rus
Issue #6/2020
V.N.Zelenkov, V.V.Latushkin, V.V.Potapov, V.V.Karpachov, V.M.Kosolapov, V.T.Sinegovskaya, M.I.Ivanova, A.A.Lapin, P.A.Vernik
Peculiarities of the concentration effect of hydrothermal nanosilica in the pre-sowing treatment of plant seeds upon indicators of the germinative energy and germinating ability in laboratory dark growth
Peculiarities of the concentration effect of hydrothermal nanosilica in the pre-sowing treatment of plant seeds upon indicators of the germinative energy and germinating ability in laboratory dark growth
DOI: 10.22184/1993-8578.2020.13.6.346.358
The research is devoted to the study of the influence of hydrothermal nanosilica in different concentrations (0.05%, 0.01%, 0.005%, 0.001% and 0.0005%) on seed germination of 11 agricultural crops (15 genotypes). Four types of reaction of germinating seeds to the effect of SiO2 nanoparticles in the specified concentration range have been established. These patterns are typical for both the "seed germinative energy" and "seed germinating ability" indicator, but they do not always coincide for the same crop and variety. In many cases hydrothermal nanosilica contributes to an increase in seed germinative energy (at an early stage of germination) to a greater extent than generating ability.
The research is devoted to the study of the influence of hydrothermal nanosilica in different concentrations (0.05%, 0.01%, 0.005%, 0.001% and 0.0005%) on seed germination of 11 agricultural crops (15 genotypes). Four types of reaction of germinating seeds to the effect of SiO2 nanoparticles in the specified concentration range have been established. These patterns are typical for both the "seed germinative energy" and "seed germinating ability" indicator, but they do not always coincide for the same crop and variety. In many cases hydrothermal nanosilica contributes to an increase in seed germinative energy (at an early stage of germination) to a greater extent than generating ability.
Теги: agricultural seeds genotypes germination germination energy hydrothermal nanosilica всхожесть генотипы гидротермальный нанокремнезем семена сельскохозяйственных культур энергия прорастания
INTRODUCTION
One of the promising directions to improve seed germination in open and protected ground is the use of plant growth regulators, in particular, nanosized forms of silica (HNS). The direction dealing with of isolation of nanodispersed silica of hydrothermal origin has been actively developing in Russia for the last 20 years [1–3].
Deep waters from the wells of the Mutnovskaya GeoPP (Kamchatka) hydrothermal power station are used as raw materials for obtaining HNS. The use of silica nanoparticles obtained from natural geothermal waters opens up prospects for large-scale use of the new natural resources for the development of nanotechnologies when creating innovative products. An essential point for such prospects are the HNS biologically active properties revealed as a result of many years of research by the authors, which contribute to an increase in the productivity of agricultural plants and animals [4–12]. The environmental safety of using this natural nanomaterial presents an important aspect [12].
Silica is formed in a hydrothermal solution from orthosilicic acid molecules found in the depths of hydrothermal deposits. After the solution reaches the surface its temperature decreases and it becomes supersaturated with respect to solubility of amorphous silica, which triggers nucleation and polycondensation of silicic acid molecules. As a result, colloidal particles of hydrated silica nSiO2×mH2O are formed in the solution. Due to dissociation of the surface silanol groups of SiOH and elimination of the H+ proton, the surface of particles acquires a negative electric charge. The electrostatic repulsion forces prevent coagulation of particles and determine the stability of colloidal silica in a hydrothermal solution. As a result, spherical silica nanoparticles of 5–100 nm radii are formed [1–3]. The content of SiO2 in silica sols using ultrafiltration membranes was brought by the authors of the article to 100–600 g / dm3. The density of the sols was in the range of 999–1,325 g / dm3, the dynamic viscosity was 1–150 mPa×s, the radii of the silica particles were 5–135 nm, and the zeta potential of the particles was (–32.4...–42.5) mV. Ultrafiltration provides for a fairly low content of impurities and stability of aqueous silica sols up to the highest SiO2 contents that we have been able to achieve in technological experiments – up to 600 g / dm3. This corresponds to a concentration of 1,500 times compared to the silica content in the initial hydrothermal solution and opens up prospects for practical use of the new natural mineral resources.
