant Natasja variety with the moderately susceptible Tajga variety. It entered the List of Original Cultivated Plant Varieties in 1996. The features of this variety include high resistance to diseases and lodging. The vegetation period of Artemida is approx. 104 days. This variety is characterized by high-quality, long fibers. Artemida is one of the most popular varieties in the Lublin region, although its area is decreasing in favor of Western European varieties [47].

Hermes is a French variety, bred in 1992 by Terre De Lin, a leader in flax plant breeding in terms of productivity and disease resistance. This variety is characterized by the high productivity of long fibers, high content of single fibers, and their high quality [11].

2.2. Research Conditions

2.2.1. Geographical Location

Gródki is in Roztocze, in the commune of Turobin in the southeastern part of Poland (50°46′36″ N, 22°41′01″ E) (Figure 1) [45].

This region is also characterized by the presence of forest areas, which affect specific soil conditions and microclimates that are conducive to the growth of certain plant species [45].

Topography and terrain: The terrain is varied. The area is slightly undulating, with numerous hills and valleys, which can affect natural soil drainage and microclimatic conditions. The terrain rising in Roztocze is beneficial for agriculture but can also cause specific challenges in terms of irrigation and protection against erosion [45].

Topography of Gródki and Turobin Commune: Gródki, located within Roztocze (Figure 2), is characterized by a varied terrain. It is an upland region intersected by hills, valleys, and loess ravines. It is slightly undulating terrain; small differences in height can be expected over relatively short distances, creating a hilly landscape. Altitudes: Typical heights in Roztocze range from 200 to 400 m above sea level (Figure 1). Influence of loess: The presence of loess contributes to the characteristic relief, including the formation of steep-sided ravines. The topography of Gródki and the surrounding area of the Turobin Commune is typical of Roztocze, characterized by a varied landscape with hills and valleys [45,46].

The varied relief of Roztocze, with slightly undulating terrain and numerous hills and valleys, influences drainage and microclimate. The hills are conducive to agriculture through better drainage, air circulation, and solar exposure, although they can make irrigation difficult and increase the risk of erosion. The surface is rich in glacial deposits (tiles, sand), with groundwater, and underneath them there are Upper Cretaceous carbonate rocks [46,47,48,49,50,51].

Hypsometric map (Figure 3) shows the varied terrain of the Gródki and Huta Turobin areas in the Lublin Upland in southeastern Poland.

Map characteristics: Hypsometry: The vertical color scale in the upper left corner indicates altitudes from less than 200 m above sea level (green) to over 350 m above sea level (red). The shading of the terrain, with lighting from the northwest, highlights the steepness of the slopes and the depth of the valleys. Terrain features: The area is characterized by numerous steep ridges and deep, branching valleys and gullies, typical of loess areas subject to intensive erosion. There are flattened plateaus between them. Cartographic elements: The map contains a geographic coordinate grid and a linear scale (2 cm = 2 km). The towns of Gródki and Huta Turobin are clearly marked. The hypsometric scale serves as a legend. Summary: The map effectively illustrates the complex and highly diversified morphology of the terrain, dominated by deep valleys and ravines characteristic of loess regions (Figure 3 and Figure 4).

The land surface in this area is rich in glacial deposits, mainly tills and sandy sedimentary formations, which hold groundwater [52]. Water circulation in the zone of active water exchange occurs in Upper Cretaceous carbonate rocks formed from siliceous chalk, marls, and rocks. In the context of the FAO WRB [53] classification, the soils of this area represent different units depending on the dominant parent material (glacial sediments, carbonate rocks), drainage conditions (related to the diversified terrain), and soil-forming processes. It can be assumed that they contain Cambisols (on weathered rocks of various rocks, including glacial sediments), Luvisols (on tills, showing clay displacement), and in valleys and areas with difficult drainage, perhaps Gleysols. Soils developing on carbonate rocks may show features of Calcisols or Leptosols, depending on the degree of development and thickness [42,53].

Water availability: There are numerous streams, rivers, and creeks in the vicinity of Gródki which can affect the availability of water during periods of drought, as well as the formation of the microclimate within the fields [45,54,55].

Infrastructure availability: Gródki is well connected to the rest of the region, with access to the main roads connecting the Turobin Commune with larger urban centers, which ensures convenient transport of crops and access to resources necessary for conducting agricultural activities [45].

This is a town with a favorable geographical location in Roztocze, in the commune of Turobin, in areas with a varied topography and fertile soils that are conducive to a variety of agricultural crops. High soil quality and a specific microclimate in the Roztocze region are the basis for the effective cultivation of various crops, including cereals, fiber plants, root crops, legumes, vegetables, and fruit plants [45,46]. The climatic and soil conditions in this region enable effective agricultural production, and the presence of surface water affects the natural irrigation of fields. The high quality of the soil and microclimate in this area (Roztocze) are the basis for effective cultivation of crops such as flax in this part of Poland [45,46].

2.2.2. Agrotechnics Conditions

Fiber flax was grown in a seven-field crop rotation (Table 1). To plan the crop rotation for fiber flax for 2021–2023, the principles of crop rotation were considered, such as the following:

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Avoiding growing flax in succession (due to diseases and soil depletion).

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Succession of plants with different nutritional requirements and impacts on soil structure.

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Maintaining an appropriate balance of nutrients in the soil.

Table 1. Crop rotation scheme for 7 fields (2021–2023).

Field No.	2021	2022	2023
1	Flax	Wheat	Rape
2	Potato	Barley	Onion
3	Barley	Sugar beet	Wheat
4	Sugar beet	Barley	Flax
5	Wheat	Rape	Barley
6	Sugar beet	Barley	Wheat
7	Rape	Flax	Parsley

Table 1. Crop rotation scheme for 7 fields (2021–2023).

Field No.	2021	2022	2023
1	Flax	Wheat	Rape
2	Potato	Barley	Onion
3	Barley	Sugar beet	Wheat
4	Sugar beet	Barley	Flax
5	Wheat	Rape	Barley
6	Sugar beet	Barley	Wheat
7	Rape	Flax	Parsley

Different crops in succession improve soil fertility (e.g., rapeseed and sugar beet provide organic matter and improve soil structure). Avoiding repeated crops in subsequent years minimizes the risk of diseases and pests and maintains the nutrient balance in the soil. This system allows for optimal use of the soil and ensures high yields in subsequent years [45].

In autumn, cultivation was limited to post-harvest treatments, aimed at destroying weeds, and deep pre-winter ploughing to a depth of 20–30 cm. In autumn, before winter ploughing, phosphorus–potassium fertilization was applied in accordance with the soil’s nutrient content. The following amounts of fertilizers were applied: 54.6 kg P ha⁻¹, in the form of triple superphosphate 48%, and 124.5 kg K ha⁻¹, in the form of potassium salt 60%, mixed with the soil. In spring, to limit water evaporation, harrowing was carried out with a light harrow. The next treatment was soil fertilization with nitrogen in the amount of 30 kg N ha⁻¹ and in the form of ammonium nitrate. Fertilization in this experiment was based on soil test results and recommendations for flax cultivation. Then, using a cultivation-sowing unit, sowing was carried out in the amount of 130 kg ha⁻¹ to a depth of approx. 2 cm, which ensured a density of 2300 plants ha⁻¹. Before sowing, flaxseeds were dressed against seedling blight and flax anthracnose with Oxafun T 75 DS/WS seed dressing, in the amount of 3 g·15 mL H₂O. Sowing was carried out on 18 April. To ensure the proper development of flax, protection against pests, diseases, and weeds was applied; in the experiment, care was taken to ensure proper plant protection management, and the above-mentioned agents were used. In the period from emergence to 5 cm of flax height, when the first flax long-legged beetles and flax flea beetles appeared, in the number of 5–10 pcs·m⁻², the plants were sprayed with Karate Zeon 050 CS in the amount of 0.15 dm·ha⁻¹. The treatment was repeated after 10 days. At the turn of May and June, when the first thrips appeared (harm threshold: 2 individuals on 10 plants), Karate Zeon 050 CS preparation was applied at a dose of 0.15 dm ha⁻¹ [56,57]. This treatment was repeated after 15 days. A very important agrotechnical treatment was the regulation of weed infestation in the canopy. The herbicide Glean 75 WG 15 g ha⁻¹ was used against dicotyledonous weeds in the cotyledon stage to the 2-leaf stage (at the latest, in the herringbone stage). The herbicide Targa Super 05 EC was used against monocotyledonous weeds one week after the application of the agent against dicotyledonous weeds, at a dose of 1.5 dm ha⁻¹ [56,57,58].

2.2.3. Natural Conditions

The Lublin province, where the research was conducted, is an agriculturally heterogeneous area. It is characterized by a large diversity of natural agricultural conditions, which constitute a measurable assessment of environmental elements such as soil, agroclimate, terrain, and water relations (Figure 2). The average agricultural production space index in this region is 74.1 points, and it is higher than the national average by 7.5 points (66.6 points nationally). Fiber flax was grown in western Roztocze, at an altitude of 220–225 m above sea level [45]. There is a specific microclimate here that favors flax cultivation, and farmers have grown flax here since “olden times” [45,46]. Gródki, as well as the Roztocze region, lie within the continental climate. Here, a special feature of the climate is the longest summer and winter period in the country, fluctuating within the range of approx. 100 days. The warmest months of the year are June–August, and the coldest month is January. There is a significant predominance of summer precipitation over winter. The length of the vegetation period here is about 200 days [41].

