Effects of Remote Barley Seed Treatment with Weak Non-Thermal Pulsed Electromagnetic Fields on Plant Development and Yields

Abstract

Numerous scientific studies have confirmed the effectiveness of seed bioactivation using electromagnetic fields (EMFs) in agriculture. This article presents the results of the remote application of an EMF TOR device in the cultivation of barley Hordeum vulgare L. Laboratory studies and field tests were conducted, showing a positive effect on the growth and development of plants both when treating dry seeds before sowing and when treating sown seeds in the field. The optimal time period for EMF treatment was determined: treating air-dried seeds with EMFs before sowing for 10–15 min increased germination by 5–18% and the growth rate of seedlings by 2–3 times. The maximum observed effect occurred during the treatment period from 7:00 to 11:00. As a result of changing the balance of phytohormones, the further stimulation of the root system and the assimilation surface of plants was noted due to a 1.5-fold increase in the content of auxins. The density of productive stems, ear length, seed set, and 1000 seed weight increased, which ultimately led to an increase in yield by more than 10% and, in some varieties, to a decrease in the protein content in grains compared to the control variant (by 3–22%), bringing them closer to brewing conditions.

1. Introduction

Cereals and their derived products are sources rich in carbohydrates, proteins, fats, B vitamins (thiamine, niacin, and riboflavin), vitamin E, and various minerals (calcium, magnesium, potassium, phosphorus, iron, and sodium) [1,2,3]. Their products, such as bread, flour, cereals, etc., provide half of the total caloric content in the daily human diet, due to which cereals are strategically important crops. Modern agriculture is focused on the development and implementation of environmentally friendly technologies; therefore, researchers are trying to develop safe methods for increasing crop yields that do not lead to the contamination of the soil and products through the excessive use of chemical fertilizers. At present, preference is given to technologies that not only have the highest efficiency, but also guarantee safety in terms of environmental overloading.

Physical methods for seed treatment are currently within the scope of scientists’ interest. These include the application of low-temperature plasma [4,5,6], low-dose ionizing radiation and other weak effects on seeds [7,8], short-term heat [9,10] and shock-wave treatment (musical sounding) [11], and laser irradiation [12,13,14,15] during pre-sowing treatment. Physical biostimulation during pre-sowing treatment using magnetic fields is widely recognized for its positive effects on the sowing qualities of pea [16,17], soybean [18], corn [19], cotton [20], and triticale [21] seeds. Pulsed EMFs (PEMFs) improved the vegetative reproduction of oregano [22] and stimulated the germination and yield of soybean seeds [23]. Soybean seed bioactivation using magnetic and electric fields improved germination in all tested varieties [24]. In [25], magnetic fields enhanced the seed quality of different cereals.

Given the positive effects of EMFs on plant growth and development (eustress), researchers have elaborated new EMF emitter types and methods for their application in agricultural practice [26,27,28]. However, obtaining maximum efficiency when applying EMFs depends on various factors, including the EMF intensity and exposure duration, crop type, variety, age, ploidy, and seed morphology [29]. The obtained species-specific reactions observed in different studies suggest that pre-sowing seed treatment using EMFs should be adapted not only to the species and variety, but also to specific seed lots [29,30].

A comparison of the effects obtained on corn seeds exposed to high- and low-intensity magnetic fields, as well as electric and electromagnetic fields for 15 days, showed that the best results were obtained with the EMFs, almost doubling the indicators of interest [31]. Other researchers found that after the pre-sowing EMF treatment (50 Hz) of pea seeds, the germination increased by 2.6%, the sprout length by 5.5%, the root length by 18.6%, and the overall vegetable weight by 6.9% vs. the control [32].

Studies on EMF-sensitive indicators at different periods of plant growth and development have been performed on many agricultural crops [33,34,35]. The susceptibility of plants to high-frequency EMFs has been studied in terms of cellular mechanisms and morphological changes [36]; increases in the germination energy and the growth rate of seedlings [37,38,39,40,41]; improvement in growth processes and cell proliferation [42,43]; increases in the content of photosynthetic pigments and photosystem efficiency; and increases in resistance to unfavorable environmental factors, such as soil and water salinity, soil soaking, and high-intensity ultraviolet light [44,45].

The observed biostimulating effect of magnetic fields on wheat seedlings is explained by the activation of oxidative stress in plants, changes in membrane permeability, and increases in the concentrations of mineral elements in the cells [46]. A study testing different parameters of extremely low-frequency EMFs, including magnetic induction, the treatment duration, and wheat grains harvested in different years, showed that the greatest increase in germination (of 14%) was observed at a treatment duration of 12 min, frequency of 30 Hz, and magnetic induction of 5 mT [47]. Longer exposure (about an hour) reduced grain germination and the seedling size [48]. EMF treatments of triticale seeds can be practiced both in conventional and organic farming to increase the yield [49]. Earlier maturation, in addition to an increased yield, due to EMFs has also been observed in cotton crops [50]. The treatment of sunflower seeds with EMFs and cold plasma caused changes in the balance of phytohormones in the seeds, which led to better seedling development and enhanced protein expression in the plant leaves [51].

