rus
DOI: https://doi.org/10.22184/1993-8578.2023.16.6.354.361
The work is devoted to the issues of assessing the degree of stimulating effect of silver nanoparticles (AgNPs) on cress seeds and seedlings. As part of the study, a solution of silver nanoparticles obtained in a polyvinyl alcohol matrix was used for stimulation, ascorbic acid was used as a reducing agent, which makes it possible to classify the synthesized solutions as "green nanotechnologies". The use of silver nanoparticles in agriculture can improve the immunity of plants. This effect is due to bactericidal, bacteriostatic, fungicidal and antiviral properties of silver nanoparticles. In addition, silver nanoparticles are exogenous elicitors; therefore, they have a growth-stimulating effect. The results of the study show that the applied solutions of silver nanoparticles increase the energy of germination and seed germination, increase the biomass of dry matter, and the concentration of vitamin C in the ground part of cress. The greatest degree of accumulation of silver in the case of cress is observed in the roots. In this case, the excess of the permissible concentration of silver is not observed.
The work is devoted to the issues of assessing the degree of stimulating effect of silver nanoparticles (AgNPs) on cress seeds and seedlings. As part of the study, a solution of silver nanoparticles obtained in a polyvinyl alcohol matrix was used for stimulation, ascorbic acid was used as a reducing agent, which makes it possible to classify the synthesized solutions as "green nanotechnologies". The use of silver nanoparticles in agriculture can improve the immunity of plants. This effect is due to bactericidal, bacteriostatic, fungicidal and antiviral properties of silver nanoparticles. In addition, silver nanoparticles are exogenous elicitors; therefore, they have a growth-stimulating effect. The results of the study show that the applied solutions of silver nanoparticles increase the energy of germination and seed germination, increase the biomass of dry matter, and the concentration of vitamin C in the ground part of cress. The greatest degree of accumulation of silver in the case of cress is observed in the roots. In this case, the excess of the permissible concentration of silver is not observed.
Теги: cress seeds elicitor green technologies silver nanoparticles зеленые технологии кресс-салат наночастицы серебра элиситор
Original paper
EVALUATION OF THE EFFECT OF SILVER NANOPARTICLES ON THE GROWTH AND DEVELOPMENT OF CRESS
O.A.Farus1, Cand. of Sci. (Chemical), Docent, ORCID: 0000-0002-1426-6534 / farusok@yandex.ru
Abstract. The work is devoted to the issues of assessing the degree of stimulating effect of silver nanoparticles (AgNPs) on cress seeds and seedlings. As part of the study, a solution of silver nanoparticles obtained in a polyvinyl alcohol matrix was used for stimulation, ascorbic acid was used as a reducing agent, which makes it possible to classify the synthesized solutions as "green nanotechnologies". The use of silver nanoparticles in agriculture can improve the immunity of plants. This effect is due to bactericidal, bacteriostatic, fungicidal and antiviral properties of silver nanoparticles. In addition, silver nanoparticles are exogenous elicitors; therefore, they have a growth-stimulating effect. The results of the study show that the applied solutions of silver nanoparticles increase the energy of germination and seed germination, increase the biomass of dry matter, and the concentration of vitamin C in the ground part of cress. The greatest degree of accumulation of silver in the case of cress is observed in the roots. In this case, the excess of the permissible concentration of silver is not observed.
Keywords: silver nanoparticles, cress seeds, elicitor, green technologies
For citation: O.A. Farus. Evaluation of the effect of silver nanoparticles on the growth and development of cress. NANOINDUSTRY. 2023. V. 16, no. 6. PP. 354–361. https://doi.org/10.22184/1993-8578.2023.16.6.354.361.
INTRODUCTION
Nanotechnology is considered to be one of the fastest growing branches of modern science. Nowadays, nanotechnology has been introduced into all spheres of modern life practically. Expanding application areas of nanoparticles and nanomaterials based on them leads to an increase in their industrial production. At the same time, it should be remembered that active introduction of any technology into the domestic life requires significant increase in the number of studies to determine measures for their safe use. Nanotechnology is no exception. The safe use of nanoparticles is associated with the need to assess their impact on the living organisms environment. At the same time, it should be noted that there is contradictory information on the results of study on response of test objects on nanoparticles presence in our environment.
The most widespread use of nanoparticles has been in crop production in the form of colloidal silver. Colloidal silver was first registered in crop production in 2014. This substance is a multiphase heterogeneous system that contains silver particles ranging in size from 1 to 100 nm, i.e. colloidal silver is a silver nanoparticle-based preparation. Now, several silver nanoparticle-based preparations are known to be used in crop production, such as AgBion-2, Zerox, and Serebromedin. The number of such preparations is growing rapidly. The wide application of silver nanoparticles is not accidental. Silver nanoparticles have become very widespread due to the fact that they have bactericidal, bacteriostatic, fungicidal and antiviral properties [1, 5–12]. It is important to note that microorganisms do not develop immunity against these drugs, unlike antibiotics.