Application of the HNS in crop production and biotechnology can be considered as one of the promising environmentally friendly technological directions for nature-like technologies using mineral resources for crop production, veterinary medicine and biotechnologies [4–12].
Development of the physicochemical basics of biotechnology for the pre-sowing treatment of plant seeds with nanoparticles of various nature is necessary to understand the role of the genetic (varietal) and epigenetic factors of the chemical and physicochemical composition of both the seed coat and the location of reserve nutrients inside the seed, which activation and use begins with moistening seeds and creation of the conditions for germination both in the field and in the laboratory, inclusing a new factor of influence in the system of germinating seeds – nanoparticles of hydrothermal silica [13]. In connection with the active development of bionanotechnology in the agricultural science, the interaction of plants with nanoparticles of various natures at different stages of ontogenesis has been actively studied by scientists from different countries [14–21].
The first stage of plant vegetation is their germination in the habitat such conditions can be simulated in the laboratory to study the limiting factors of plant productivity [14]. Research in this direction in the conditions of creating uniformity of modeling the interaction processes of nanoparticles with seeds of different characteristics of various plant species makes it possible to classify the experimental data according to uniformity of the germinated seeds response in quantitative parameters of germinative energy and germinating ability, which has been standardized for different types of agricultural plants according to the conditions for evaluating these parameters in regulatory documents at the level of state standards (GOST) or technical specifications for the cases little used in practice or for the new species of the plants introduced in new climatic conditions in the territory of Russia.
The ultimate goal of any systemic scientific research is the practical application of new knowledge and methodology of techniques in varietal technologies of pre-sowing treatment in crop production of the open and protected ground, as well as obtaining a new type of food products – germinated seeds and microgreens with increased biological value in terms of the content of physiologically active biochemical components as products of enzymatic processes of heterotrophic seed nutrition in the dark or under natural solar or artificial LED illumination, which has been widely used in recent years in practice when modeling the plant habitat and its changes in agrobiotechnological systems [14].
The purpose of this work was a screening experimental assessment of the seeds response of different agricultural crops to their pre-sowing treatment with nanoparticles of hydrothermal silica in a single scale of nanoparticle concentrations during dark laboratory germination.
MATERIALS AND RESEARCH METHODS
In accordance with the experimental work purpose the germination of 11 agricultural crop seeds (vegetables, oilseeds, fodder, medicinal), differing in biological characteristics, genetic nature, chemical and physicochemical composition and structure of seeds and their peels have been studied for various purposes. In total, 15 genotypes have been studied, including different species, varieties and hybrids.
Germination of seeds was carried out in the dark according to GOST 12038-84 "Seeds of agricultural crops. Methods for determining germination" and GOST 22617.2-94 "Sugar beet seeds. Methods for determining germination, monogermity and good quality" as amended: a mineral wool substrate was used instead of filter paper. Germination was carried out in a synergotron chamber – an experimental model of the IDS 1.01 model (developed by the Institute for Development Strategies). Watering was carried out with distilled water as the substrate dried up. Germination temperature was 23–24 °С and threefold repetition was applied.
Pre-sowing treatment with hydrothermal silica nanoparticles was carried out by soaking the seeds for 2 hours in distilled water (control) and in aqueous sols of hydrothermal nanosilica (HNS) of various concentrations (0.05%, 0.01%, 0.005%, 0.001%, and 0005%). Soybean seeds were an exception where soaking was carried out for 15 minutes. In the course of preliminary experiments it was found that a further increase in duration of soaking does not lead to an increase in the amount of the aqueous solution with the preparation absorbed by the seeds, while the integrity of soybean seeds is disturbed and they are easily injured during sowing.