Another important area of study focuses on the control of harmful pathogens using EMFs during the growth and storage stages of cereal crop production. The protein, fat, and mineral contents of cereals make them susceptible to microbial contamination both during growth and maturation before harvest and during storage [52]. Secondary toxic metabolites (mycotoxins) of several micromycetes are considered a serious problem [53]. The mycotoxin contamination of crops can occur in fields and during transportation and storage [54]. Non-thermal treatments using alternative simple physical methods, including various types of irradiation, ultrasound, cold plasma, or pulsed electromagnetic fields (PEMFs), are applied to reduce and/or eliminate the contamination of grain surfaces by harmful microorganisms and toxins to improve the safety of grain crops [55,56,57,58]. Treatment is also effective in removing a wide range of bacteria, including genera such as Bacillaceae, Pseudomonadaceae, Actinomycetes, etc., [53].

The above-mentioned references suggest that plant exposure to EMFs can cause various biological effects at the cellular, tissue, and organ levels. During evolution, plants—like all other organisms—have adapted to the existing electromagnetic environment. The intensity and duration of the impact during different development stages can disrupt the plant organism, leading to a variety of reactions.

A comparison of the effects obtained by different researchers shows that the germination results of treated seeds in laboratory in vitro tests may differ from the results obtained when sprouting in vivo in soil. Field observations throughout the entire growing season are required to confirm the observed effects under lab conditions, even those approximating crop growing conditions, and to assess the stability and dynamics of plant responses to EMF seed treatment. In this study, we evaluated the effects of remote electromagnetic seed treatment on barley Hordeum vulgare L. both under lab conditions and in fields.

2. Materials and Methods

This research was carried out in 2023–2024 at the Federal Research Center of Agroecology RAS (Volgograd). Indoor experiments took place in the Laboratory of Breeding, Seed, and Nursery Production; the field experiments were carried out at the Kamyshinskoye Experimental Farm (Kamyshinskiy district, village Gosselektstantsiya).

Experimental fields at the Kamyshinskoye Experimental Farm are located in a dry-steppe zone of typical chestnut soil. The soil is classified as chestnut, medium-moist, heavy loam overlying loess-like loam. According to the data of the local soil diagnostic laboratory data, the prevailing fractions in the mechanical composition are silt (16–28%) and medium sand (37–56%). The humus content in the arable layer contains 2.6–2.8%, with a sharp decrease in the subsoil (30–40 cm) to 2%. The soil solution has a pH of 7.3–7.6, which is close to neutral. The soil density in the half-meter layer varies from 1.26 to 1.61 g/cm³. The absorbed bases in the 0–30 cm layer (in mg eq. per 100 g of soil) are as follows: Ca—20.0; Mg—20.0; and Na—6.0; K—2.25. The gross nutrient content in the 0–30 cm layer is as follows: N—0.2%; P—0.5%; and K—4.9%. In the 30–40 cm layer, these indicators are 0.1, 0.2, and 3%, respectively. The agrochemical analyses of the soil determined the following:

–

The humus content was determined using the method by Tyurin, according to GOST-R 26213-2021.

–

The total nitrogen content was determined using the Kjeldahl method, according to GOST-R 34789-2021.

–

The pH was determined using potentiometry in a 1 n KCl extract, according to GOST-R 26483-2021.

–

The nitrate nitrogen content was determined using aluminum–potassium alum extraction and an I-500 ionometer with an ion-selective electrode, according to GOST-R 26951-2021.

–

The mobile phosphorus and exchangeable potassium content were determined using Machigin’s 1% carbon–ammonium fume hood, according to GOST-R 26205-91.

–

The sum of exchangeable bases was determined using the Kappen–Hilkovitz method, according to GOST-R 27821-2020.

The climate of the test region is sharply continental, winters are cold and snowy, and summers are hot and dry. A characteristic feature of the climate is the presence of strong eastern and southeastern winds and dry winds. In 2023, April and May were dry. The weather was hot and clear in June. Brief showers occurred in the first ten days. There were 12 dry days with air humidity below 30%. The maximum air temperature reached 36 °C. In July, the heat intensified and precipitation was minimal. The highest temperature reached 40 °C in the first ten days of July. A two-week period of drought occurred, with high temperatures, low humidity, and intensive southeast winds.

