Effect of Dielectric Barrier Discharge Cold Plasma on Pea Seed Growth

Evaluating micro-nano bubbles coupled with rice-crayfish co-culture systems: A field study promoting sustainable rice production intensification

Traditional rice-fish symbiosis systems efficiently use soil and water resources but the adverse effects of prolonged flooding on the stability of rice growth can be mitigated. The feasibility and efficacy of injecting micro-nano bubbles (MNBs) in rice-crayfish co-cultures was investigated in a 22-hectare field experiment conducted over five months. This injection significantly enhanced the growth of both rice and crayfish, and increased total nitrogen and phosphorus levels in the soil, thereby augmenting fertility. Analysis of dissolved oxygen (DO), water temperature and gene expression (rice and crayfish) clarified that micro-nano bubbles (MNBs) foster an optimal environment for rice root respiration, whereas rice establishes an optimal temperature for crayfish, thereby enhancing their activity and growth. Comparative analyses of gene expression profiles and metabolic pathway enrichment revealed that the injection of MNBs diversifies soil microbial communities and intensifies biological processes, such as plant hormone signal transduction. This was in marked contrast to the situation in our controls, rice monoculture (R) and micro-nano bubbles rice monoculture (MNB-R). The combination of rice-fish symbiosis with MNBs led to a 26.8 % increase in rice production and to an estimated 35 % improvement in economic efficiency. Overall, this research introduces an innovative and environmentally sustainable method to boost rice yields, thereby enhancing food security and providing additional income for farmers.

Effect of micro-nano bubbles on the remediation of saline-alkali soil with microbial agent

The widespread distribution of saline-alkali soil around the world affects the health of ecological systems and the development of the national economy by limiting the growth of plants. However, the commonly used remediation technologies have the drawbacks of low efficiency, high cost, and secondary pollution. This study investigated the feasibility and efficacy of novel combined micro-nanobubbles (MNBs) and microbial agent (MA) technology for the remediation of saline-alkali soil. The results demonstrated that the combined MA-MNBs method greatly renovated the properties of saline-alkali soil compared with the technologies of single utilization of MA or MNBs process in the laboratory. The method resulted in a reduction of soil electrical conductivity and pH levels, an improvement in soil fertility, and the formation of soil aggregates. Moreover, the method significantly impacted the growth of plants, particularly in plant length, dry weight, and rhizome elongation. Further high-throughput sequencing and gene expression analysis revealed that the MA-MNBs method enhanced the abundance of soil microbial community compared with single MA and MNBs treatment. Gene enrichment analysis revealed that the MA-MNBs method could compensate for the shortcomings of single MA treatment and enhance the expression of energy metabolism and salt stress-related genes attributed to MNBs treatment, thereby significantly improving the growth and development of plants. Consistently, 6115 kg/ha of rice was yielded in the field for the saline-alkali soils using this MA-MNBs method, with zero crops before remediation. This study provided a novel, efficient, and green strategy for the remediation of saline-alkali soil without adding any chemicals.

Application of cold argon plasma on germination, root length, and decontamination of soybean cultivars

Applying cold discharge plasma can potentially alter plants' germination characteristics by triggering their physiological activities. As a main crop in many countries, soybean was examined in the present study using cultivars such as Arian, Katoul, Saba, Sari, and Williams in a cold argon plasma. This study has been motivated by the importance of plant production worldwide, considering climate change and the increasing needs of human populations for food. This study was performed to inspect the effect of cold plasma treatment on seed germination and the impact of argon plasma on microbial decontamination was investigated on soybeans. Also, the employed cultivars have not been studied until now the radicals generated from argon were detected by optical emission spectrometry (OES), and a collisional radiative model was used to describe electron density. The germination properties, including final germination percentage (FGP), mean germination time (MGT), root length, and electrical conductivity of biomolecules released from the seeds, were investigated after the plasma treatments for 30, 60, 180, 300, and 420 s. The decontamination effect of the plasma on Aspergillus flavus (A.flavus) and Fusarium solani (F.solani) was also examined. The plasma for 60 s induced a maximum FGP change of 23.12 ± 0.34% and a lowest MGT value of 1.40 ± 0.007 days. Moreover, the ultimate root length was 56.12 ± 2.89%, in the seeds treated for 60 s. The plasma exposure, however, failed to yield a significant enhancement in electrical conductivity, even when the discharge duration was extended to 180 s or longer. Therefore, the plasma duration of 180 s was selected for the blotter technique. Both fungi showed successful sterilization; their infectivity inhibition was 67 ± 4 and 65 ± 3.1%, respectively. In general, the cold plasma used for soybeans in the present study preserved their healthy qualities and reduced the degree of fungal contamination.