Current studies show that, with respect to plants, silver nanoparticles activity is not limited to the actions described above. Silver nanoparticles for plants act as an exogenous elicitor. Elicitors are defined as factors that induce a number of non-specific defense responses in plants. This phenomenon is also called nonspecific adaptation syndrome. The triggering of these reactions allows plants to prepare in advance to repel future attack. Silver nanoparticles as elistors stimulate reactive oxygen species (ROS) production, such as hydrogen peroxide Н2О2, superoxide anion radical О2–, hydroxyl radical OH. ROSs contribute not only to plants systemic resistance development, but also directly affect bacterial and fungal pathogens.
In addition to elicitor action, silver nanoparticles are powerful growth stimulators. The growth-stimulating effect is due to blocking of ethylene receptors. Ethylene (С2Н4) is an aging, stress and maturation hormone for plants. Blocking ethylene receptors leads to prolongation of growing season in plants. The effects of silver nanoparticles are often compared to vaccination.
On the other hand, silver is a heavy metal. According to Russian sanitary norms, silver belongs to the second class of hazardous substances, i.e. "highly hazardous substance" and its excessive accumulation in living organisms can lead to their death or to a significant inhibition of development [9].
RESEARCH METHODS
Therefore, it is important to experimentally evaluate the effects of silver nanoparticles on different plant species. Cress was selected to evaluate the effect of silver nanoparticles on plants. Cress belongs to bioindicator plants. It is an annual vegetable plant with increased sensitivity to soil contamination by heavy metals, as well as to air pollution by gaseous emissions from motor vehicles.
As a bioindicator, it is convenient because the effect of stresses can be studied simultaneously on a large number of plants with a small working area, and it has a very short germination and maturation time, as well as has almost one hundred percent germination rate, which is very dependent on the degree of environmental pollution. In addition, shoots and roots of this plant under pollutants influence undergo noticeable morphological changes (stunted growth and curvature of shoots, reduction of length and weight of roots, as well as number and weight of seeds).
Silver nanoparticles were prepared by sol-gel technology by reducing silver ions with ascorbic acid in polyvinyl alcohol medium [12]:
Ag+ + C6H8O6 = AgNPs + C6H6O6.
This nanoparticles production method can be conditionally referred to "green nanotechnology". In this synthesis, ascorbic acid (vitamin C) is used as a reducing agent. Vitamin C is a catalyst for redox processes occurring in plant tissues, performing proton transfer function from the cell to the intercellular fluid. Ascorbic acid increases plant resistance to infections, stress and helps in the fight against chlorosis.
Polyvinyl alcohol, used in synthesis as a stabilizer of nanoparticles, is used in agriculture in the form of hydrogels that act as a moisture-retaining sorbent [3]. The study evaluated the effect of silver nanoparticles on cress in four ways:
seed germination rate and root system length;
dry matter biomass accumulation;
accumulation of silver in parts of cress seedlings and its comparison with permissible silver concentration;
accumulation of vitamin C in the above-ground parts of cress seedlings.
Silver content was determined in above-ground part and roots by atomic-adsorption analysis according to the method GOST 28353.3-2017 "Silver" on an atomic-adsorption spectrometer "Spectr-5-3". Vitamin C content was analyzed only in ground part of the plant by high-performance liquid chromatography on the "Orlant" unit.
RESULTS AND DISCUSSION
As part of experimental study, the effect of solutions containing silver nanoparticles on the germination of cress seeds was evaluated. For this purpose, three experimental sites were laid out. A cotton disk moistened with 5 ml of the following solutions was placed in three Petri dishes:
No. 1 – distilled water (control);
No. 2 – 1% solution of ascorbic acid in polyvinyl alcohol (AC/PVA);
No. 3 – silver nanoparticles solution (AgNPs).
Each cup was filled with 50 cress seeds and covered with a cotton disk with the same solution. The seeds were germinated for 7 days with constant recording of the results. To obtain reliable results, 3 samples were planted each. According to the observation data, germination energy (3 days) and germination (7 days) of cress seeds were determined (Table 1).