2.2.4. Soil Conditions

The agricultural land in the study area is dominated by loess soils and soils developed from chalk formations. The research was conducted on soil developed from clayey sands, defective wheat complex, quality class IIIa to IV [42,52]. Quality classes IIIa to IV specify the place of this soil in the quality hierarchy, indicating soils of medium quality, with certain limitations compared with classes I and II. It is worth noting that the soil quality classification in Poland is a national system and is not directly linked to international soil classification systems such as the FAO WRB [53]. In order to relate this soil to the FAO WRB, additional information on its soil profile, diagnostic levels, and properties would be needed. Each year before the start of the experiment, 20 soil samples were taken from the topsoil (0–20 cm) in accordance with the Polish Standard [54]. These samples, with a total mass of about 0.5 kg, were analyzed to assess several soil properties, including granulometric composition; the content of available phosphorus, potassium, and magnesium; and soil pH [55,56,57,58]. Soil pH was determined both in a solution of 1 mol KCl dm⁻³ and in water using the potentiometric method [59]. The content of available magnesium was measured using the Schachtschabel method [60], while available phosphorus was analyzed in mineral soils using the spectrophotometric method [61]. Available potassium was determined according to PN-R-04022:1996+AZ1:2002 [62]. This standard concerns the determination of the available potassium content in mineral soils by flame photometry.

Table 2. Granulometric composition of soil under flax cultivation in 2021–2023.

Years	Mechanical Fraction Content in %			Mechanical Content
	2.0–0.1 mm	0.1–0.02 mm	<0.02 mm
	(Sand)	(Silt)	(Clay)
2021	64.9	19.8	15.3	pgl
2022	65.7	22.4	11.9	glp
2023	66.8	23.2	10.0	pgl
Mean	65.8	21.8	12.4

Source: results were marked at the Chemical and Agricultural Station in Lublin according to the standards in force in the EU; pgl—light clay soil; glp—light, silty clay soil.

presents data on the agronomic category of the granulometric composition of agriculturally used soil in 2021–2023.

Granulometric Composition of Soil and Agronomic Category: In the period studied, the soil was characterized by a light texture, with a dominant sand fraction (average 65.8%). The dust content was significantly lower (average 21.8%), showing an upward trend in subsequent years. The smallest fraction was clay (average 12.4%), with a downward trend (Table 2).

The agronomic categories of the soil, confirmed in Table 2, ranged between light, loamy sand (pgl) and silty clay sand (glp). In 2022, the soil was classified as glp, which indicates a slightly higher share of the silt and clay fractions compared with 2021 and 2023, when the pgl category dominated. The observed fluctuations in the proportions of the fractions were reflected in changes in the agronomic category of the soil. In general, the tested soil was sandy–silty–clayey, with a predominance of sand (Table 2). Soil agronomic category: The soil in all years was classified as pgl, which indicates its agricultural suitability [63,64].

Table 3. Physical and chemical properties and the content of assimilable forms of P₂O₅, K₂O, and Mg.

Years	Soil Acidity		The Content of Absorbable Forms [mg·100 g−1 Air Dry Weight of the Soil]
	pHKCl	Soil Reaction	P2O5		K2O		Mg
2021	5.04	Sour	6.3	Short	22.0	High	4.5	Short
2022	5.64	Slightly sour	11.1	Mean	15.5	Mean	5.4	Mean
2023	6.37	Slightly sour	18.9	High	16.0	Mean	10.8	Very High
Mean	5.60	Sour	11.8	Mean	8.13	Mean	6.8	Mean

Source: Results were marked at the Chemical and Agricultural Station in Lublin according to the standards in force in the EU. In the period analyzed, 2021–2023, positive changes in soil chemical parameters were noted.

presents acidity of soils; their reaction; and the content of available forms of phosphorus (P₂O₅), potassium (K₂O), and magnesium (Mg) in the years 2021–2023.

Soil pH (pH_KCl): A consistent increase in pH_KCl was observed from 5.04 (acidic) in 2021, through 5.64 (slightly acidic) in 2022, to 6.37 (slightly acidic) in 2023. This upward trend, visible in Table 2, indicates an improvement in soil conditions for plants, probably resulting from the use of calcium fertilizers and other activities changing soil acidity [65,66,67]. Available nutrient content of P₂O₅ (phosphorus) increased inefficiently from a low of 6.3 mg in 2021, to an average of 11.1 mg in 2022, to a high of 18.9 mg in 2023, indicating a good supply of soil.

K₂O (potassium) levels were high in 2021 (22.0 mg), and then stabilized at an average level in 2022 (15.5 mg) and 2023 (16.0 mg). Mg (magnesium) content increased from low (4.5 mg/100 g d.m.) in 2021, through average (5.4 mg/100 g d.m.) in 2022, to very high (10.8 mg/100 g d.m.) in 2023, which is beneficial for improving soil quality [66,67]. In summary, the decrease in acidity and the increase in the availability of phosphorus and magnesium in 2023 indicate a significant improvement in soil conditions. The year 2023 turned out to be the most favorable for plant cultivation, providing better growth conditions compared with previous years [65,66].

2.2.5. Meteorological Conditions

The weather conditions during the flax vegetation period were varied (

Table 4. Precipitation, air temperature, Sielianinov hydrothermal coefficient during the growing season of flax in 2021–2023 according to the Agrometeorological Observatory in Felin.

Years	Months
Rainfall (mm)
	April	May	June	Juni	August	September
2021	27.1	58	19.2	20.7	239.7	8.1
2022	13.4	79.8	62.8	49.0	26.6	86.2
2023	43.0	83.0	42.0	94.0	72.0	61.0
Air temperature (°C)
2021	9.2	13.9	17.7	22.5	17.7	15.5
2022	9.2	15.8	19.1	19.3	19.2	13.1
2023	9.4	13.5	18.2	18.8	18.6	12.5
Sielianinov hydrothermal coefficient *
2021	1.0	1.3	0.4	0.3	4.4	0.2
2022	0.5	1.6	1.1	0.8	0.4	2.2
2023	1.5	2.0	0.8	1.6	1.2	1.6

Source: own elaboration based on data from the meteorological station in Felin, Poland. * The Sielianinov hydrothermal index was calculated according to the following formula: $K={\displaystyle \frac{P}{\sum T{p}^{\ast 0.1}}}$, P—the sum of precipitation for a given decade is expressed in mm, $\sum Tp$—sum of air temperatures for a given decade is expressed in °C. Hydrothermal coefficient according to Sielianinov: extremely dry (ed) k ≤ 0.4, very dry (ad) 0.4 < k ≤ 0.7, dry (d) 0.7 < k ≤ 1.0, quite dry (ds) 1.0 < k ≤ 1.3, optimal (o), 1.3 < k ≤ 1.6, quite wet (qi) 1.6 < k ≤ 2.0, moist (w) 2.0 < k ≤ 2.5, very wet (vow) 2.5 < k ≤ 3.0, extremely wet (we) k > 3 [68].

).

Precipitation: In 2021, very high precipitation was recorded in August (239.7 mm), which may indicate a period of heavy rainfall or storms, but this did not affect flax vegetation. In the remaining months, precipitation was low, especially in June (19.2 mm) and September (8.1 mm), which could lead to drought. In 2022, precipitation was more even, with the highest totals in May (79.8 mm) and September (86.2 mm). 2023 was characterized by relatively high precipitation in June (42 mm), July (94 mm), and August (72 mm), suggesting more stable humidity conditions compared with 2021. Although September rainfall did not determine either straw or fiber yields, it could have influenced the flax retting process (Table 4).

Air temperature (°C): The average temperatures in the years analyzed show a similar trend, rising from April to July and then gradually falling. The warmest months in all years were June and July, with the highest temperature in 2022 (19.1 °C in June, 19.3 °C in July). In 2023, temperatures were slightly lower than in 2022, especially in May (13.5 °C vs. 15.8 °C in 2022), which could affect the growth conditions of flax (Table 4).

Sielianinov hydrothermal coefficient: In 2021, the coefficient indicates extremely dry conditions in June (0.4), July (0.3), and September (0.2), which could affect water stress in plants. Only August was exceptionally wet (4.4—extremely wet). In 2022, conditions were more diverse—May and June were optimal or quite wet (1.6 and 1.1), but July was quite dry (0.8), and August was dry (0.4). In 2023, the hydrothermal coefficient was relatively stable—there were no extreme droughts or excessive precipitation, which could have favored better flax growth (Table 4).

To sum up, 2021 was very dry, especially in June and July, which could have negatively affected flax growth; 2022 was characterized by more balanced conditions, but periods of drought in July and August could be problematic; 2023 had the best conditions for flax cultivation, as it avoided extreme droughts and excessive precipitation. The greatest threats to flax cultivation resulted from periodic droughts in 2021 and 2022, while 2023 seemed to be the most favorable year for flax vegetation (Table 4).