Metabolomic and transcriptomic analysis of cold plasma promoting biosynthesis of active substances in broccoli sprouts

INTRODUCTION

Broccoli sprouts have great health and commercial value because they are rich in sulforaphane, a special bioactive compound that helps to prevent chronic diseases, such as cancer and cardiovascular disease.

OBJECTIVE

The aim of this study was to increase the levels of active substances in broccoli sprouts and understand their metabolic mechanisms.

METHODOLOGY

Metabolomics based on liquid chromatography-tandem mass spectrometry and transcriptome analysis were combined to analyse the enrichment of metabolites in broccoli sprouts treated with cold plasma.

RESULTS

After 2 min of cold plasma treatment, the contents of sulforaphane, glucosinolates, total phenols, and flavonoids, as well as myrosinase activity, were greatly improved. Transcriptomics revealed 7460 differentially expressed genes in the untreated and treated sprouts. Metabolomics detected 6739 differential metabolites, including most amino acids, their derivatives, and organic acids. Enrichment analyses of metabolomics and transcriptomics identified the 20 most significantly differentially expressed metabolic pathways.

CONCLUSIONS

Overall, cold plasma treatment can induce changes in the expression and regulation of certain metabolites and genes encoding active substances in broccoli sprouts.

Atmospheric pressure pin-to-plate cold plasma effect on physicochemical, functional, pasting, thermal, and structural characteristics of proso-millet starch

The present work aimed to study the influence of atmospheric pressure pin-to-plate cold plasma on the physicochemical (pH, moisture, and amylose content), functional (water & oil binding capacity, solubility & swelling power, paste clarity on storage, pasting), powder flow, thermal and structural (FTIR, XRD, and SEM) characteristics at an input voltage of 170-230 V for 5-15 min. The starch surface modification by cold plasma was seen in the SEM images which cause the surge in WBC (1.54 g/g to 1.93 g/g), OBC (2.22 g/g to 2.79 g/g), solubility (3.05-5.38% at 70 °C; 37.11-52.98% at 90 °C) and swelling power (5.39-7.83% at 70 °C; 25.67-35.33% at 90 °C) of starch. Reduction in the amylose content (27.82% to 25.07%) via plasma-induced depolymerization resists the retrogradation tendency, thereby increasing the paste clarity (up to ̴ 39%) during the 5 days of refrigerated storage. However, the paste viscosity is reduced after cold plasma treatment yielding low-strength starch pastes. The relative crystallinity of starch increased (37.35% to 45.36%) by the plasma-induced fragmented starch granules which would aggregate and broaden the gelatinization temperature, but these starch fragments reduced the gelatinization enthalpy. The fundamental starch structure is conserved as seen in FTIR spectra. Thus, cold plasma aids in the production of soluble, low-viscous, stable, and clear paste-forming depolymerized proso-millet starch.