Observations shows that the highest rate of seed swelling was in the cup with AgNPs silver nanoparticles solution. Most of the seeds (92.67%) opened and started germination in cup number 3 on the 3rd day of observation, while 64.67% of the seeds opened in cup number 2 and 58% of the seeds opened in the first cup. Increase in germination energy and germination of seeds is a confirmation of elicitor action of silver nanoparticles. After seven days of observation, the root system of each seedling was measured and the results were plotted in the diagram (Fig.1).
The average root growth of seedlings in a Petri dish with distilled water was 0.71 cm, in a dish with ascorbic acid solution in polyvinyl alcohol was 1.24 cm, and in a Petri dish with silver nanoparticle solution was 1.87 cm.
The analysis of experimental data shows that the use of colloidal solution of silver nanoparticles AgNPs increases the germination energy and germination of cress seeds. It should be noted that there is an active growth of green mass. In a Petri dish with ascorbic acid, there is also an increase in seed germination intensity, which is expected, as ascorbic acid for plants is considered a regulator of water balance and metabolism, affects growth and disease resistance.
To evaluate the effect of silver nanoparticles on biomass accumulation processes, cress seeds were planted in microgreens trays, germination was carried out on a coconut mat. Two packets of seeds and 50 ml of solutions used in seed germination were placed in each tray:
No. 1 – distilled water (control);
No. 2 – 1% solution of ascorbic acid in polyvinyl alcohol (AC/PVA);
No. 3 – silver nanoparticles solution (AgNPs).
The samples were watered with similar solutions. Germination period of cress microgreens under experimental conditions was 14 days. After two weeks, the samples were weighed and their silver and vitamin C content was determined (Table 2).
When visually evaluating the seedlings, it should be noted that all samples have a high degree of germination, but in packet No.3 the growth of samples was more intense.
Analysis of experimental data shows that in packet No.3 there is a regular increase in silver concentration both in aboveground part of cress and roots. In the roots accumulates silver ions tens of times more, compared to the above-ground part of the plant. Interesting is the fact of silver accumulation in plant and in case of distilled water application. The obtained results allow us to conclude about "voluntary" accumulation of silver in plant and this conclusion is confirmed by the studies of other scientists [2, 6, 7]. It should also be noted that ascorbic acid solution application increases the silver assimilation degree by cress seedlings. This fact can be explained by transfer by ascorbic acid of silver from the substrate into a more accessible form for the plant.
Importantly, silver nanoparticles (AgNPs) solution application enhanced vitamin C production in watercress.
According to modern requirements, silver concentration in the range of 0.03–2.0 mg/kg is the natural concentration of silver in plants, and content of 0.5 mg/kg is considered normal [4, 8]. It is important to note that in none of the samples exceeding of natural silver concentrations in seedlings is observed, and in the above-ground part of seedlings silver concentration is at the lower limit of the norm.
CONCLUSIONS
Thus, the conducted research results allow us to draw the following general conclusions:
PEER REVIEW INFO
Editorial board thanks the anonymous reviewer(s) for their contribution to the peer review of this work. It is also grateful for their consent to publish papers on the journal’s website and SEL eLibrary eLIBRARY.RU.
Declaration of Competing Interest. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
EVALUATION OF THE EFFECT OF SILVER NANOPARTICLES ON THE GROWTH AND DEVELOPMENT OF CRESS
O.A.Farus1, Cand. of Sci. (Chemical), Docent, ORCID: 0000-0002-1426-6534 / farusok@yandex.ru
Abstract. The work is devoted to the issues of assessing the degree of stimulating effect of silver nanoparticles (AgNPs) on cress seeds and seedlings. As part of the study, a solution of silver nanoparticles obtained in a polyvinyl alcohol matrix was used for stimulation, ascorbic acid was used as a reducing agent, which makes it possible to classify the synthesized solutions as "green nanotechnologies". The use of silver nanoparticles in agriculture can improve the immunity of plants. This effect is due to bactericidal, bacteriostatic, fungicidal and antiviral properties of silver nanoparticles. In addition, silver nanoparticles are exogenous elicitors; therefore, they have a growth-stimulating effect. The results of the study show that the applied solutions of silver nanoparticles increase the energy of germination and seed germination, increase the biomass of dry matter, and the concentration of vitamin C in the ground part of cress. The greatest degree of accumulation of silver in the case of cress is observed in the roots. In this case, the excess of the permissible concentration of silver is not observed.
Keywords: silver nanoparticles, cress seeds, elicitor, green technologies
For citation: O.A. Farus. Evaluation of the effect of silver nanoparticles on the growth and development of cress. NANOINDUSTRY. 2023. V. 16, no. 6. PP. 354–361. https://doi.org/10.22184/1993-8578.2023.16.6.354.361.