Plants consumed the productive moisture reserves during the second half of the vegetation period, and drew moisture from developing generative organs, which led to stem pinching, negatively affecting the yield. In August, the air temperature was below the average annual value. Precipitation was minimal until the end of August, when rain finally occurred. A clear or slightly overcast sky prevailed. Five dry hot wind days were recorded. There were 31 dry hot wind days with air humidity below 30% from April to August. The weather conditions in 2024 were extreme for spring barley vegetation compared to the previous five years and low productive moisture was observed. In the first ten days of June, high air temperatures between +28 and +38 °C were recorded and in the period of May–June, there was a lack of precipitation. Precipitation was 5.0 mm in June and 5.9 mm in July. The air temperature in the summer months was the highest in August +36.7 °C.

Research material: barley seeds and plant varieties selected by the Federal Research Center of Agroecology RAS and the FSBSI Agricultural Research Center Donskoy (

Table 1. List and characteristics of Hordeum vulgare L. varieties.

Variety Name	Brief Description	Origin
Kamyshinsky 23	High productivity, lodging-resistant	Federal Research Center of Agroecology, Complex Melioration and Protective Afforestation of RAS, Volgograd, Russia
Medicum 139	High-growing, early maturing, large-grained
Medicum 200	Drought-tolerant, high tillering
Novonikolaevsky	Large grains, high tillering
Dmitrievsky 5	High-growing, highly disease-resistant
Ratnik	Drought-tolerant, heat-tolerant, moderately disease-resistant	FSBSI Agricultural Research Center Donskoy, Zernograd, Rostov region
Azimut	Drought-tolerant, heat-tolerant
Fedos	Drought-tolerant, early maturing
Format	Drought-tolerant, disease-resistant
Shchedriy	Medium maturity, drought-tolerant, lodging-resistant
Leon	Fast-ripening, large-grained

).

The TOR device, manufactured by Concern GRANIT, was initially designed for electromagnetic therapy [59,60] and then remodeled for agriculture purposes [61]. The pulse frequency for remote seed treatment with the EMF TOR device was set to 58 Hz. At a distance of 10 cm from the TOR device, the periodic PEMF magnetic component was 1.5 ± 0.2 μT, the electric component did not exceed 210 ± 30 V/m, and the radiation power density at a frequency of 2.45 GHz did not exceed 36 μW/cm² (Figure 1).

To study the effects of EMF treatment on the sowing qualities of seeds and the growth of seedlings, depending on the exposure duration and the intra-day circadian rhythms, as well as the impact on the further development, reproductive capacity, and quality of barley plants, depending on the varietal response of genotypes and the type of treatment, a series of laboratory and field experiments were carried out based on two methodological approaches: 1—the treatment of air-dried seeds before sowing; 2—the treatment of seeds in soil after sowing.

Experimental procedures:

Experiment 1, 2023—lab study. Dry seeds (Novonikolaevsky variety) underwent EMF treatment using the TOR device. The variants included the following: control—no EMF treatment—and experimental variants with EMF treatment at exposure durations of (1) 5 min; (2) 10 min; (3) 15 min; and (4) 30 min.

We selected the exposure times of 5, 10, and 15 min based on recommendations by the authors of a study [50]. This choice was made because their study noted changes in the biochemical parameters of sunflower seedlings treated with EMFs. Longer exposure durations (about an hour) reduced grain germination and the seedling size [48]; therefore, the maximum exposures we used were half an hour to prevent the development of seed stress caused by overtreatment with EMFs. Germination was carried out in Petri dishes, with 4 replicates, each containing 50 seeds. Lab measurements of the germination, length, and growth rate of coleoptile and rootlets were taken 70 h after sowing.

Experiment 2, 2023—lab study. The variants were based on the time of day during the treatment period: 5:00, 7:00, 9:00, 11:00 am, and 01:00 pm. Dry seeds were treated with EMFs for 10 min before sowing. Each variant included five replicates, with 50 seeds each (Novonikolaevsky variety). The control received no EMF treatment. Germination was carried out in CS-200 PCS climatostat. The germination energy, lab germination, growth rate, and rootlet length after 48 and 120 h of germination were recorded.

Experiment 3, 2023—small-plot field study. The variants included a control with no treatment and EMF treatment of dry seeds before sowing (in bags). The EMF exposure duration was 10 min. The experimental area was 1.80 × 50 m². Each variant included four replicates. The Novonikolaevsky variety was used.

Experiment 3, 2024—large-plot field study. The variants and experimental area included a control without treatment and EMF treatment of dry seeds before sowing (in bags). The treatment was carried out in morning hours for 15 min. The Medicum 139 variety was used.

The field germination, biometric parameters of the plants at different development stages, grain yield, and quality indicators were measured.

Experiment 4, 2023—small-plot field study. Seeds were treated in the soil after sowing. For this purpose, the battery-powered (brand) TOR device was mounted on a 1.5 m high tripod, directed at the experimental field area, and switched on for 15 min. The approximate total treatment area coverage using this method can reach up to 10 Ha, according to the manufacturer. In this experiment, the total treated area was about 5 Ha. EMF treatment exposure lasted 15 min. The control received no treatment. The area of experimental plots was 1.80 × 50 m². Each variant included four randomly placed replicates. The Novonikolaevsky variety was used in 2023 and 11 varieties of barley (Table 1) were used in 2024.