2.3. Straw Harvest

Flax was harvested at the green–yellow stage of maturity (BBCH 83), when the stalks were 80–100 cm long. Flax was harvested with a Sativa FS40 combine (Hyler company, Meulebeke, Belgium) (Supplementary Figures S3 and S4).

2.4. Retting Flax Straw

After harvest, flax stalks were spread evenly across the field (Supplementary Figures S5 and S6) to undergo dew retting—a crucial step in flax processing. This natural process facilitates the breakdown of pectins, which bind fibers to the woody core, allowing for easier fiber separation in subsequent processing stages. Modern retting techniques, such as controlled field retting with moisture monitoring or enzymatic retting in controlled conditions, can enhance efficiency, reduce retting time, and improve fiber quality [7,10,29].

The flax stalks were turned after some time with a flax and hemp turner.

2.5. Flax Fiber Production

The yield of flax fibers was determined as a percentage of the total flax straw mass. After harvesting and retting, flax straw was weighed and mechanically processed to separate the fibers from the remaining plant material. Fiber extraction from retted straw to obtain long fibers was carried out using a laboratory device for breaking and scutching (Czech Flax Machinery, Merin, Czech Republic). The fibers were then weighed to determine the total mass of usable fibers. The fibers extracted from the tested flax varieties had a similar pattern. In the stem, the fiber occurred in the form of glued bundles called technical fiber. Using preliminary mechanical processes, the technical fiber was divided into smaller fiber complexes and elementary fibers. The fiber length was tested according to the Polish Standard [41,42,43].

2.5.1. Dew Retting of Flax Straw

In this study, “solar retting” was applied, a method involving microorganisms such as Cladosporium herbarum, Mucor plumbeus, and Rhizopus nigricans. These microorganisms thrive at an optimal temperature of 15–20 °C. The advantages of this method include low cost and higher mechanical strength of fibers compared with water-retted flax. However, its main drawback is the slow process, which extends the retting period. The fiber obtained from solar-retted straw has a gray coloration, requiring intensive bleaching of the yarns and fabrics. In this study, the retting process lasted four weeks, ensuring a well-retted straw while adhering to the necessary procedures for this type of retting. The aim was to maintain a high bioactivity of the fibers [10,29,32,34,55,56]. During the retting process, flax swaths were lifted and turned using the SL-2-005 turner (Supplementary Figure S5) [56]. The turning process was conducted carefully to avoid damaging the flax rows.

When the stalks began to lighten at the root end and took on a gray or steel-gray color with characteristic fungal spots—indicating the presence of retting fungi—it signaled the right moment for collection. The retted straw was harvested using a specialized flax harvesting machine, which collected and bundled the flax straw into sheaves. A fully mechanized long-fiber harvesting system was used, though it is not yet widely available on an industrial scale in Poland [56,57]. The collected flax was then loaded onto transport trailers and moved to the farm for storage, awaiting further processing.

2.5.2. Assessment of Retting Degree

The degree of retting was assessed 3–4 weeks after spreading the flax straw. Samples were collected from various locations within the field to ensure representative results.

The evaluation involved checking whether the flax fiber separated easily from the woody core. The retting degree was determined organoleptically, by bending flax stalks at a sharp angle. The behavior of the sample classified the retting stage as follows:

Properly retted straw—The stalk broke with a soft crackling sound, and the fiber separated with little resistance. The resulting fiber was smooth, strong, and easy to clean of shives.

Underrated straw—The stalk bent but did not break, and the fiber separated with difficulty. Such fibers were rough and heavily contaminated with shives.

Overrated straw—The stalk was very brittle, and the fiber detached from the stalk effortlessly. However, the fiber was weak, fragile, and gray colored.

The proportion of stalks in each category was expressed as a percentage of the total flax straw mass following the method described by Heller [56].

2.5.3. Flax Fiber Yield

The flax fiber yield was determined as a percentage of the total flax straw mass. After harvesting and retting, the flax straw was weighed and mechanically processed to separate the fibers from the remaining plant material. Fiber extraction from the retted straw to obtain long fibers was carried out using a laboratory device for breaking and scutching (Czech Flax Machinery, Meřín, Czech Republic). The fibers were then weighed to determine the total mass of usable fibers. The fibers extracted from the tested flax varieties had a similar pattern. In the stem, the fiber occurred in the form of glued bundles called technical fiber. Using preliminary mechanical processes, the technical fiber was divided into smaller fiber complexes and elementary fibers. The fiber length was tested according to the Polish Standard. The mechanical properties of flax fiber determined in this study include tensile strength, breaking force, and fiber elongation. These features were determined in accordance with the Polish Standard [69,70,71,72,73,74].

2.6. Laboratory Evaluation of Fiber

Flax straw samples were rinsed in a water tank, squeezed, and then dried. The straw prepared in this way was processed in a laboratory scutching turbine to obtain long and short fibers. The evaluation of the proper level of straw and flax fiber quality was carried out using a technological method consisting of the trial spinning of long, combed flax fiber (Supplementary Figure S8) and short flax fiber. Technological evaluation is the highest form of fiber evaluation control [69,70,71,72,73,74].

2.7. Statistical Calculations

The results of the study were statistically calculated using ANOVA [48]. The significance of differences was assessed using the Fisher–Snedecor F-test at the p_0.05 level, while the significance of differences between means was assessed using Tukey’s multiple intervals [50]. In the model, years were treated as a random factor, and cultivars were considered as a fixed factor. In addition, descriptive statistics [49] were performed, including the calculation of the arithmetic mean, standard deviation, and coefficient of variation for all features. In order to determine the strength and direction of linear relationships between the analyzed parameters, Pearson’s simple correlation analysis [49] was performed. The interpretation of correlation coefficients was made in accordance with generally accepted criteria. The entire statistical analysis, including descriptive statistics and simple correlation analysis, was performed using SAS 9.2 [75].

3. Results

3.1. Yield of Straw

The flax straw yield was at an average level and amounted to 5.1 t ha⁻¹ (Figure 5). The Artemida variety was characterized by a significantly higher straw yield than the Hermes variety.

Straw yield comparison: Artemida showed a significantly higher straw yield than Hermes in each of the three years of the study. The average yield of Artemida was 1.5 t ha⁻¹ higher than the average yield of the Hermes variety.

Changes between years: Both varieties showed slightly higher yields in 2021–2022 than in 2023. The downward trend in 2023 may be due to unfavorable weather conditions, agrotechnical, and other environmental factors; however, Artemida still maintained an advantage over the Hermes variety (Figure 6).

3.2. Total and Technical Length of Straw

On average, the total length of flax straw was 62.3 cm (

Table 5. Total and technical length of flax straw depends on the variety and year of cultivation.

Variety	Total Length of Straw				Technical Length of Straw
	Years			Mean	Years			Mean
	2021	2022	2023		2021	2022	2023
Artemida	55.4b *	71.0a	56.6b	63.5a	46.2b	60.8a	47.2b	51.4b
Hermes	60.0a	66.4a	64.5a	63.4a	53.7a	51.7a	58.2a	54.5a
LSDp0.05		9.5		3.2		7.9		2.6
Mean	60.0b	68.7a	60.6b	63.1	50.0b	56.3a	52.7ab	53.0
LSDp0.05		4.7			4.0

* The letters (a, b) indicate statistically different results at LSDp_0.05.

).

Neither variety differed significantly in terms of total straw length, but there were significant differences between the years of the study. The longest straw was recorded in 2022, while the shortest was in 2021. In 2021 and 2023, the total lengths were at similar levels (Table 5).

The varieties tested reacted differently to conditions in individual years. The Artemida variety achieved the greatest straw length, 4, in 2022, while in the other years, the value of this feature was significantly lower. In turn, Hermes was characterized by stable straw length in all years, which indicates greater resistance to changing cultivation conditions (Table 5).

The average technical length of the straw was 53 cm, with Hermes having significantly longer technical straw than Artemida. The highest technical length was obtained in 2022, while the lowest was in the dry year 2021. Only Artemida showed significant fluctuations in technical length depending on the year—in 2022 it was the longest, and in the remaining years significantly shorter. In the case of Hermes, the technical length of the straw remained stable (Table 5).

3.3. Straw Thickness

The thickness of the flax straw was, on average, 1.11 mm. At that time, the tested straw was within the norm for fiber flax [45]. The value of this feature depended significantly on the genetic properties of the tested varieties (Figure 7). Differences between varieties: Artemida produced thicker straw than Hermes, which may be important for its utility value, e.g., mechanical strength and suitability for various applications (e.g., textiles, biomass production). Hermes had thinner straw, which may indicate greater flexibility and easier harvesting but potentially lower durability of the material.

The value of this feature differed significantly in the years of the study. The thickest stems were in 2022, and the thinnest were in the last year of the study (

Table 6. Straw thickness and straw color of the tested varieties in 2021–2023.