Germination and First Stages of Growth in Drought, Salinity, and Cold Stress Conditions of Plasma-Treated Barley Seeds

Numerous works have demonstrated that cold plasma treatments constitute an effective procedure to accelerate seed germination under nonstress conditions. Evidence also exists about a positive effect of plasmas for germination under environmental stress conditions. For barley seeds, this work studies the influence of cold plasma treatments on the germination rate and initial stages of plant growth in common stress environments, such as drought, salinity, and low-temperature conditions. As a general result, it has been found that the germination rate was higher for plasma-treated than for untreated seeds. Plasma also induced favorable changes in plant and radicle dimensions, which depended on the environment. The obtained results demonstrate that plasma affects the biochemical metabolic chains of seeds and plants, resulting in changes in the concentration of biochemical growing factors, a faster germination, and an initially more robust plant growth, even under stress conditions. These changes in phenotype are accompanied by differences in the concentration of biomarkers such as photosynthetic pigments (chlorophylls a and b and carotenoids), reactive oxygen species, and, particularly, the amino acid proline in the leaves of young plants, with changes that depend on environmental conditions and the application of a plasma treatment. This supports the idea that, rather than an increase in seed water imbibition capacity, there are clear beneficial effects on seedling of plasma treatments.

Physicochemical Properties of Plasma-Activated Water and Its Control Effects on the Quality of Strawberries

In this study, the effects of plasma-activated water (PAW), generated by dielectric barrier discharge cold plasma at the gas–liquid interface, on the quality of fresh strawberries during storage were investigated. The results showed that, with the prolongation of plasma treatment time, the pH of PAW declined dramatically and the electrical conductivity increased significantly. The active components, including NO2−, NO3−, H2O2, and O2−, accumulated gradually in PAW, whereas the concentration of O2− decreased gradually with the treatment time after 2 min. No significant changes were found in pH, firmness, color, total soluble solids, malondialdehyde, vitamin C, or antioxidant activity in the PAW-treated strawberries (p > 0.05). Furthermore, the PAW treatment delayed the quality deterioration of strawberries and extended their shelf life. Principal component analysis and hierarchical cluster analysis showed that the PAW 2 treatment group demonstrated the best prolonged freshness effect, with the highest firmness, total soluble solids, vitamin C, and DPPH radical scavenging activity, and the lowest malondialdehyde and ∆E* values, after 4 days of storage. It was concluded that PAW showed great potential for maintaining the quality of fresh fruits and extending their shelf life.

EFFECTS OF COLD PLASMA ON CHLOROPHYLLS, CAROTENOIDS, ANTHOCYANINS, AND BETALAINS

Plasma is considered by several researchers to be the fourth state of matter. Cold plasma has been highlighted as an alternative to thermal treatments because heat induces less degradation of thermolabile bioactive compounds, such as natural pigments. In this review, we provide a compilation of the current information about the effects of cold plasma on natural pigments, such as the changes caused by plasma to the molecules of chlorophylls, carotenoids, anthocyanins, and betalains. As a result of the literature review, it is noted that can degrade cell membrane and promote damage to pigment storage sites; thereby releasing pigments and increasing their content in the extracellular space. However, the reactive species contained in the cold plasma can cause degradation of the pigments. Cold plasma is a promising technology for extracting pigments; however, case-by-case optimization of the extraction process is required.

Cold atmospheric plasma treatment improves the γ-aminobutyric acid content of buckwheat seeds providing a new anti-hypertensive functional ingredient

Buckwheat (BW) is rich in γ-aminobutyric acid (GABA), which has great potential as a functional anti-hypertensive food ingredient. This study utilized cold atmospheric plasma (CAP) to promote GABA accumulation in BW during germination. The effect of this approach on GABA enrichment and anti-hypertensive activity of BW along with its processing properties were investigated. The results indicated that CAP stress treatment (50 W for 40 s) of BW seeds followed by germination at 30 °C for 60 h resulted in a GABA content of 2.22 ± 0.06 mg/g, which was a 2.64-fold greater than that of pristine BW. Cracking of the seed coat, faster germination, and the activation of glutamate decarboxylase might be responsible for the GABA enrichment. Compared with pristine BW, the GABA-enriched BW powder showed a greater inhibitory effect on the angiotensin-converting enzyme, an increased degree of pre-gelatinization and elasticity when it was formed into a dough.