The field germination, biometric parameters of the plants at different development stages, grain yields, and quality indicators were measured.

Cultivation: Field sowing was carried out with the CC-11 Alpha seed planter. The seeds were placed at a depth of 3.5–4 cm and a sowing rate of 3.5 million germinated seeds per 1 Ha. Fall fallow (autumn-plowed fallow) was used as a precursor. Pre-sowing cultivation was carried out in spring.

Data and observations: The germination of seeds in the laboratory was determined according to the method in GOST-R 13056.6-97. The experiment was conducted in a CS-200 PCS climatostat. After 14 days, the development of seedlings was evaluated and their growth rate (coleoptile and roots) was calculated using the standard formula V = (L0 − Ln)/(t0 − tn), where V is the growth rate, mm/h; L0 is the initial length (mm) at t0 (h); and Ln is the length (mm) at the time of measurement at tn (h). The action effect coefficient (AEC, experience/control) of the EMF treatment was calculated as a ratio of the experimental values to the control values. The action relative effect (AE, %) was calculated as the percentage deviation of the experimental parameter relative to the control.

The zearalenone grain content was measured according to [62,63]. The phytohormone quantitative content was calculated according to [64].

Field trials were carried out in accordance with generally accepted methods [65,66]. Data collections and observations were carried out in accordance with the Russian Federation State’s variety testing of agricultural crops [67] and the method for determining the seed growth force [68], as follows:

–

Germination rates and tillering coefficients were estimated with a 0.25 m² frame, with 4 replicates per variety on the 8th day after sowing.

–

Shoot emergence was determined visually in dug-up plants.

–

The plant stand density was determined by counting the plants within a 0.25 m² frame, with 4 replicates.

–

Biometric measurements and sheaf samplings were carried out within a 0.25 m² frame, with 4 replicates.

We used the basic formula for yield conversion, accounting for a 14% moisture content and 100% purity as the standard indicators (1):

Y = (X × (100 − W) × (100 − MA))/(100 × (100 − MSt)),

(1)

where Y is the yield at a standard moisture content of 14% and 100% purity, t/Ha;

X is the bunker yield, t/Ha;

W is the weediness, %;

MA is the actual grain moisture content, %;

MSt is the standard moisture content (14%).

Sheaf samples were harvested within a square meter frame according to [65]. The actual yield was harvested using a SAMPO ROSENLEW SR2010 combine harvester (Sampo Rosenlew, Pori, Finland).

The yield structure was measured at the beginning of the waxy maturity phase (before harvesting). The yield and grain quality parameters (crude protein, moisture, and fiber) were determined with the Infralum FT-12 spectrometer (manufactured by Lumex, Saint Petersburg, Russia), after harvesting and thrashing. The grain quality indicators were specified according to the GC Lumex M04-40-2005 methodology described in GOST-R 31691-2012.

The obtained data were processed using ANOVA statistical analysis in the EXEL 2010 program, according to standard methods. The agriculture yields obtained with EMF treatments using the TOR device were evaluated.

3. Results

Experiment 1—the effects of the EMF seed priming duration on the germination and development of barley Hordeum vulgare L. seedlings.

Treated and control seeds were germinated for three days. As a result of EMF treatment, the percentage of germinated seeds increased by 8–10% relative to the control and the total length of seedlings exceeded the control by 1.7–3.2 times depending on the exposure duration. The EMF biostimulating effect increased sharply as the exposure increased from 5 min. to 10 min. and remained consistently high up to 15 min. A longer exposure duration led to a decrease in the EMF efficiency, and after 30 min. of exposure, the seedling length became comparable with the 5 min. exposure duration (Figure 2).

The effects of different EMF exposure durations on the development rates of individual embryo parts also differed. Treatments for 5 min. and 30 min. stimulated the growth of primary roots (2.0–2.4 times) to a greater extent than coleoptiles (1.5–1.8 times) compared to the control. Exposure durations of 10–15 min. had a more positive effect on coleoptile elongation, with growth rates exceeding the control by more than three times (

Table 2. Growth rates of barley coleoptile and primary embryo root depending on the EMF treatment duration.