For all experiments, we used the initial aqueous HNS sol of 37.5 wt. % concentration of SiO2 nanoparticles obtained by ultrafiltration methods at the Far Eastern Branch of the RAS, FSBSI "Research Geotechnological Center" (Petropavlovsk-Kamchatsky) in 2018 from the hydrothermal solution of the Mutnovskaya hydrothermal power plant wells according to the method described in [1–3].
A working aqueous sol of the HNS of 2.5% concentration was prepared in advance from the initial aqueous 37.5% HNS concentrate by diluting it with distilled water.
Before the start of each experiment with seeds of a specific agricultural crop, fresh aqueous sols of nanosilica were prepared out of a 2.5% working aqueous sol of HNS using distilled water of the indicated concentrations. The prepared aqueous HNS sols of various concentrations were used in experiments on pre-sowing treatment of seeds immediately after preparation for no more than 30 minutes.
Figure 1 shows a distribution of silica nanoparticles obtained using the dynamic light scattering method. The first peak corresponds to the maximum distribution of nanoparticles, the second peak is due to the formation of aggregates of nanoparticles in a dispersed nanosystem. The modal hydrodynamic diameter of the HNS particles of the initial concentrate and its 2.5% sol used in the work is 9 nm (measurements were carried out at the National Research Center "Kurchatov Institute").
According to GOST 12038-84, the germinative energy and seed germinating ability were determined in the following periods: meadow clover – on the 3rd day (germinative energy) and 7th day (germinating ability), coriander – on the 6th and 15th days, respectively, alfalfa changeable – on the 4th and 7th days, meadow fescue and festulolium – on days 5 and 10, bent grass – 7 and 14, rapeseed – 3 and 7, radishes – on 3 and 6, table beets – 5 and 10, soybeans – 3 and 7 days, respectively. Seeds of sugar beet were germinated according to GOST 22617.2-94 for 4 days to determine the germinative energy and for 10 days – to determine the germinating ability. As regards the new fodder culture of the Abyssinian nougat, the GOST for germinating ability has not yet been developed for germination, therefore, the sowing properties in the experiment were determined by analogy with other rapidly germinating seeds – on days 3 and 7.
Since the purpose of this work was to compare the effects of hydrothermal nanosilica on 11 agricultural crops, all data on the sowing properties of seeds were recalculated into relative values – the change (increase) in germinative energy and germinating ability in % relative to the control seeds of a particular crop (i.e. without HNS processing). Thus, it becomes possible to compare and analyze the data obtained in the experiment for different crops.
The germinating ability of the original seeds used in the experiment (control) ranged from 51.4% (clover, variety Mars) to 98.1% (radish, variety Yubileiny) for different crops; the germinative energy varied in a much wider range (Table 1). All data presented in section "Results and their discussion" are compared with the indicated controls in relative units (in %).
RESULTS AND THEIR DISCUSSION
The use of nanosized silica during seed germination in the experiment made it possible to increase the seed germinative energy by a maximum of 10.5% in comparison with the control (soybean, Alena variety). At the same time, for a number of crops, the increase in seed germinative energy did not exceed 1% (rapeseed, varieties Antares and Ratnik, alfalfa variety Selena, clover meadow, varieties Mars and Pavlovsky). A small level of increased germinating ability is characteristic of all studied rapeseed and clover varieties. At the same time, the increase in the germinating ability of seeds of alfalfa variety Selena was 0.6%, and that of alfalfa variety Pastbishchnaya 88 – 1.2%.
The germinating ability of seeds with the use of HNS increased by a maximum of 8.3% compared to the control (sugar beet, hybrid Smena F1). However, for the same crops, which showed a minimum increase in seed germinative energy, the increase in germinative ability was also minimal, and did not exceed 1% (rapeseed, varieties Antares and Ratnik, alfalfa, variety Selena, meadow clover, varieties Mars and Pavlovsky). At the same time, the increase in germinative ability of seeds of alfalfa, variety Selena, was 0.4%, and that of alfalfa, variety Pasturenaya 88 – 1.3%. For coriander, variety Yantar, the increase in germination energy was up to a maximum of 5.1%, and the increase in germination rate was up to 0.7%.