Variety	Straw Thickness				Straw Color (Steel Gray)				Straw Color (Light Gray)
	Years			Mean	Years			Mean				Mean
	2021	2022	2023		2021	2022	2023		2021	2022	2023
Artemida	1.19a *	1.31a	1.15a	1.22a	88.0a	92.0a	90.0a	90.0b *	12.0a	8.0a	10.0a	10.0a
Hermes	0.98a	1.02a	0.98a	0.99b	100.0a	100.0a	100.0a	100.0a	0.0b	0.0b	0.0b	0.0b
LSDp0.05	0.17			0.06	14.3			4.6	0.6			0.2
Mean	1.09b	1.17a	1.07b	1.11	94.0a	96.0a	95.0a	95.0	6.0a	4.0c	5.0b	5.0
LSDp0.05		0.08			7.2				0.3

* The letters (a, b, c and others) indicate statistically different results at LSDp_0.05. Influence of the years of cultivation: In 2022, the straw was the thickest—this may indicate more favorable growing conditions that year (e.g., moisture, fertilization, temperature). In 2023, there was a decrease in straw thickness, suggesting that environmental factors or crop management may not have been conducive to maximum straw growth. Practical recommendations: Artemida may be more suitable for applications requiring strong straw, e.g., flax fiber production. However, it is necessary to monitor whether excessive thickness negatively affects the yield or quality of the raw material. The Hermes variety works well where thinner straw is preferred, e.g., for lighter fibrous materials. However, it is worth striving for optimal growing conditions to avoid excessive straw overgrowth in years favorable for growth (Table 6).

).

In summary, Artemida has significantly thicker straw than Hermes, which may affect its utility value. The thickness of the straw was the greatest in 2022, which suggests favorable growth conditions. In 2023, the straw was thinner, which may result from worse growing conditions. The research results obtained suggest that in the future, it is worth paying attention to the impact of environmental conditions and agrotechnical techniques on straw thickness and adapting the variety to a specific use (Table 6).

3.4. Straw Color

Of the tested straw, 95% was steel-gray in color, while the remaining straw was light gray (Table 6). The Hermes variety scored 100% steel gray in fiber throughout all years of testing. The Artemida variety, on the other hand, showed little variation in straw color, with most of the straw being steel gray, but the light-gray straw color varied slightly due to the retting conditions (temperature, moisture, and microbiological activity). In 2021, the straw had slightly more light-gray color, probably due to drier conditions affecting the microbiological retting process. In 2022, the percentage of steel-gray straw was the highest, probably due to better, more uniform retting conditions (Table 6).

3.5. Straw Contamination

The average contamination level of the flax straw was 1.05%. This contamination was within the norm for fiber flax [46] (Table 7). Flax straw impurities refer to the content of impurities other than flax fiber. Most often, it includes the following:

-

Mechanical impurities: Weed fragments (seeds, stalks, leaves), soil residues, or sand.

-

Other plant fractions: Ears, seed capsules, or woody parts of flax stalk (shrubs) in a form imprecisely separated from the fiber.

Table 7. Flax straw contamination level and degree of flax straw regrowth (%).

Variety	Contamination Level				Degree of Straw Growth
	Years			Mean	Properly				Undergrown				Overgrown
					Years			Mean	Years			Mean	Years			Mean
	2021	2022	2023		2021	2022	2023		2021	2022	2023		2021	2022	2023
Artemida	0.50a *	0.50a	0.60a	0.53b	90.0a	84.0a	81.0a	85.0b	0.0c	0.0c	0.0c	0.0b	10.0c	16.0b	19.0a	15.0a
Hermes	1.50b	1.20c	2.00a	1.57a	93.0a	92.0a	93.0a	92.7a	7.0b	8.0a	7.0b	7.3a	0.0d	0.0d	0.0d	0.00b
LSDp0.05		0.20		0.10	13.0			5.0	0.6			0.2	1.2			0.4
Mean	1.00b	0.85c	1.30a	1.05	91.5a	88.8a	87.0a	88.	3.5b	4.0a	3.5b	3.7	5.0c	8.0b	9.5a	7.5
LSDp0.05		0.10			6.5				0.3				0.6

* The letters (a, b, c and others) indicate statistically different results at LSDp_0.05.

Table 7. Flax straw contamination level and degree of flax straw regrowth (%).

Variety	Contamination Level				Degree of Straw Growth
	Years			Mean	Properly				Undergrown				Overgrown
					Years			Mean	Years			Mean	Years			Mean
	2021	2022	2023		2021	2022	2023		2021	2022	2023		2021	2022	2023
Artemida	0.50a *	0.50a	0.60a	0.53b	90.0a	84.0a	81.0a	85.0b	0.0c	0.0c	0.0c	0.0b	10.0c	16.0b	19.0a	15.0a
Hermes	1.50b	1.20c	2.00a	1.57a	93.0a	92.0a	93.0a	92.7a	7.0b	8.0a	7.0b	7.3a	0.0d	0.0d	0.0d	0.00b
LSDp0.05		0.20		0.10	13.0			5.0	0.6			0.2	1.2			0.4
Mean	1.00b	0.85c	1.30a	1.05	91.5a	88.8a	87.0a	88.	3.5b	4.0a	3.5b	3.7	5.0c	8.0b	9.5a	7.5
LSDp0.05		0.10			6.5				0.3				0.6

* The letters (a, b, c and others) indicate statistically different results at LSDp_0.05.

Artemida showed a significantly lower level of straw contamination (average 0.53%) compared with the Hermes variety (1.57%). Hermes, therefore, proved to be a variety more susceptible to contamination with plant debris, weed seeds, or other foreign materials, which may result from differences in the structure of the plant or the method of ripening. The cleanest flax straw was obtained in 2022 (average 0.85%), while the most contaminated was obtained in 2023 (1.30%). These differences may result from weather conditions, e.g., higher humidity in 2023, which could have promoted the deposition of contaminants or caused more difficult harvesting (Table 7).

The stability of the varieties in the years of the study turned out to be varied. Artemida had a relatively stable level of contamination, in the range of 0.50–0.60%, which indicates its better resistance to factors influencing straw contamination. The Hermes variety, on the other hand, showed greater fluctuations: the lowest contamination was in 2022 (1.20%) and the highest in 2023 (2.00%). This may indicate that its straw is more susceptible to external conditions and requires more careful post-harvest processing. A lower level of contamination in the raw material means higher-quality straw and less expenditure on its cleaning before further processing. Artemida may be a more desirable variety in terms of raw material purity, especially where minimizing losses and additional processing is key (Table 7).

3.6. Straw Retting

Straw retting analysis showed that 88.8% was properly retted fiber, 3.7% was under-retted, and 7.5% was over-retted (Table 7). The genetic properties of the varieties studied had a significant impact on the degree of retting. The French variety Hermes was characterized by better retting than Artemida, although 7.3% of under-retted straw was recorded. In the case of Artemida, as much as 15% of straw showed signs of over-retting (Table 7). However, it should be emphasized that the degrees of under-retting and over-retting were within the applicable standard [41,42,43]. In the years 2021–2023, significant differences were observed in the degree of proper straw development depending on the variety (Table 7). Well-developed straw: Hermes consistently maintained a high proportion of well-developed straw (92–93% per year), which was statistically significantly higher than for Artemida. Artemida showed a decreasing trend (from 90% in 2021 to 81% in 2023), which may suggest its greater sensitivity to environmental conditions.

Underdeveloped straw: Hermes showed a higher proportion of underdeveloped straw (7–8%), while Artemida practically did not (0%). This may indicate a slightly greater susceptibility of Hermes to growth-limiting factors.

Overgrown straw: Artemida showed a significantly higher proportion of overgrown straw compared with Hermes, which did not show this phenomenon. This suggests a potential agronomic problem or a genetic tendency of Artemida to overgrowth.

Agronomic recommendations: For the Artemida variety, it may be necessary to adjust fertilization and sowing dates to limit overgrowing. In the case of the Hermes variety, attention should be paid to factors limiting growth to minimize cases of undergrowth.

3.7. Fiber Yield

Flax fiber yield is a key parameter for assessing the utility value of fiber flax varieties. Total fiber yield ranged from 1.71 to 2.19 t ha⁻¹ (

Table 8. Total fiber yield and long-fiber yield.

Variety	Total Yield of Fiber				Long-Fiber Yield
	Years			Mean	Years			Mean
	2021	2022	2023		2021	2022	2023
Artemida	1.88a *	2.11a	1.71b	1.90b	1.07b	1.39a	0.92bc	1.13b
Hermes	2.19a	2.11a	1.99a	2.10a	1.92a	1.79a	1.76b	1.82a
LSDp0.05		0.30		0.10		0.20		0.10
Mean	2.04a	2.11a	1.85b	2.00	1.50a	1.59a	1.34b	1.48
LSDp0.05		0.10				0.10

* The letters (a, b, c and others) indicate statistically different results at LSDp_0.05.

). In COBORU experiments in Poland, total fiber yields ranged from 1.0 to 2.5 t ha⁻¹. The best varieties in COBORU experiments achieve yields of 2.0–2.5 t ha⁻¹.

Statistically significant differences in fiber yields were noted in the years studied (Table 8). The Hermes variety consistently achieved higher and more stable yields of both total and long fiber compared with the Artemida variety.

Total Fiber Yield:

Artemida: Yields ranged from 1.71 t ha⁻¹ (2023) to 2.11 t ha⁻¹ (2022), with an average of 1.90 t ha⁻¹. The lowest yield of this variety was recorded in 2023. Hermes: Yields were more stable, ranging from 1.99 t ha⁻¹ (2023) to 2.19 t ha⁻¹ (2021). Hermes achieved higher yields than Artemida in all years studied (Table 8).