Treatment Option, Exposure Time	Speed of Growth				Attitude, Lcol/Lroot
	Coleoptile		Root
	V, mm/h	AEC	V, mm/h	AEC
Control, without treatment (c)	0.06 a		0.04 a		1.3
EMF—5 min (e)	0.09 ab	1.5	0.08 b	2.0	1.2
EMF—10 min (e)	0.21 c	3.5	0.11 c	2.8	1.9
EMF—15 min (e)	0.19 c	3.2	0.11 c	2.8	1.7
EMF—30 min (e)	0.11 b	1.8	0.10 bc	2.4	1.1

Note: AEC, e/c—action EMF effect coefficient, calculated as the ratio of the experimental value to the control; Lcol/Lroot—ratio of the coleoptile length to the root length in the variant. The table shows the average values in the variant; a, b, and c indicate the reliability of differences, where values with the same letter indicate no significant difference, with a probability of 95% according to Duncan’s test.

); that is, under the influence of EMF treatment, there was a change in the growth rate ratio and, accordingly, in the lengths of the coleoptiles and roots. At exposure durations of 5 min. and 30 min., the growth rate was lower and, at exposure durations of 10–15 min., it was higher than in the control (Table 2).

The observed effect of the EMF treatment on barley seeds not only may have been caused by the different sensitivity of embryonic organs to the duration of EMF exposure, but also indirectly indicates a shift in the hormonal balance or changes in the germinating seed enzyme activity. Based on the results of this experiment, exposure durations of 10–15 min., which demonstrated the most pronounced biostimulating EMF effect during the initial stages of seed ontogenesis, were selected for further studies.

Experiment 2—the response of spring barley seedlings to EMF seed treatment depending on the diurnal cycle.

In this experiment, we studied changes in the indicators during the initial period of the germination of seeds treated using EMFs for 10 min. at different hours of the day: from 5 am to 1 pm, in increments of two hours. The highest bioactivation effect of germination initiation and growth was observed in seeds treated from 7:00 to 9:00 am. On the second day, 10–18% more seeds had germinated in these variants and the lengths of the coleoptiles had exceeded those of the control by 1.6–1.9 times. On the fifth day, laboratory germination was 11–13% higher and the seedlings were 1.5 times longer. At later hours, the EMF seed treatment efficiency decreased (Figure 3).

Similar to the previous experiment, the EMF treatment of barley seeds resulted in a sharp increase in the seedling growth rate during the first two to three days of germination. The germination energy of the seedlings slowed down in the 7:00 and 9:00 treatment groups, although the seedling length remained 1.3 times higher than the control. In the control, during all five days of germination, the growth rate of the seedlings remained constant, averaging 0.35–0.37 mm/hour (

Table 3. Dynamics of seedling growth rates after EMF treatment of barley seeds at different hours of the day (10 min. of exposure).

EMF Treatment Option, Exposure Start Time	Growth Speed
	Seedling (0–48 h)		Seedling (48–120 h)		Seedling (0–120 h)
	V, mm/h	EAC	V, mm/h	EAC	V, mm/h	EAC
Control, without treatment	0.35 a		0.37 a		0.37 a
EMF—at 5:00	0.45 b	1.3	0.38 a	1.0	0.41 ab	1.1
EMF—at 7:00	0.57 bc	1.6	0.47 c	1.3	0.51 c	1.4
EMF—at 9:00	0.66 c	1.9	0.47 c	1.3	0.55 c	1.5
EMF—at 11:00	0.44 ab	1.3	0.42 b	1.1	0.43 b	1.2
EMF—at 13:00	0.34 a	1.0	0.42 b	1.1	0.39 a	1.1

Note: See Table 2.

).

The obtained results suggest that intra-day circadian rhythms somewhat affect the sensitivity of spring barley seeds to EMFs and that priming them before sowing is more effective when carried out in the morning, between 7:00 and 10:00.

Experiment 3, 2024—the effects of priming seeds with EMFs before sowing on plant development in the field, the yield, and the product quality of spring barley Hordeum vulgare L.

The pre-sowing EMF treatment of seeds of the Novonikolaevsky variety increased field germination by 5% vs. the control. The EMF treatment had no significant effect on the linear dimensions of the roots and leaves in the sprouting phase, but contributed to a significant increase in the root mass (e/c = 22%). Furthermore, it promoted the accelerated development of the root systems in experimental plants, the length of which twice exceeded that of the control (

Table 4. Effects of priming seeds with EMFs before sowing (10 min. exposure) on biometric parameters of plants and yield of barley Hordeum vulgare L.

Stage of Development	Indicator	Variant		e/c, %
		Control Without Treatment	EMF-Treated
Sprouts	Germination, %	83	88	5
	Root length, cm	16.9 ± 0.5	16.1 ± 0.5	0
	Root weight, mg	0.23 ± 0.03	0.28 * ± 0.02 *	22
	Leaf length, cm	20.7 ± 0.5	19.8 ± 0.5	0
	Leaf weight, mg	0.35 ± 0.02	0.36 ± 0.01	0
Tillering	Root length, cm	24.5 ± 4.5	36.7 ± 4.3 *	50
	Leaf length, cm	154.2 ± 34.9	150.1 ± 24.4	0
Grain biological maturity	Yield, t/Ha	2.29 ± 0.32	2.81 ± 0.24 *	23

Note: * Statistically significant difference vs. control (p < 0.05).