The Modulatory Effects of Non-Thermal Plasma on Seed’s Morphology, Germination and Genetics—A Review

Non-thermal plasma (NTP) is a novel and promising technique in the agricultural field that has the potential to improve vegetal material by modulating the expression of various genes involved in seed germination, plant immune response to abiotic stress, resistance to pathogens, and growth. Seeds are most frequently treated, in order to improve their ability to growth and evolve, but the whole plant can also be treated for a fast adaptive response to stress factors (heat, cold, pathogens). This review focuses mainly on the application of NTP on seeds. Non-thermal plasma treated seeds present both external and internal changes. The external ones include the alterations of seed coat to improve hydrophilicity and the internal ones refer to interfere with cellular processes that are later visible in metabolic and plant biology modifications. The usage of plasma aims to decrease the usage of fertilizers and pesticides in order to reduce the negative impact on natural ecosystem and to reduce the costs of production.

A comprehensive study on decontamination of food-borne microorganisms by cold plasma

Food-borne microorganisms are one of the biggest concern in food industry. Food-borne microorganisms such as Listeria monocytogenes, Escherichia coli, Salmonella spp., Vibrio spp., Campylobacter jejuni, Hepatitis A are commonly found in food products and can cause severe ailments in human beings. Hence, disinfection of food is performed before packaging is performed to sterilize food. Traditional methods for disinfection of microorganisms are based on chemical, thermal, radiological and physical principles. They are highly successful, but they are complex and require more time and energy to accomplish the procedure. Cold plasma is a new technique in the field of food processing. CP treatments has no or very low effect on physical, chemical and nutritional properties of food products. This paper reviews the effect of plasma processing on food products such as change in colour, texture, pH level, protein, carbohydrate, and vitamins. Cold plasma by being a versatile, effective, economical and environmentally friendly method provides unique advantages over commercial food processing technologies for disinfection of food.

Current Advancements in the Molecular Mechanism of Plasma Treatment for Seed Germination and Plant Growth

Low-temperature atmospheric pressure plasma has been used in various fields such as plasma medicine, agriculture, food safety and storage, and food manufacturing. In the field of plasma agriculture, plasma treatment improves seed germination, plant growth, and resistance to abiotic and biotic stresses, allows pesticide removal, and enhances biomass and yield. Currently, the complex molecular mechanisms of plasma treatment in plasma agriculture are fully unexplored, especially those related to seed germination and plant growth. Therefore, in this review, we have summarized the current progress in the application of the plasma treatment technique in plants, including plasma treatment methods, physical and chemical effects, and the molecular mechanism underlying the effects of low-temperature plasma treatment. Additionally, we have discussed the interactions between plasma and seed germination that occur through seed coat modification, reactive species, seed sterilization, heat, and UV radiation in correlation with molecular phenomena, including transcriptional and epigenetic regulation. This review aims to present the mechanisms underlying the effects of plasma treatment and to discuss the potential applications of plasma as a powerful tool, priming agent, elicitor or inducer, and disinfectant in the future.

Emerging cold plasma treatment and machine learning prospects for seed priming: a step towards sustainable food production

Seeds are vulnerable to physical and biological stresses during the germination process. Seed priming strategies can alleviate such stresses. Seed priming is a technique of treating and drying seeds prior to germination in order to accelerate the metabolic process of germination. Multiple benefits are offered by seed priming techniques, such as reducing fertilizer use, accelerating seed germination, and inducing systemic resistance in plants, which are both cost-effective and eco-friendly. For seed priming, cold plasma (CP)-mediated priming could be an innovative alternative to synthetic chemical treatments. CP priming is an eco-friendly, safe and economical, yet relatively less explored technique towards the development of seed priming. In this review, we discussed in detail the application of CP technology for seed priming to enhance germination, the quality of seeds, and the production of crops in a sustainable manner. Additionally, the combination treatment of CP with nanoparticle (NP) priming is also discussed. The large numbers of parameters need to be monitored and optimized during CP treatment to achieve the desired priming results. Here, we discussed a new perspective of machine learning for modeling plasma treatment parameters in agriculture for the development of synergistic protocols for different types of seed priming.