A significant increase in seed germinative energy under the influence of treatment with silica nanoparticles (to a greater extent than germinating ability) in the experiment was also manifested, except coriander, in a number of other crops, especially Abyssinsky nougat, Lipchanin variety, and soybean, Alena variety. At the same time, HNS can stimulate a greater increase in the germinating ability than the germinative energy indicator (for example, sugar beet, hybrid Smena F1, Festulolium, Allegro variety).
Thus, the genetic factor plays a significant role in the formation of plant response to the use of hydrothermal nanosilica during seed germination in the dark mode.
Screening of seeds of different crops and varieties according to the reaction of energy and germinating ability indicators to the treatment with HNS of different concentrations (0.05%, 0.01%, 0.005%, 0.001% and 0005%) showed existence of several types of such reactions. Figures 2–9 show four generalized groups of crops, differing in the geometric form of the response-display on the graph illustrating dependence of the energy indicator (germinating ability) to the control, depending on the concentration of HNS in the water sol during presowing seed treatment. Different plants were distributed among groups by visualizing these diagrams reflecting the response forms of the seeds of the corresponding crops. Selected for the analysis were those crops and varieties in which the increase in germinative energy and seed germinating ability, when using HNC, exceeded 1%. We note that the identified four types of reactions can be traced both in the analysis of the germinative energy and germinating ability, however, complete coincidence is not found. This is probably due to the fact that the totality of manifestations of biochemical (specificity and activity of enzymes), biophysical (structure of the seed), chemical (chemical composition of seed nutrients) and physiological factors (features of germination) form the characteristic signs of "germinative energy" and "germinating ability" on the diagrams, which adds significant differences (change the ranking of the significance of factors) along with the specificity of genomes. However, in crops with an increase in indicators of the germinating ability and germinative energy of less than 1%, similar tendencies were observed in the type of response-reaction (according to the type of group 1 in germination – in rapeseed, variety Antares, in group 2 – in germination – in rape, variety Ratnik, clover, variety Mars, coriander, variety Yantar, groups 3 – by germination energy – clover, variety Mars, by germination – by clover, variety Pavlovsky, group 4 – by germination energy – alfalfa, variety Selena, rape, variety Ratnik and rape, variety Antares, clover, Pavlovsky variety, by germination rate – in alfalfa, Selena variety).
Group 1. The maximum increase after use of HNS is observed in the area of low and moderate concentrations of nanoparticles in terms of germinative energy: radish (Yubileiny variety), Abyssinsky nougat (Lipchanin variety), soybean (Alena variety), festulolium (Allegro variety) – Fig.2, according to the germinating ability: sugar beet (hybrid Smena F1), festulolium (Allegro variety), soybean (Alena variety) – Fig.3.
Group 2. The maximum increase after use of HNS mainly in the range of high and moderately high concentrations of nanoparticles in terms of germinative energy: table beet (Demetra variety), coriander (Yantar variety) – Fig.4, according to the germinating ability: table beet (Demetra variety), fescue (Kvart variety) – Fig.5.
Group 3. The maximum increase is observed mainly in the area of average concentrations of HNS (typical examples of germinative energy: sugar beet (hybrid Smena F1), fescue (Kvart variety), bent grass (VIK-2 variety) – Fig.6. according to the germinating ability: bent VIC-2), alfalfa (Pasture 88 variety) – Fig.7.
Group 4. It is characterized by the presence of two pronounced maxima and minima of the germinative energy – alfalfa (Pastbishnaya 88 variety) – Fig.8, according to the germinating ability – Abyssinsky nougat (Lipchanin variety) and radish (Yubileiny variety) – Fig.9.