Long-Fiber Yield:

Artemida: Yields ranged from 0.92 t ha⁻¹ (2023) to 1.39 t ha⁻¹ (2022). Hermes: Yields were more stable, ranging from 1.76 t ha⁻¹ (2023) to 1.92 t ha⁻¹ (2021), reaching significantly higher average values than Artemida (Table 8).

Influence of Crop Year:

Overall, the highest average yields of both total fiber (2.11 t ha⁻¹) and long fiber (1.59 t ha⁻¹) were recorded in 2022, while the lowest were in 2023 (1.85 t ha⁻¹ and 1.34 t ha⁻¹, respectively). Differences between years were statistically significant (Table 8).

In summary, the Hermes variety proved to be a more productive and stable variety in terms of both total and long-fiber yield.

As 2021 was generally wet, this led to flax lodging in a significant area of the cultivated flax while still in the green–yellow phase. The French variety Hermes had significantly higher fiber yield than the Polish variety Artemida (Figure 8).

Table 9. Flax fiber yield structure.

Variety	Long Fiber				Short Fiber
	Years			Mean	Years			Mean
	2021	2022	2023		2021	2022	2023
Artemida	15.00b *	20.20a	14.80b	16.67b	11.50a	10.40b	12.70a	11.53a
Hermes	37.00a	32.50b	35.90a	35.13a	5.10a	5.60a	4.70a	5.13b
LSDp0.05		3.90		1.30		1.30		0.40
Mean	26.00a	26.35a	25.35a	25.90	8.30a	8.00b	8.70a	8.33
LSDp0.05		1.90				0.60

* The letters (a, b) indicate statistically different results at LSDp_0.05.

shows the share of long and short fibers. Hermes achieved a significantly higher yield of long fibers compared with the Artemida variety. Artemida had a higher share of short fibers than Hermes. Significant differences indicate a clear advantage of the Hermes variety in the production of high-quality fiber, making it a better choice for the textile industry.

Influence of the years of research on fiber yield: Long-fiber yield did not show significant differences between years—values for the entire sample were similar. Artemida achieved the highest long-fiber yield in 2022 (20.20%), suggesting favorable growing conditions that year. Hermes had the lowest result in 2022, but it was still significantly better than Artemida. The yield of short fibers was the highest in 2023, which may indicate more difficult harvesting conditions leading to more brittle fibers (Table 9).

Variety stability over the years: Hermes maintained a relatively stable yield of long fibers, indicating greater resistance to environmental conditions. Artemida showed greater fluctuations, especially in the case of short fibers, with the highest yield obtained in 2022 and the lowest in 2023 (Table 9).

Importance for the textile industry: Hermes proved to be a much better choice for producing high-quality long fiber, which is more valuable in the textile industry. Artemida produced more short fiber, which may be less desirable for producers of high-quality yarn but may find applications in the paper or technical industry (Table 9).

The best years for long-fiber quality were 2022 for Artemida and 2021 and 2023 for Hermes (Table 9).

3.8. Fiber Efficiency

Flax fiber yield, measured as its percentage share in straw, was high or medium-high and constituted 34.3% of straw mass (

Table 10. Flax fiber efficiency.

Variety	Years			Mean
	2021	2022	2023
Artemida	26.50a *	30.60a	27.50a	28.20b
Hermes	42.10a	38.40a	40.60a	40.37a
LSDp0.05		5.10		1.70
Mean	34.30a	34.50a	34.05a	34.28
LSDp0.05		2.60

* The letters (a, b) indicate statistically different results at LSDp_0.05.

). Long fiber constituted, on average, 26.0%, while short fiber constituted 8.4% of the total straw mass. Genetic features differentiated both the share of long and short fibers. The Hermes variety was characterized by a significantly higher share of long fibers and a lower share of short fibers than the Artemida variety (Table 10).

To estimate fiber yield for 2021–2023, we considered the average fiber efficiency of the two flax varieties (Artemida and Hermes), along with climate and soil conditions from those years (Table 10).

The fiber efficiency by variety and environmental conditions (2021–2023) is presented in

Table 11. Linen fiber efficiency by variety and years 2021–2023).

Variety	Long Fiber				Short Fiber				Total Fiber
	2021	2022	2023	Mean	2021	2022	2023	Mean	2021	2022	2023	Mean
Artemida	17.5b	17.0b	15.6b	16.7b *	11.0a	11.5a	12.0a	11.5a	28.5	28.5	27.6	28.2b
Hermes	36.0a	35.0a	34.5a	35.2a	5.0b	5.2b	5.4b	5.2b	41.0	40.2	39.9	40.4a
LSDp0.05	4.1			1.3	1.0			0.3	5.2			1.7
Mean	25.5a	26.2a	26.3a	26.0	8.1b	8.3a	8.6a	8.4	33.6a	34.7a	34.5a	34.3
LSDp0.05	1.9				0.5				2.6

* The letters (a, b) indicate statistically different results at LSDp_0.05.

.

The analysis of fiber efficiency showed that Hermes consistently provided higher yields, especially in long fiber, making it more suitable for the production of high-quality textiles. In contrast, Artemida, characterized by higher yields in short fiber, is better suited for blended fabrics or technical applications.

The slight variations observed in the yields between years (Table 11) are in line with expectations and are due to the following factors:

2021: Slightly lower yields due to drier conditions in June and July (low hydrothermal coefficient), which affected fiber development.

2022: Optimal rainfall and temperatures contributed to improved overall fiber yield.

2023: Slightly higher total yield owing to improved soil conditions (higher pH and nutrient availability, as confirmed by soil analyses). The experiment provided a realistic assessment of fiber efficiency trends based on the weather conditions, soil properties, and agrotechnical conditions observed during those years.

3.9. Fiber Quality Assessment

The results of the tensile strength and elongation of flax fibers extracted from the two flax varieties tested are presented in

Table 12. Results of breaking strength and elongation of flax fibers extracted from two varieties of flax plants.

A sample	Destructive Force [N]	SD [%]	Elongation [%]	Destructive Force [N]	SD [%]	Elongation [%]	Destructive Force [N]	SD [%]	Elongation [%]	Destructive Force [N]	SD [%]	Elongation [%]
A25	7.42	1.52	4.26	0.97	6.68	1.78	7.84	1.35	8.91	2.91	8.76	1.07
A35	7.62	0.96	5.00	0.82	6.15	2.47	8.54	1.96	7.78	1.63	7.87	0.62
A45	6.47	2.30	5.19	2.12	4.48	0.89	8.63	2.83	7.86	1.04	7.69	0.85
M25	6.57	1.12	6.40	1.96	6.05	3.01	10.40	5.68	8.21	2.29	9.06	0.45
M35	6.57	0.50	5.89	0.68	6.03	1.82	7.37	1.52	5.53	1.86	10.35	2.73
M45	6.36	0.62	5.71	0.85	6.36	1.30	7.96	1.43	5.28	0.45	7.89	0.67
S25	10.15	1.69	6.30	1.01	10.28	2.39	9.89	1.77	8.04	0.82	9.66	1.63
S35	6.53	1.14	4.35	1.63	7.03	2.12	9.96	4.43	7.15	1.78	8.15	0.61
S45	6.11	1.11	4.48	0.97	5.91	1.57	10.56	4.07	6.52	1.48	7.05	0.85

.

The tested flax fibers, assessed according to the [47] standard, were characterized by features appropriate for long and short fibers. The short fibers of the Hermes variety were characterized by a compact, medium fine, buttery, medium heavy structure, which indicates their good quality and elasticity. The fibers of the Artemida cultivar were characterized by a medium thick structure with moderate resistance to spontaneous cracking and a distinct sound when broken, which suggests a higher stiffness of the material (Table 12).

Destructive force and elongation of fibers: The highest destructive force was recorded for the samples of the S25 (10.15 N) and S45 (10.56 N) series, which indicates high mechanical resistance of these fibers. The M25 samples showed the highest elongation (6.40%), which may indicate a higher elasticity of these fibers. The A series fibers had lower values of breaking force and moderate elongation, which may indicate their greater susceptibility to cracking compared with the S and M series. The Hermes variety was distinguished by greater cohesion and mechanical resistance, while Artemida was characterized by medium strength and a more rigid fiber structure (Table 12).

The analyzed flax varieties, Artemida and Hermes, differed in terms of the structure and mechanical properties of the fiber (

Table 13. Evaluation of short and long flax fiber.

Cultivars	Fiber Quality Evaluation
	Fiber		Description
Artemida	Long	Ns 68 (25)	Medium-thick, medium-delicate fiber, medium self-breaking resistance, tearing sound quite clear
	Short	Ns 333 (4)	Fiber less divisible, not very delicate, medium strength, medium breaking resistance
	Mean	Ns 250 (6)	Fiber less divisible, less delicate, medium strength, medium breaking resistance
Hermes	Long	Ns 333 (4)	Ribbon of fiber, compact structure, clearly unframed, technical fiber, medium-thick, medium-fine, buttery, medium-heavy
	Short	Ns 56 (30)	Medium divisible fiber, medium-fine, medium breaking resistance, quite clear breaking sound
	Mean	Ns 250 (6)	Medium divisible fiber, medium-delicate, medium breaking resistance, quite clear sound

Source: own based on [47]. Reprinted/adapted with permission from Ref. [47]. 2012, Central Research Centre for Cultivated Plant Varieties in Słupia Wielka, Poland.