).

The conditions of the growing season of 2023 were quite favorable for the development of barley Hordeum vulgare L. The yield in the control group was 2.3 t/Ha, while it was 2.8 t/Ha in the experimental group, a 23% increase. Certain differences between the variants and the quality of the products obtained were noted. A comparison of the biochemical compositions revealed a 3% decrease in the protein content of the experimental grains vs. the control, which is a positive indicator according to malting barley standards.

The indicators were comparable in terms of the water and fiber content in both variants. Another important positive effect was a significant 2.4-fold decrease in the accumulation of hazardous mycotoxin zearalenone EMF-treated grains—a product of fungi of the genus Fusarium graminearum (Figure 4), although its content in both variants remained within permissible levels (<1 mg/kg) [69,70].

This can be explained by the immunostimulating effect of EMFs on plants or seeds, which prevents the development and/or metabolic activity of the phytopathogen [71,72].

Experiment 3, 2024—the pre-sowing EMF treatment of seeds of the Medicum 139 variety for 15 min. also increased the field germination, despite the unfavorable climatic conditions in 2024 (

Table 5. Effects of priming seeds with EMFs before sowing (15 min. exposure) on plant biometric parameters and yield of Hordeum vulgare L.

Stage of Development	Indicator	Experiment Variant		SSD05	e/c, %
		Control Without Treatment	EMF-Treated
Sprouts	Field germination, pcs./m2	54 (49–58)	59 (56–61)	4	5
Waxy grain maturity	Plant height, cm	62.3	67.2	2.4	8
	Productive stems, pcs./m2	280	312 *	29	11
	Ear length, cm	7.6	8.1 *	0.3	7
	Number of grains per ear, pcs.	15	18 *	2	20
Grain biological maturity	Yield, t/ha	1.37	1.52 *	0.13	11
	Weight of 1000 seeds, g	29.7	32.3 *	1.3	9
	Grain moisture, %	10.33	10.45	0.11	0
	Fiber content of grain, %	5.67	5.72	0.18	0
	Protein content of grain, %	16.1	17.2	0.9	7

Note: * Statistically significant difference vs. control (p < 0.05).

).

The treatment promoted the improved development of the assimilatory apparatus and enhanced the reproductive potential of plants due to the biostimulation of the synthesis and accumulation of key phytohormones. The content of auxins increased by 6.4% and that of gibberellins and cytokinins by 3–5%, compared to the control plants (Figure 5).

As a result, the number of productive stems per unit area in the experiment increased by 11%, the ear length by 7%, and the grain average number per ear by 20% vs. the control. The yield was 1.52 t/Ha, which was 11% higher than that of the control, and the 1000-seed weight was 9% higher. In contrast to the Novonikolaevsky variety, the biochemical parameters of the Medicum 139 variety did not differ significantly from the control, although there was a tendency for the protein content to increase by 7%.

Experiment 4—the effects of priming seeds with EMFs after sowing on plant development in the field, the yield, and the product quality of spring barley Hordeum vulgare L.

Another direction of the present research was to study the influence of EMFs on spring barley development when treating seeds after their sowing in the ground. The Novonikolaevsky variety generally obtained similar results in the experiment with the pre-sowing EMF seed treatment, but with a more pronounced positive effect. Field germination increased by 15%, the root mass of the seedlings by 22%, and the length of the root system and leaves in the tillering phase by 76% and 55%, respectively. The grain yield in the experimental variant exceeded that of the control by two times, reaching 4.6 t/Ha. The protein content decreased compared to experiment 3, aligning with brewery malting standards (

Table 6. Effects of EMF seed treatment after sowing in the ground (exposure duration of 15 min.) on biometric parameters and yield of Hordeum vulgare L.

Stage of Development	Indicator	Experiment Variant		e/c, %
		Control Without Treatment	EMF-Treated
Sprouts	Germination, %	83	98	15
	Root length, cm	16.9 ± 0.5	17.8 ± 0.5 *	5
	Root weight, mg	0.23 ± 0.03	0.28 ± 0.02 *	22
	Leaf length, cm	20.7 ± 0.5	22.0 ± 0.6	6
	Leaf weight, mg	0.35 ± 0.02	0.37 ± 0.01	6
Tillering	Root length, cm	24.5 ± 4.5	44.2 ± 5.8 *	76
	Leaf length, cm	154.2 ± 34.9	225 ± 34.7	55
Biological ripeness	Yield, t/ha	2.3 ± 0.3	4.6 ± 0.5	101
	Grain moisture, %	9.9 ± 0.2	9.9 ± 0.2	0
	Fiber content of grain, %	5.7 ± 0.3	6.3 ± 0.4	11
	Protein content of grain, %	14.0 ± 1.1	12.4 ± 0.9	−11

Note: * Statistically significant difference vs. control (p < 0.05).