Effectiveness of chelating agent-assisted Fenton-like processes on remediation of glucocorticoid-contaminated soil using chemical and biological assessment: performance comparison of CaO2 and H2O2

Glucocorticoids (GCs) have drawn great concern due to widespread contamination in the environment and application in treating COVID-19. Most studies on GC removal mainly focused on aquatic environment, while GC behaviors in soil were less mentioned. In this study, degradation of three selected GCs in soil has been investigated using citric acid (CA)-modified Fenton-like processes (H₂O₂/Fe(III)/CA and CaO₂/Fe(III)/CA treatments). The results showed that GCs in soil can be removed by modified Fenton-like processes (removal efficiency gt; 70% for 24 h). CaO₂/Fe(III)/CA was more efficient than H₂O₂/Fe(III)/CA at low oxidant dosage (< 0.28-0.69 mmol/g) for long treatment time (> 4 h). Besides the chemical assessment with GC removal, effects of Fenton-like processes were also evaluated by biological assessments with bacteria and plants. CaO₂/Fe(III)/CA was less harmful to the richness and diversity of microorganisms in soil compared to H₂O₂/Fe(III)/CA. Weaker phytotoxic effects were observed on GC-contaminated soil treated by CaO₂/Fe(III)/CA than H₂O₂/Fe(III)/CA. This study, therefore, recommends CaO₂-based treatments to remediate GC-contaminated soils.

Germination of Phaseolus vulgaris L. Seeds after a Short Treatment with a Powerful RF Plasma

Seeds of common bean (Phaseolus vulgaris L.), of the Etna variety, were treated with low-pressure oxygen plasma sustained by an inductively coupled radiofrequency discharge in the H-mode for a few seconds. The high-intensity treatment improved seed health in regard to fungal contamination. Additionally, it increased the wettability of the bean seeds by altering surface chemistry, as established by X-ray photoelectron spectroscopy, and increasing surface roughness, as seen with a scanning electron microscope. The water contact angle at the seed surface dropped to immeasurably low values after a second of plasma treatment. Hydrophobic recovery within a month returned those values to no more than half of the original water contact angle, even for beans treated for the shortest time (0.5 s). Increased wettability resulted in accelerated water uptake. The treatment increased the bean radicle length, which is useful for seedling establishment in the field. These findings confirm that even a brief plasma treatment is a useful technique for the disinfection and stimulation of radicle growth. The technique is scalable to large systems due to the short treatment times.

Sequential Application of High-Voltage Electric Field Cold Plasma Treatment and Acid Blanching Improves the Quality of Fresh Carrot Juice (Daucus carota L.)

The study was aimed to investigate the combined effect of acid blanching (AB) and high-voltage electric field cold plasma (HVCP) on carrot juice quality. Before juice extraction, carrots were separated into three parts: control, blanched (100 °C for 5 min) with non-acidified water, and blanched with acidified water (35 g/L citric acid at pH 1.34). Carrot juice was then subjected to dielectric barrier discharge at 80 kV for 4 min. Results indicated that AB treatment significantly influenced the efficiency of HVCP. AB-HVCP resulted in antimicrobial synergism, which is an outcome of acidified NO₂^-, H₂O₂, O^-, and peroxynitrites (ONOO^-) or its precursor OH/NO₂, along with other species. In addition, plasma treatment also promotes the accumulation of coloring compounds, chlorogenic acid, and sugar contents by surface erosion of the epidermal layer, cis isomerization, rupturing of phenol-sugar and phenolic-cell matrix bonds, and depolymerized long-chain polysaccharides by cleavage of the glycoside bond. Therefore, AB-HVCP is a potential emerging hurdle strategy for fresh produce.