INTRODUCTION
Nanotechnology is considered to be one of the fastest growing branches of modern science. Nowadays, nanotechnology has been introduced into all spheres of modern life practically. Expanding application areas of nanoparticles and nanomaterials based on them leads to an increase in their industrial production. At the same time, it should be remembered that active introduction of any technology into the domestic life requires significant increase in the number of studies to determine measures for their safe use. Nanotechnology is no exception. The safe use of nanoparticles is associated with the need to assess their impact on the living organisms environment. At the same time, it should be noted that there is contradictory information on the results of study on response of test objects on nanoparticles presence in our environment.
The most widespread use of nanoparticles has been in crop production in the form of colloidal silver. Colloidal silver was first registered in crop production in 2014. This substance is a multiphase heterogeneous system that contains silver particles ranging in size from 1 to 100 nm, i.e. colloidal silver is a silver nanoparticle-based preparation. Now, several silver nanoparticle-based preparations are known to be used in crop production, such as AgBion-2, Zerox, and Serebromedin. The number of such preparations is growing rapidly. The wide application of silver nanoparticles is not accidental. Silver nanoparticles have become very widespread due to the fact that they have bactericidal, bacteriostatic, fungicidal and antiviral properties [1, 5–12]. It is important to note that microorganisms do not develop immunity against these drugs, unlike antibiotics.
Current studies show that, with respect to plants, silver nanoparticles activity is not limited to the actions described above. Silver nanoparticles for plants act as an exogenous elicitor. Elicitors are defined as factors that induce a number of non-specific defense responses in plants. This phenomenon is also called nonspecific adaptation syndrome. The triggering of these reactions allows plants to prepare in advance to repel future attack. Silver nanoparticles as elistors stimulate reactive oxygen species (ROS) production, such as hydrogen peroxide Н2О2, superoxide anion radical О2–, hydroxyl radical OH. ROSs contribute not only to plants systemic resistance development, but also directly affect bacterial and fungal pathogens.
In addition to elicitor action, silver nanoparticles are powerful growth stimulators. The growth-stimulating effect is due to blocking of ethylene receptors. Ethylene (С2Н4) is an aging, stress and maturation hormone for plants. Blocking ethylene receptors leads to prolongation of growing season in plants. The effects of silver nanoparticles are often compared to vaccination.
On the other hand, silver is a heavy metal. According to Russian sanitary norms, silver belongs to the second class of hazardous substances, i.e. "highly hazardous substance" and its excessive accumulation in living organisms can lead to their death or to a significant inhibition of development [9].
RESEARCH METHODS
Therefore, it is important to experimentally evaluate the effects of silver nanoparticles on different plant species. Cress was selected to evaluate the effect of silver nanoparticles on plants. Cress belongs to bioindicator plants. It is an annual vegetable plant with increased sensitivity to soil contamination by heavy metals, as well as to air pollution by gaseous emissions from motor vehicles.
As a bioindicator, it is convenient because the effect of stresses can be studied simultaneously on a large number of plants with a small working area, and it has a very short germination and maturation time, as well as has almost one hundred percent germination rate, which is very dependent on the degree of environmental pollution. In addition, shoots and roots of this plant under pollutants influence undergo noticeable morphological changes (stunted growth and curvature of shoots, reduction of length and weight of roots, as well as number and weight of seeds).
Silver nanoparticles were prepared by sol-gel technology by reducing silver ions with ascorbic acid in polyvinyl alcohol medium [12]:
Ag+ + C6H8O6 = AgNPs + C6H6O6.
This nanoparticles production method can be conditionally referred to "green nanotechnology". In this synthesis, ascorbic acid (vitamin C) is used as a reducing agent. Vitamin C is a catalyst for redox processes occurring in plant tissues, performing proton transfer function from the cell to the intercellular fluid. Ascorbic acid increases plant resistance to infections, stress and helps in the fight against chlorosis.
Polyvinyl alcohol, used in synthesis as a stabilizer of nanoparticles, is used in agriculture in the form of hydrogels that act as a moisture-retaining sorbent [3]. The study evaluated the effect of silver nanoparticles on cress in four ways:
seed germination rate and root system length;
dry matter biomass accumulation;
accumulation of silver in parts of cress seedlings and its comparison with permissible silver concentration;
accumulation of vitamin C in the above-ground parts of cress seedlings.
Silver content was determined in above-ground part and roots by atomic-adsorption analysis according to the method GOST 28353.3-2017 "Silver" on an atomic-adsorption spectrometer "Spectr-5-3". Vitamin C content was analyzed only in ground part of the plant by high-performance liquid chromatography on the "Orlant" unit.