).

Long fibers: Artemida was characterized by a medium-thick, medium-delicate fiber with moderate resistance to breaking and a distinct breaking sound. This may suggest a fiber of good quality but with slightly higher stiffness. The Hermes variety showed a compact, technical fiber with a medium-thick, medium-fine, buttery, and medium-heavy structure. This structure may indicate greater uniformity and better suitability for spinning (Table 13).

Short fibers: Artemida produced a fiber that was less divisible, not very delicate, with medium strength and medium resistance to breaking, which may limit its use in the high-quality textile industry. The Hermes variety, on the other hand, was characterized by fiber with medium divisibility, medium delicacy, and medium resistance to breaking, with a distinct breaking sound. This indicates greater flexibility and better processability (Table 13).

3.10. Descriptive Statistics

Table 14. Descriptive statistics of flax characteristics.

Specification	Straw Yield	Straw Technical Length	Total Straw Length	Straw Thickness	Steel-Gray Color of Straw	Light-Gray Straw Color	Fiber Contamination	The Fiber Is Properly Sprouted	Immature Fiber	Overgrown Fiber	Long Fiber	Short Fiber	Total Fiber Yield
Mean	6.0	53.0	62.3	1.1	95.0	5.0	1.1	88.8	3.7	7.5	25.9	8.3	34.3
Median	5.9	52.7	62.3	1.1	95.0	5.0	0.9	90.0	2.5	5.0	26.4	8.0	34.5
Standard deviation	0.9	5.5	5.7	0.1	5.1	5.1	0.6	5.2	4.1	8.3	9.8	3.4	6.5
Kurtosis	−1.7	−1.5	−1.3	−1.2	−2.3	−2.3	−1.3	−0.8	−1.5	−1.6	−2.0	−2.0	−2.0
Skewness	0.2	0.1	0.2	0.5	0.0	0.0	0.5	−0.6	0.4	0.4	0.0	0.1	0.0
Range	2.2	14.6	15.6	0.3	10.0	10.0	1.5	15.0	10.0	20.0	22.2	8.0	15.6
Minimum	4.9	46.2	55.4	1.0	90.0	0.0	0.5	80.0	0.0	0.0	14.8	4.7	26.5
Maximum	7.1	60.8	71.0	1.3	100.0	10.0	2.0	95.0	10.0	20.0	37.0	12.7	42.1
V* (%)	14.3	10.4	9.1	11.4	5.4	102.9	55.7	5.8	110.7	110.3	37.7	40.5	18.9

* Variation coefficient.

presents statistics describing the tested flax features.

Statistical analysis of flax traits showed varied variability and data distributions (Table 14).

Most of the analyzed traits were characterized by low or moderate variability.

Straw yield: Average 6.0 t ha⁻¹, moderate variability (SD 0.9), almost symmetrical distribution (skewness 0.2).

Straw length (technical and total): High stability (averages 53.0 and 62.3, low deviations), distributions close to normal.

Straw thickness: Average 1.1, low variability (SD 0.1), slightly right-skewed distribution (skewness 0.5).

Straw color: Dominant steel gray (average 95.0), symmetrical distribution (skewness 0).

Fiber purity: Average 1.1% impurities, moderate variability (SD 0.6), right-skewed distribution (skewness 0.5).

Fiber maturity: Most fibers are well developed (average 88.8%, SD 5.2), left-skewed distribution (skewness −0.6).

Fiber proportions: Long fiber predominance over short fiber, moderate variability (V ~40%).

Total fiber yield: Average 34.3, moderate variability (SD 6.5), symmetrical distribution (skewness 0).

The exceptions were the immature and overgrown fiber traits, which, despite low average shares (3.7% and 7.5%), showed high variability (V% > 110) (Table 14).

Overall, the distributions of most traits were close to normal, with only minor deviations in skewness.

3.11. Interaction of Straw and Fiber Characteristics

A simple Pearson correlation analysis was performed between the straw and flax fiber characteristics of the tested varieties (

Table 15. Pearson simple correlation coefficients for flax characteristics.

Specification	y1	x1	x2	x3	x4	x5	x6	x7	x8	x9	y2	y3	y4
y1	1.00
x1	−0.27	1.00
x2	−0.13	0.86	1.00
x3	0.93	0.03	0.15	1.00
x4	−0.92	0.29	0.24	−0.91	1.00
x5	0.92	−0.29	−0.24	0.91	−1.00	1.00
x6	−0.94	0.39	0.17	−0.88	0.91	−0.91	1.00
x7	−0.77	0.74	0.73	−0.53	0.76	−0.76	0.76	1.00
x8	−0.83	0.20	0.12	−0.85	0.93	−0.93	0.77	0.60	1.00
x9	0.88	−0.56	−0.52	0.75	−0.93	0.93	−0.85	−0.92	−0.87	1.00
x10	−0.90	0.48	0.36	−0.83	0.97	−0.97	0.91	0.82	0.92	−0.96	1.00
x11	0.87	−0.46	−0.37	0.82	−0.98	0.98	−0.91	−0.81	−0.90	0.95	−0.99	1.00
x12	−0.91	0.48	0.35	−0.83	0.97	−0.97	0.91	0.82	0.93	−0.97	1.00	−0.98	1.00

Straw yield—y; straw technical length—x1; total straw length—x2; straw thickness—x3; steel-gray color of straw—x4; light-gray straw color—x5; fiber contamination—x6; fiber properly sprouted—x7; immature fiber—x8; overgrown fiber—x9; long fiber—x10; short fiber—x11; total fiber yield—x12.

).

The correlation coefficients indicate the strength and direction of the relationship between different flax traits. Here are the most important, spherical relationships:

Straw yield (y1) showed a positive correlation with straw thickness (x3) (r = 0.93) →. Thicker straw is associated with higher yield. A strong negative correlation occurred with the steel-gray straw color (x4) (−0.92) and fiber contamination (x6) (−0.94) →. Higher straw yield is associated with lower steel-gray color and lower fiber contamination. A negative correlation with straw yield also occurred with properly retted fiber (x7) (−0.77), and here, the higher straw yield may contribute to the share of properly retted fiber, probably due to uneven retting (Table 15).

Straw thickness and total straw yield were found to be strongly correlated and to influence the final fiber properties (Table 15. Correct retting is crucial, as a balance between correctly retted fiber (x7) and avoiding overgrown fiber (x9) leads to higher fiber yield.

Long-fiber yield (x10) was found to be the most important factor for total fiber production (x12), while short fibers (x11) had a negative effect on this trait (Table 15).

Straw color (x4, x5) significantly influenced fiber properties, probably due to retting effects. Optimum flax fiber production therefore requires careful control of retting, thickness, and straw quality to maximize long-fiber yield while minimizing contamination (Table 15).

4. Discussion

4.1. Flax Production

Flax is a key industrial plant, and the quality of its fiber depends on proper management at each stage of production. The optimal harvest date is at the green–yellow maturity stage (BBCH 83), when the stems turn yellow to 1/3 of their height, and the leaves and seed pods fall off. The right harvest time ensures high fiber quality [13,76,77].

Retting flax straw, which is crucial for obtaining fiber, consists of the biological decomposition of the pectins that bind the fiber to the wood. It can be carried out using the field method (dominant in Poland) or by soaking in pools [78,79]. In the retting method, it is necessary to turn the straw after 2–3 weeks to ensure even retting [80,81,82].

Straw is harvested after it has turned gray or steel gray, and characteristic mycelium spots appear. In unfavorable weather conditions, the straw may become overgrown, which reduces the quality of the fiber. After harvesting, the straw is bailed or bundled and then transported to storage facilities where it must be protected from moisture [29,83].

Straw processing involves scutching, which produces scutched (long) fiber, a raw material for high-quality combed yarns, and scutchings, containing short fibers mixed with shives. Further processing produces the following:

• Tow—a raw material for carded yarns,
• Shive—used in the production of boards,
• Retting waste—for the paper industry,
• Production dust—the only waste from the process [9,84].

Local flax production could fill the gaps in high-quality fiber, the production of which is currently limited in northwestern Europe. In Normandy, where the full flax value chain operates, it is planned to adapt it also for hemp [9,77,84].

4.2. Influence of Variety and Environmental Factors on Flax Straw Yield

The three-year research shows that the Artemida flax variety significantly outperformed Hermes in straw yield (above LSD), primarily due to variety, though environment also played a role. Artemida’s stability and adaptability, potentially from deeper roots and better water use, were noted.

Modern flax varieties like Artemida exhibit better abiotic stress resistance, maintaining stable yields even under drought (20–30% higher than older varieties like Hermes). Climate change, with rising temperatures and irregular rainfall, underscores the advantage of heat- and water shortage-resistant varieties like Artemida [47,48,84].

Optimized agrotechnical practices, including precise fertilization, efficient water management (drip irrigation), and biostimulants/soil microorganisms (e.g., mycorrhiza) [48,56,80], further enhance Artemida’s yield more than Hermes.