Temperature Stability and Effectiveness of Plasma-Activated Liquids over an 18 Months Period

Non-buffered plasma-activated liquids such as water and saline have shown bactericidal effects. In the present study, we investigated the anti-bacterial efficacy and stability of plasma-activated water (PAW) and plasma-activated saline (PAS), generated using a high voltage dielectric barrier discharge system. This study compares the potential of non-buffered plasma-activated liquids (PAL) for the inactivation of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) after storage of the solutions at five different temperatures for a storage time up to 18 months after their generation. The temperatures used were room temperature, 4 °C, −16 °C, −80 °C, −150 °C. Both PAW and PAS achieved 6 log reduction for both bacteria on the first day of their generation after 60 min contact time and they retained these effects after 18 months when stored at the lowest temperatures. Chemical analysis of PAL showed that plasma caused a drop in pH, generation of reactive oxygen species and nitrates, whereas no nitrites are detected in the system used. The concentrations of chemical species were affected by the storage at different temperatures and a thermocouple probe was used to investigate the freezing behaviour of the PAL.

A Coaxial Dielectric Barrier Discharge Reactor for Treatment of Winter Wheat Seeds

Non-thermal atmospheric pressure plasmas have been recently explored for their potential usage in agricultural applications as an interesting alternative solution for a potential increase in food production with a minor impact on the ecosystem. However, the adjustment and optimization of plasma sources for agricultural applications in general is an important study that is commonly overlooked. Thus, in the present work, a dielectric barrier discharge (DBD) reactor with coaxial geometry designed for the direct treatment of seeds is presented and investigated. To ensure reproducible and homogeneous treatment results, the reactor mechanically shakes the seeds during treatment, and ambient air is admixed while the discharge runs. The DBD, operating with argon and helium, produces two different chemically active states of the system for seed modification. The temperature evolution was monitored to guarantee a safe manipulation of seeds, whereas a physiological temperature was assured by controlling the exposure time. Both treatments led to a remarkable increase in wettability and acceleration in germination. The present study showed faster germination acceleration (60% faster after 24 h) and a lower water contact angle (WCA) (82% reduction) for winter wheat seeds by using the described argon discharge (with air impurities). Furthermore, the treatment can be easily optimized by adjusting the electrical parameters.

Applications of nonthermal plasma technology on safety and quality of dried food ingredients

Cold plasma technology is an efficient, environmental-friendly, economic and noninvasive technology; and in recent years these advantages placed this novel technology at the centre of diverse studies for food industry applications. Dried food ingredients including spices, herbs, powders and seeds are an important part of the human diet; and the growing demands of consumers for higher quality and safe food products have led to increased research into alternative decontamination methods. Numerous studies have investigated the effect of nonthermal plasma on dried food ingredients for food safety and quality purposes. This review provides critical review on potential of cold plasma for disinfection of dried food surfaces (spices, herbs and seeds), improvement of functional and rheological properties of dried ingredients (powders, proteins and starches). The review further highlights the benefits of plasma treatment for enhancement of seeds performance and germination yield which could be applied in agricultural sector in near future. Different studies applying plasma technology for control of pathogens and spoilage micro-organisms and modification of food quality and germination of dried food products followed by benefits and current challenges are presented. However, more systemic research needs to be addressed for successful adoption of this technology in food industry.

The Effects of Plasma on Plant Growth, Development, and Sustainability

Cold atmospheric or low pressure plasma has activation effects on seed germination, plant growth and development, and plant sustainability, and prior experimental studies showing these effects are summarized in this review. The accumulated data indicate that the reactive species generated by cold plasma at atmospheric or low pressure may be involved in changing and activating the physical and chemical properties, physiology, and biochemical and molecular processes in plants, which enhances germination, growth, and sustainability. Although laboratory and field experiments are still required, plasma may represent a tool for efficient adaptation to changes in the climate and agricultural environments.