CONCLUSIONS
The use of hydrothermal nanosilica affects the level and direction of plant metabolism, which leads to a change in plant properties. It can be assumed that the mechanisms of the HNS effect on plants will differ in different periods of ontogenesis. In general, the question of the effect of nanosilica on the stage of seed germination is still poorly developed. In this work, for the first time, experimental data were obtained on assessing the effect of hydrothermal nanosilica of different concentrations (0.05%, 0.01%, 0.005%, 0.001% and 0.0005%) on seed germination of 11 (15 genotypes) agricultural plants differing in economic use, biological properties, biochemical composition and physicochemical structure of the seed.
Four types of reaction of dark germination of seeds to the effect of hydrothermal silica nanoparticles in the concentration range from 0.0005% to 0.05% have been established. These patterns are typical for both the "seed germinative energy" and "seed germinating ability" indicator, but they do not always coincide for the same crop. Thus, the genetic and epigenetic factors of the chemical, biochemical and physicochemical and biophysical (structure of specific seeds) plant composition play a significant role in the formation of the response of specific plant seeds to the effect of natural silica nanoparticles of various concentrations during pre-sowing seed treatment.
The data obtained in the study can be useful for understanding the mechanisms of the effect of nanoparticles at the stage of seed germination, as well as for subsequent use for the development of biotechnologies for pre-sowing seed treatment in the open and protected ground crop production, as well as for obtaining a new type of food products – seed sprouts and microgreens. ■
One of the promising directions to improve seed germination in open and protected ground is the use of plant growth regulators, in particular, nanosized forms of silica (HNS). The direction dealing with of isolation of nanodispersed silica of hydrothermal origin has been actively developing in Russia for the last 20 years [1–3].
Deep waters from the wells of the Mutnovskaya GeoPP (Kamchatka) hydrothermal power station are used as raw materials for obtaining HNS. The use of silica nanoparticles obtained from natural geothermal waters opens up prospects for large-scale use of the new natural resources for the development of nanotechnologies when creating innovative products. An essential point for such prospects are the HNS biologically active properties revealed as a result of many years of research by the authors, which contribute to an increase in the productivity of agricultural plants and animals [4–12]. The environmental safety of using this natural nanomaterial presents an important aspect [12].
Silica is formed in a hydrothermal solution from orthosilicic acid molecules found in the depths of hydrothermal deposits. After the solution reaches the surface its temperature decreases and it becomes supersaturated with respect to solubility of amorphous silica, which triggers nucleation and polycondensation of silicic acid molecules. As a result, colloidal particles of hydrated silica nSiO2×mH2O are formed in the solution. Due to dissociation of the surface silanol groups of SiOH and elimination of the H+ proton, the surface of particles acquires a negative electric charge. The electrostatic repulsion forces prevent coagulation of particles and determine the stability of colloidal silica in a hydrothermal solution. As a result, spherical silica nanoparticles of 5–100 nm radii are formed [1–3]. The content of SiO2 in silica sols using ultrafiltration membranes was brought by the authors of the article to 100–600 g / dm3. The density of the sols was in the range of 999–1,325 g / dm3, the dynamic viscosity was 1–150 mPa×s, the radii of the silica particles were 5–135 nm, and the zeta potential of the particles was (–32.4...–42.5) mV. Ultrafiltration provides for a fairly low content of impurities and stability of aqueous silica sols up to the highest SiO2 contents that we have been able to achieve in technological experiments – up to 600 g / dm3. This corresponds to a concentration of 1,500 times compared to the silica content in the initial hydrothermal solution and opens up prospects for practical use of the new natural mineral resources.
Application of the HNS in crop production and biotechnology can be considered as one of the promising environmentally friendly technological directions for nature-like technologies using mineral resources for crop production, veterinary medicine and biotechnologies [4–12].