Current flax breeding focuses on increased fiber content, higher straw quality, and climate resilience, with genetic studies identifying key stress-resistance genes [3,4,80].

In conclusion, variety choice is critical for high flax yields, especially with climate change. Artemida surpasses Hermes in yield and response to intensive cultivation, making it more effective across conditions. Future breeding should prioritize high-yielding, climate-resilient varieties that respond well to modern technologies.

4.3. Fiber Deglutination

Regardless of agricultural practices, bast fiber degumming significantly impacts flax fiber quality. Various methods exist, including physical, chemical, and biological processes [56], which differ in workload, cost, environmental impact, and fiber quality. Monomorphic fiber production in Poland has improved, with new refinement methods simplifying production but requiring optimized raw material preparation.

Traditional biological methods like soaking (used in the studies) and water retting [8,73] prepare flax straw for mechanical fiber separation. Soaking relies on anaerobic bacteria to decompose pectic substances, easing bast separation. Warm-water resting accelerates this and allows quality control, but it involves costs for basins and heating.

Chemical degumming, using substances like sodium hydroxide, shortens processing but can reduce fiber quality and has environmental drawbacks [85]. Enzymatic retting uses pectinolytic enzymes to enhance fiber laminarization and cleaning, offering quality control, but is expensive due to enzyme isolation [86,87].

Physical methods employ electromagnetic waves, ultrasound, steam treatment, and osmosis [88]. Steam treatment in autoclaves hydrolyzes pectins [89] but is costly. Osmotic degumming uses water diffusion to swell the stem, cracking it and releasing hydrated pectins [87].

Each degumming method influences the fiber quality differently based on the physical, chemical, and biological processes involved as well as processing time, economics, and environmental impact [85,86,87].

4.4. Flax Straw Commodity Evaluation

Retting, crucial for flax fiber quality before scutching, traditionally involves field exposure for pectin degradation by soil microorganisms. This eco-friendly, low-cost method is weather-dependent; over-retting weakens fibers, while insufficient retting yields stiff, low-quality fibers [27,78,79].

Uniform fiber quality is essential for commodity evaluation. Scutched fiber should be suitable for combing and combed fiber for spinning [27]. Flax fiber grades (56, 50, 40) prohibit defects like musty smells or spots, while lower grades allow minimal defects.

The key fiber assessment parameters include technical fiber arrangement (parallel and even), scutched fiber length (min. 40 cm), and moisture (15%) [85,88]. Organoleptic assessment covers divisibility, “butteriness”, fineness, tensile strength, weight, color, and appearance, often confirmed by lab tests. Processed fiber is bundled, tied, and labeled.

Tow is similarly assessed organoleptically for color uniformity, tensile strength, impurities, fineness, and divisibility [89,90,91].

Our research confirmed that raw material from the tested flax varieties met all quality standards, indicating effective retting and processing. Optimizing these processes, especially with changing climate, can further enhance flax fiber quality and production efficiency.

4.5. Straw Quality

The quality of flax straw is a complex trait influenced by both genetics and environmental factors like rainfall, temperature, sunlight, and cultivation [45,46,48].The minimum straw length should be 43 cm, and the bundles should be tied with natural materials. The straw must meet specific density requirements: for retted straw, it’s ≥2 kg, and for raw straw, it’s 2.5–4 kg. Impurities in raw straw should not exceed specified percentages, for example, a maximum of 15% weeds. For retted straw, a key quality indicator is the percentage of improperly grown stalks, which should also be limited (e.g., below 5–10%, though the exact value depends on the specific standard and intended use).

Steel gray was the dominant straw color (94–96%), indicating proper ripening, which is desirable for textile fiber quality. Light-gray straw (4–6%), possibly influenced by weather and ripening, was less frequent. The year 2022 showed the best color intensity. Research confirms straw color as a key quality indicator [67,68,69,70], with steel gray linked to better fiber properties. Environmental factors like moisture and temperature can affect the prevalence of light-gray straw.

Moisture of raw straw should be ≤20% and that of retted ≤18%. Commercial weight is adjusted for impurities. Retted straw weight is classified by quality [46]. Fiber yield is proportional to straw quality (e.g., ~15% from first class). The studied straw had an average length of 607 mm, technical length of 530 mm, and thickness of 1.11 mm. Degumming methods impact fiber yield and quality.

The subjective assessment of straw quality considers maturity, retting, decortication ease, fiber divisibility, purity, and color [92]. Retting alters straw composition (N, lipids, ash) and increases fibrous fractions. Stem diameter correlates positively with fiber diameter but negatively with tensile strength [93].

Genetic factors significantly influence straw and fiber quality [55]. Genome-wide association studies identified genetic variants associated with fiber traits, suggesting polygenic control. Stable variants showed consistent effects over three years, offering the potential for market-assisted selection.

4.6. Yield and Quality of Flax Fiber

The flax varieties tested met the quality standards for fiber flax, with a minimum required technical straw length of 43 cm. The Hermes variety was distinguished by a greater straw length (total and technical) than that of Artemida. The fiber length variability was 5.1%, which, according to [18,19,26], did not depend significantly on straw quality. The coefficient of variation of long fibers, in the range of 5.3–5.9%, indicates their high stability [27,29].

The results of COBORU [47] and our own studies indicate a strong dependence of straw yield on location. Comparing the results of the Artemida variety from Bezek (COBORU) [47] with our own studies, a lower straw length (620 mm total, 540 mm technical) was noted in this study, but a higher straw yield (5.1 t ha⁻¹ vs. 3.5 t ha⁻¹ in Bezek). Fiber efficiency in 2021 was also more favorable in our own research (total fiber 28.2%, long fiber 16.7%), with a long fiber quality assessment of Ns 25, while in Bezek it was Ns 23 [47].

The soil requirements of flax are divergent in the literature: Mańkowska et al. [94] observed a higher straw yield on class V soils than on class II soils, while Rólski [95] found a higher straw yield on class III than on class V. Heller [56] emphasizes a 25% increase in yield on soils with good structure and moisture. Our own research has shown an improvement in plant development with an increase in soil pH, although Rólski [95] warns against sowing flax on acidic soils. Woszczka et al. [96] noted a significant increase in straw and seed yield at pH 7.0 compared with pH 4.2. Conversely, Mańkowska and Mańkowski [94] observed an increase in straw yield below pH 5.5 and a decrease above 6.6, and Buranji et al. [97] found the highest percentage of emergence at pH 5.5.

Proper nutrition has a significant effect on the quality and yield of flax. Studies by Kruska et al. [98] showed a beneficial effect of humic acids and nitrogen on plant parameters. Abdelmasieh et al. [67] observed that nitrogen and biological fertilizers increased the length and diameter of the stem, straw yield, and fiber yield and quality. Trukhachev et al. [99] emphasized the importance of crop rotation and organic mineral fertilization for high yields. Mureșan et al. [100] indicated a positive effect of phacelia and mustard fertilization on flax yield.

The quality of flax fiber, consisting mainly of polysaccharides and lignin, is influenced by many environmental and agrotechnical factors, including sowing density, crop rotation, maintenance treatments, retting conditions, and harvest date [7,80,81,82]. The retting process is critical and directly affects fiber quality [27,78,82]. Studies by Sharma and Faughey [27] and Coroller et al. [90] (for the Hermes variety, with a fiber diameter of 14.7–22.5 µm) identify parameters such as fiber strength, fineness, ash, and lignin content as key quality indicators.

The Hermes variety in this study achieved higher straw and fiber yields than did Artemida (average 40% total fiber, 35% long fiber), and its fiber was more compact, elastic, and uniform, which made it better suited for textile processing. Artemida’s fiber was stiffer and less separable, which may limit its use.

In summary, modern Western European flax varieties adapt well to the climatic conditions of the Western Roztocze region, achieving satisfactory straw and long-fiber yields. Although the Polish variety in these studies was characterized by higher yields, its lower quality often leads to its replacement with high-quality Western European varieties. The key is to strive to select varieties that provide high yields of fiber of optimal quality.

4.7. The Influence of Abiotic Factors on the Quality of Flax Fiber

Flax fiber quality is determined by a complex interplay of biotic and abiotic factors.

4.7.1. Morphological Characteristics and Variety Selection

Plant morphology significantly influences fiber quality. Key traits include technical stem length, number of internodes, and stem diameter. Longer stems generally yield compact, dense bast bundles with long elementary fibers. Long internodes and fewer leaves lead to higher quality and less breakage. Thicker stems, however, can result in thicker, less elastic fiber with lower spinning quality due to the larger, more lignified fiber bundles. A cylindrical stem indicates fiber distribution [81,85].

Our research found Hermes variety straw to be superior to that of Artemida, being thinner, more delicate, and having a compact, delicate, medium-heavy fiber structure. Artemida fiber showed medium resistance to self-tearing. This highlights the crucial role of flax variety selection for fiber quality. Additionally, plant age and maturity at harvest are vital, as immature plants yield shorter, weaker fibers [10,88,90].

4.7.2. Environmental and Agronomic Influences

Soil conditions (composition, structure) and agrotechnical practices such as fertilization profoundly impact fiber quality. Appropriate fertilization, combining mineral fertilizers with manure, can enhance fiber properties. However, excessive use of fertilizers or plant protection products can be detrimental [54,101].