RESULTS AND DISCUSSION
As part of experimental study, the effect of solutions containing silver nanoparticles on the germination of cress seeds was evaluated. For this purpose, three experimental sites were laid out. A cotton disk moistened with 5 ml of the following solutions was placed in three Petri dishes:
No. 1 – distilled water (control);
No. 2 – 1% solution of ascorbic acid in polyvinyl alcohol (AC/PVA);
No. 3 – silver nanoparticles solution (AgNPs).
Each cup was filled with 50 cress seeds and covered with a cotton disk with the same solution. The seeds were germinated for 7 days with constant recording of the results. To obtain reliable results, 3 samples were planted each. According to the observation data, germination energy (3 days) and germination (7 days) of cress seeds were determined (Table 1).
Observations shows that the highest rate of seed swelling was in the cup with AgNPs silver nanoparticles solution. Most of the seeds (92.67%) opened and started germination in cup number 3 on the 3rd day of observation, while 64.67% of the seeds opened in cup number 2 and 58% of the seeds opened in the first cup. Increase in germination energy and germination of seeds is a confirmation of elicitor action of silver nanoparticles. After seven days of observation, the root system of each seedling was measured and the results were plotted in the diagram (Fig.1).
The average root growth of seedlings in a Petri dish with distilled water was 0.71 cm, in a dish with ascorbic acid solution in polyvinyl alcohol was 1.24 cm, and in a Petri dish with silver nanoparticle solution was 1.87 cm.
The analysis of experimental data shows that the use of colloidal solution of silver nanoparticles AgNPs increases the germination energy and germination of cress seeds. It should be noted that there is an active growth of green mass. In a Petri dish with ascorbic acid, there is also an increase in seed germination intensity, which is expected, as ascorbic acid for plants is considered a regulator of water balance and metabolism, affects growth and disease resistance.
To evaluate the effect of silver nanoparticles on biomass accumulation processes, cress seeds were planted in microgreens trays, germination was carried out on a coconut mat. Two packets of seeds and 50 ml of solutions used in seed germination were placed in each tray:
No. 1 – distilled water (control);
No. 2 – 1% solution of ascorbic acid in polyvinyl alcohol (AC/PVA);
No. 3 – silver nanoparticles solution (AgNPs).
The samples were watered with similar solutions. Germination period of cress microgreens under experimental conditions was 14 days. After two weeks, the samples were weighed and their silver and vitamin C content was determined (Table 2).
When visually evaluating the seedlings, it should be noted that all samples have a high degree of germination, but in packet No.3 the growth of samples was more intense.
Analysis of experimental data shows that in packet No.3 there is a regular increase in silver concentration both in aboveground part of cress and roots. In the roots accumulates silver ions tens of times more, compared to the above-ground part of the plant. Interesting is the fact of silver accumulation in plant and in case of distilled water application. The obtained results allow us to conclude about "voluntary" accumulation of silver in plant and this conclusion is confirmed by the studies of other scientists [2, 6, 7]. It should also be noted that ascorbic acid solution application increases the silver assimilation degree by cress seedlings. This fact can be explained by transfer by ascorbic acid of silver from the substrate into a more accessible form for the plant.
Importantly, silver nanoparticles (AgNPs) solution application enhanced vitamin C production in watercress.
According to modern requirements, silver concentration in the range of 0.03–2.0 mg/kg is the natural concentration of silver in plants, and content of 0.5 mg/kg is considered normal [4, 8]. It is important to note that in none of the samples exceeding of natural silver concentrations in seedlings is observed, and in the above-ground part of seedlings silver concentration is at the lower limit of the norm.
CONCLUSIONS
Thus, the conducted research results allow us to draw the following general conclusions:
- application of silver nanoparticles (AgNPs) solutions in polyvinyl alcohol matrix, obtained by reduction of silver ions with ascorbic acid promotes increasing of germination rate and biomass accumulation by cress;
- there is no doubt that the use of silver nanoparticles solutions (AgNPs) contributes to increased accumulation of silver in plants, with significant accumulation occurs in the root part of the plant, in the case of cress, the use of ground part is safe for health, because the concentration of silver does not exceed permissible concentrations;
- using the silver nanoparticle solutions (AgNPs) for root crops requires extra caution;
- application of silver nanoparticles solutions (AgNPs) leads to an increase in concentration of vitamin C in the above-ground part of cress seedlings, which is an undoubted advantage of using silver nanoparticles in cress agrotechnics.
PEER REVIEW INFO
Editorial board thanks the anonymous reviewer(s) for their contribution to the peer review of this work. It is also grateful for their consent to publish papers on the journal’s website and SEL eLibrary eLIBRARY.RU.
Declaration of Competing Interest. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Readers feedback