).

In the following year, the response of different varieties to post-sowing treatment was studied in a field experiment, which allowed us to evaluate their varietal EMF responsiveness. The treatment showed a positive effect on plant growth in all varieties under drought conditions during the 2024 growing season (

Table 7. Effects of EMF priming of seeds after sowing in the ground (exposure duration of 15 min.) on biometric parameters of barley Hordeum vulgare L. varieties (2024).

Variety Name	Stem Height, cm			Productive Stems, pcs./m2			Spikelet Length, cm			Number of Grains Per Ear, pcs.
	Control	EMF	e/c, %	Control	EMF	e/c, %	Control	EMF	e/c, %	Control	EMF	e/c, %
Varieties of Volgograd selection
Medicum 139	62	68 *	10	152	164	8	6.2	6.8 *	10	16	17 *	6
Medicum 200	61	63	3	180	188	4	6.5	6.9 *	6	15	16 *	7
Kamyshinsky 23	58	61	5	198	208	5	6.5	7.1 *	9	17	17	0
Dmitrievsky 5	47	56 *	19	184	192	4	6.5	6.9 *	6	16	18 *	13
Novonikolaevsky	48	52	8	176	152 *	−14	6.5	7.2 *	11	14	16 *	14
Rostov breeding varieties
Ratnik	45	49 *	9	156	189 *	21	5.9	6.3 *	7	13	16 *	23
Fedos	35	38	9	152	172 *	13	5.8	6.2 *	7	11	14 *	27
Format	39	44 *	13	152	168 *	11	5.3	5.6	6	15	18 *	20
Azimut	52	58 *	12	180	204 *	13	4.9	5.1	4	17	19 *	12
Shchedriy	57	61	7	148	164 *	11	5.2	5.7 *	10	15	17 *	13
Leon	59	63	7	152	180 *	18	6.1	6.4	5	13	15 *	15
SSD05	5			12			0.4			1

Note: * Statistically significant difference vs. control (p < 0.05).

).

The stem height in the phase of milk ripeness increased from 3% (Kamyshinsky 23 variety) to 19% (Dmitrievsky five variety) and the ear length increased by 5–11%. The density of productive stalks exceeded that of the control from 4% in the Medicum 200 and Dmitrievsky 5 varieties to 21% in the Ratnik variety. Higher EMF efficiency was observed in varieties of the Rostov selection (e/c > 10%), with the only exception being the local Novonikolaevsky. In all experimental plants, except for the Kamyshinsky 23 variety, a significant increase in the ear grain number was observed. The EMF efficiency was 6–27% higher compared to the control, with the Fedos variety showing the highest responsiveness in this indicator.

The grain yield was determined as the whole set of studied traits, but their contributions differed. In the Volgograd selection group, the increase was more closely associated with an increase in the ear length (r = 0.75), while in the Rostov selection group, it was more closely associated with the plant height (r = 0.43). In terms of the actual yields among the varieties, the most sensitive to EMF treatment were the early maturing varieties Medicum 139 and Leon; their yields were 3.6–4.1 times higher than that of the control (

Table 8. Effects of EMF priming of seeds after sowing in the ground (exposure duration of 15 min.) on yields and product quality of barley Hordeum vulgare L. varieties (2024).

Variety Name	Grain Yield, t/Ha			Seed Content, % of Crude Weight
				Protein			Fiber
	Control	EMF	EAC	Control	EMF	AE,%	Control	EMF	AE,%
Varieties of Volgograd selection
Medicum 139	0.21	0.86 *	4.1	18.31	17.74 *	−3	5.02	5.02	0
Medicum 200	0.45	1.20 *	2.7	16.33	16.08	−2	5.06	4.96	−2
Kamyshinsky 23	0.32	0.50 *	1.6	18.01	17.95	0	5.45	5.77 *	6
Dmitrievsky 5	0.57	0.89 *	1.6	17.01	15.77 *	−7	5.38	5.20	−3
Novonikolaevsky	0,44	1.10 *	2.5	17.02	16.90	−1	6.01	5.14 *	−14
Varieties of Rostov selection
Ratnik	0.64	1.24 *	1.9	15.73	15.25	−3	5.33	5.05 *	−5
Fedos	0.46	0.64 *	1.4	16.99	17.31	2	5.02	5.06	1
Format	0.66	1.09 *	1.7	16.63	15.23 *	−8	4.87	5.45 *	12
Azimut	0.63	0.64	1.0	17.00	16.63	−2	5.77	6.01	4
Shchedriy	0.61	1.48 *	2.4	15.23	18.36 *	21	5.20	6.03 *	16
Leon	0.55	1.99 *	3.6	15.67	16.61 *	6	5.21	5.46 *	5
SSD05	0.18			0.56			0.24

Note: * Statistically significant difference vs. control (p < 0.05).