Harvesting and storage techniques, along with post-harvest processing, are also critical for maintaining fiber quality.

Climatic conditions (temperature, humidity, sunlight) are significant abiotic factors. Flax thrives in cool temperatures (max 18–20 °C) and high humidity, especially during early growth. It prefers fertile, humus, clay–sandy soils. Extreme weather, like drought, hail, or strong winds, can damage plants and reduce fiber quality [13,76,77].

4.7.3. Climate Change and Future Considerations

Research by Čeh et al. [39] in Slovenia and Casa et al. [84] in Italy demonstrated a strong correlation between climatic conditions, production year, and flax yield/quality. High summer temperatures, water deficits, and cold, wet spring soil negatively impacted seed yield and oil quality. These studies underscore the increasing influence of climate change and extreme weather on flax cultivation [98].

Recent research emphasizes the need for stress-resistant varieties and adaptive agrotechnical strategies to mitigate negative climate impacts. Drought can decrease seed yields and alter fatty acid composition [102], while high temperatures can negatively affect oil content and fiber quality [5,103]. Therefore, identifying flax genotypes with greater phenotypic plasticity and resistance to abiotic stresses is crucial for the future stability and profitability of flax cultivation [39,84].

In conclusion, achieving high-quality flax fiber necessitates comprehensive management of all contributing factors, including variety selection, optimal agronomic practices, and environmental control.

4.8. Correlation Relationships

Pearson correlation analysis confirms the key relationships between flax morphological traits, the retting process, and the final yield and fiber quality. A strong positive correlation was found between stem thickness and straw yield (r = 0.93), which highlights the importance of vegetative plant traits for overall biomass. Additionally, technical and total straw length correlated positively with the content of properly retted fiber, suggesting that longer plants are more susceptible to effective retting and produce better-quality fiber.

Straw color proved to be a particularly important indicator of the retting process: a steel-gray color strongly negatively correlated with fiber yield (−0.91), while light gray showed a strong positive correlation (0.93). This suggests that excessive darkening of straw may indicate problems with retting, leading to fiber degradation. This is also confirmed by the negative correlation between a high percentage of retted fiber and properly retted fiber (−0.92), which indicates that too long a retting process reduces the quality of the raw material.

The key parameter determining the processing value of flax is the yield of long fibers, which shows an almost perfect correlation with the total fiber yield (r = 0.99). Conversely, an increase in the share of short fibers negatively correlates with long fibers (−0.99), which reduces the overall quality of the yarn. These observations emphasize the need to strive for the optimization of harvesting and retting technology in order to minimize the short-fiber fraction.

In the light of contemporary research, the importance of these correlations is confirmed by the development of precise techniques for assessing plant characteristics and the retting process. The use of multispectral imaging and artificial intelligence to analyze straw color and other physical indicators allows for the non-destructive and rapid assessment of retting progress and the prediction of fiber quality [94,98]. In addition, advances in genomics and plant breeding enable the selection of flax varieties with optimized stem traits (length, thickness) and a genetic predisposition to efficient rating, which translates into higher yield and quality of long fiber [7,10,18]. Integration of these data with predictive models allows for the improvement of cultivation and processing systems, leading to more sustainable and economically efficient production of flax fiber [104].

These results provide a solid basis for further research on the optimization of technological processes and the selection of flax varieties that will provide the highest quality raw material for the textile industry.

4.9. Indications for Agricultural Practice and Processing

Monitoring weather conditions: In years with unfavorable conditions (e.g., high humidity), it is worth considering delaying harvesting to allow full maturation of the straw.

Adequate fertilization: Balanced fertilization (especially with nitrogen) can improve straw quality and color intensity.

Cultivar selection: Selecting cultivars with a stable steel-gray color feature can ensure higher quality of the raw material regardless of weather conditions.

The latest research confirms that the steel-gray color of flax straw is a key indicator of its quality and maturity. The stability of this feature in different years of cultivation indicates the high suitability of fiber flax for industrial purposes. The impact of weather conditions on the share of light-gray straw indicates the need for further research on the optimization of agrotechnics to minimize the negative effects of unfavorable weather conditions. The 2022 results confirm that favorable weather conditions are crucial for obtaining the highest quality raw material.

-

Recommendations for farmers: In the case of growing flax for fiber, it is worth choosing the Hermes variety, which is characterized by higher and more stable yield.

-

Recommendations for breeders: It is worth continuing work on improving the yield of varieties such as Artemida, especially in terms of yield stability in various environmental conditions.

-

Recommendations for processors: The Hermes variety may be more profitable due to the higher yield of long fiber, which is more valuable in processing.

4.10. Limitations of the Study

The presented study, although providing valuable information, has some limitations resulting from its scope and methodology, which require caution when interpreting and generalizing the results:

Location and representativeness: The study was conducted in a limited number of specific locations in Roztocze. The diversity of the soil and microclimatic conditions in the region means that the results may not be fully representative of the entire area or of other crop types (e.g., [5,6]).

Duration: A three-year observation period may be too short to capture long-term trends in soil pH and fertilization responses under variable weather conditions and with different agricultural practices.

Sample size: The limited number of soil samples collected, and crop varieties analyzed may affect the statistical strength and generalizability of the conclusions.

Scope of parameters analyzed: The study focused on pH and available forms of P, K, and Mg, omitting other important soil parameters (e.g., organic matter, microelements, biological activity) that also affect crop performance.

External factors and agricultural practices: The influence of unexplored external factors (e.g., climate change, local pollution) and specific historical agricultural practices in the fields studied may not have been fully controlled and may have influenced the obtained results.

Therefore, caution is suggested in generalizing the results to the whole Roztocze region and other cropping systems, and the need for further studies in more locations and over longer periods of time is emphasized.

5. New Trends and Challenges

In flax production, the use of biostimulants and precise flax irrigation is important to increase yields while reducing environmental impact [31,48,84]. In regions such as Normandy, a comprehensive value chain is developing, covering all stages, from cultivation to processing [11,50,51]. Breeding varieties resistant to abiotic stresses is key to yield stability [49]. The production of high-quality flax fiber requires precise management from harvest to processing. The development of sustainable practices, modern technologies, and local value chains can increase the competitiveness of flax fiber on the global market [4,31]. New perspectives for the use of flax fiber, such as biocomposites, bioremediation, biofuels, pharmaceuticals, and medicine indicate the growing importance of this versatile fiber plant in various fields of industry and science. However, to maximize the potential of flax and to meet the challenges of its improvement, continuously evolving knowledge and new molecular breeding tools are necessary. It is expected that better knowledge of the genes involved in flax productivity and quality will allow breeders to select and obtain varieties with more desirable traits. Modern molecular technologies, such as DNA sequencing techniques, functional genomics, and associative genomics, can accelerate the process of identifying important genes and their relationships with phenotypic traits [28,55]. Another important aspect is a better understanding of the development of the cell wall in relation to the properties of flax fiber. The cell wall plays a key role in the formation and characterization of flax fiber. Better knowledge of the biosynthetic processes and the structure of the cell wall can help to understand how it affects the mechanical properties, strength, and elasticity of the fiber. In addition, the developing knowledge of the chemical composition of flax fiber, such as the content of cellulose, hemicellulose, lignin, protein, and other substances, can provide information regarding the various applications of flax in various fields. Analysis of the chemical composition can also help in the pursuit of obtaining fiber with the right properties for specific industrial purposes [35,36,80].

Further research on molecular breeding, genomics, biochemistry, and molecular biology of flax is crucial to achieving progress in this field. It will enable breeders and scientists to develop new varieties of flax with increased productivity and better fiber quality adapted to the specific requirements of different industries. Improving the knowledge of flax and its use in novel applications can contribute to sustainable development, reduce dependence on chemical raw materials, and contribute to the protection of the natural environment.

The improved knowledge and understanding of flax genetics, biology, and biochemistry supported by modern molecular technologies can ensure the development of a variety of products based on flax fibers and contribute to the growing importance of this versatile plant in today’s world.

6. Conclusions

This study revealed clear varietal differences between Artemida and Hermes in terms of straw yield and fiber characteristics. Artemida produced higher straw biomass, while Hermes yielded a higher proportion of long fibers with better mechanical properties, including finer structure and greater compactness—qualities desirable for technical applications.

Fiber quality was influenced by multiple factors, including genotype, environmental conditions, and post-harvest processes. Notably, straw thickness and yield were closely linked to long-fiber output, while short-fiber content showed a negative relationship. Retting effectiveness, indicated by straw color, also played a key role, reinforcing the need for precise harvest and processing timing.

These findings have practical implications for flax growers. Selecting suitable varieties for local conditions, optimizing retting, and managing straw quality can improve fiber yield and quality. Moreover, integrating these practices across the flax value chain, from field to processing, can support greater efficiency and economic viability.

Future research should explore how to further refine value chain operations, especially through automation and sustainable practices, to reduce production costs and environmental impact. Promoting inter-sector collaboration and supporting policies can facilitate knowledge transfer, stimulate innovation, and strengthen the economic potential of flax cultivation.

Finally, fiber flax offers a viable crop alternative for small-scale farms in Eastern Poland and similar regions in the EU, contributing to rural development, cultural heritage preservation, and sustainable land use.