).

In other varieties, the coefficient of the yield increase under the influence of EMFs varied from EAC = 1.4 (Fedos variety) to EAC = 2.7 (Medicum 200 variety). The exception was the drought-tolerant variety Azimut, whose productivity in the experiment was close to that of the control (Table 7). The seed protein content of most varieties tended to decrease in variants under EMF treatment, but it decreased significantly in five varieties only. Among them, the Format variety (AE = 8%) stood out. An increase in the seed protein content was observed in two varieties of the Rostov selection—Leon (by 6%) and Shchedriy (by 21%). Changes in the fiber content in the seeds after the EMF treatments also exhibited varietal specificity. A significant increase was observed in four varieties (by 6–16%), a decrease was observed in two varieties (by 3–15%), and the content in five varieties was comparable to that of the control (Table 8).

4. Discussion

Due to differences in the reaction of the plant organism to external factors at various times of the day (circadian clock), it is possible to optimize the rate of morphogenesis and the effectiveness of adaptive reactions to stress factors by changing the content and activity of hormones in tissues, metabolic activity, etc. [73,74,75]. Increasing attention has been given to physical factors influencing seeds that cause eustress and exert a beneficial effect on the further development of plants. Among these, weak, non-ionized, non-thermal, electromagnetic nature-like technologies show promise as cheap, fast, non-invasive, and environmentally friendly methods. However, the maximum effectiveness of EMF seed treatments depends on various factors, including the sensitivity of the crop and variety to EMFs, the structure and age of seeds, physical characteristics, intensity and duration of exposure, the treatment method, etc. A number of studies have observed a positive effect on seed germination in laboratory conditions, while in the field, either no effect or a negative effect of EMFs has been reported. The pre-sowing treatment of buckwheat seeds resulted in a decrease in field germination by 11–20%, but ultimately, had a positive effect on the growth, yield, and nutritional quality of the harvested seeds of two buckwheat varieties [75]. In our studies, the pre-sowing EMF treatment of dry seeds of different barley varieties for 10–15 min increased the germination percentage both in laboratory and field conditions (from 5 to 18%) and the growth rate of seedlings increased by 2–3 times vs. the control. It was noted that the observed effect was higher when the EMF priming of seeds was performed in the morning hours between 7:00 and 11:00. The observed differences in the seed response may be associated with the EMF sensitivity of different species or with differences in the EMF physical characteristics.

Our studies also confirm the observations of other researchers [75,76] that changes in the balance of phytohormones under the influence of EMFs lead to the stimulation and development of the root system and an increase in the assimilation surface of plants, particularly due to an increase in the content of auxins. Subsequently, this contributed to an increase in the density of productive stems, ear length, seed setting, and 1000-seed weight. As a result, this led to an increase in yield—exceeding that of the control by an average of 10% with EMF treatment of dry seeds—as well as to a decrease in the protein content in the grain in some varieties compared to the control (by 3–22%), bringing them closer to the brewing standards. In addition, the content of zearalenone in the products decreased two-fold.

By studying the reaction of spring barley plants to various methods of remote EMF seed treatment with the TOR device, we were the first to show that the treatment of barley seeds in the field after sowing stimulated growth processes to a greater extent. At the same time, the level of increase in the yield of different varieties depended on their responsiveness to EMFs. Among all the varieties, only the Azimut variety turned out to be slightly sensitive. Medium-sensitivity varieties include Medicum 200, Novonikolaevsky, Ratnik, and Shchedry and weakly sensitive ones include Kamyshinsky 23, Dmitrievsky 5, Fedos, and Forma, the yield of which increased by 1.9–2.7 and 1.4–1.6 times, respectively. The most sensitive varieties, Medicum 139 and Leon, had a yield exceeding that of the control by 3.6–4.1 times. These results convincingly confirm that the treatment of plant seeds with physical stressors has great potential for practical use in agriculture. However, the reasons for the EMF sensitivity/non-adaptability of agricultural crop varieties require additional research in the field of genetics and molecular biology.

5. Conclusions

The technology of EMF barley seed treatment at early stages, displaying a regulatory effect on plant development, helps to improve plant adaptation to adverse environmental conditions. In the particularly dry lands of the Volgograd Region (Russia), this allows most varieties to maximally realize their reproductive potential, improving not only their quality, but also the safety of their products by reducing the accumulation of dangerous mycotoxins in grains. The presented results indicate the significant prospects for the widespread introduction of technologies for the remote EMF treatment of barley seeds with the TOR device in agricultural practice, especially in regions in which farming can be difficult, allowing for pre-sowing treatment at a distance of 5 to 900 m of large batches of seeds in warehouses or in the field after sowing.