Development of the physicochemical basics of biotechnology for the pre-sowing treatment of plant seeds with nanoparticles of various nature is necessary to understand the role of the genetic (varietal) and epigenetic factors of the chemical and physicochemical composition of both the seed coat and the location of reserve nutrients inside the seed, which activation and use begins with moistening seeds and creation of the conditions for germination both in the field and in the laboratory, inclusing a new factor of influence in the system of germinating seeds – nanoparticles of hydrothermal silica [13]. In connection with the active development of bionanotechnology in the agricultural science, the interaction of plants with nanoparticles of various natures at different stages of ontogenesis has been actively studied by scientists from different countries [14–21].
The first stage of plant vegetation is their germination in the habitat such conditions can be simulated in the laboratory to study the limiting factors of plant productivity [14]. Research in this direction in the conditions of creating uniformity of modeling the interaction processes of nanoparticles with seeds of different characteristics of various plant species makes it possible to classify the experimental data according to uniformity of the germinated seeds response in quantitative parameters of germinative energy and germinating ability, which has been standardized for different types of agricultural plants according to the conditions for evaluating these parameters in regulatory documents at the level of state standards (GOST) or technical specifications for the cases little used in practice or for the new species of the plants introduced in new climatic conditions in the territory of Russia.
The ultimate goal of any systemic scientific research is the practical application of new knowledge and methodology of techniques in varietal technologies of pre-sowing treatment in crop production of the open and protected ground, as well as obtaining a new type of food products – germinated seeds and microgreens with increased biological value in terms of the content of physiologically active biochemical components as products of enzymatic processes of heterotrophic seed nutrition in the dark or under natural solar or artificial LED illumination, which has been widely used in recent years in practice when modeling the plant habitat and its changes in agrobiotechnological systems [14].
The purpose of this work was a screening experimental assessment of the seeds response of different agricultural crops to their pre-sowing treatment with nanoparticles of hydrothermal silica in a single scale of nanoparticle concentrations during dark laboratory germination.
MATERIALS AND RESEARCH METHODS
In accordance with the experimental work purpose the germination of 11 agricultural crop seeds (vegetables, oilseeds, fodder, medicinal), differing in biological characteristics, genetic nature, chemical and physicochemical composition and structure of seeds and their peels have been studied for various purposes. In total, 15 genotypes have been studied, including different species, varieties and hybrids.
Germination of seeds was carried out in the dark according to GOST 12038-84 "Seeds of agricultural crops. Methods for determining germination" and GOST 22617.2-94 "Sugar beet seeds. Methods for determining germination, monogermity and good quality" as amended: a mineral wool substrate was used instead of filter paper. Germination was carried out in a synergotron chamber – an experimental model of the IDS 1.01 model (developed by the Institute for Development Strategies). Watering was carried out with distilled water as the substrate dried up. Germination temperature was 23–24 °С and threefold repetition was applied.
Pre-sowing treatment with hydrothermal silica nanoparticles was carried out by soaking the seeds for 2 hours in distilled water (control) and in aqueous sols of hydrothermal nanosilica (HNS) of various concentrations (0.05%, 0.01%, 0.005%, 0.001%, and 0005%). Soybean seeds were an exception where soaking was carried out for 15 minutes. In the course of preliminary experiments it was found that a further increase in duration of soaking does not lead to an increase in the amount of the aqueous solution with the preparation absorbed by the seeds, while the integrity of soybean seeds is disturbed and they are easily injured during sowing.
For all experiments, we used the initial aqueous HNS sol of 37.5 wt. % concentration of SiO2 nanoparticles obtained by ultrafiltration methods at the Far Eastern Branch of the RAS, FSBSI "Research Geotechnological Center" (Petropavlovsk-Kamchatsky) in 2018 from the hydrothermal solution of the Mutnovskaya hydrothermal power plant wells according to the method described in [1–3].
A working aqueous sol of the HNS of 2.5% concentration was prepared in advance from the initial aqueous 37.5% HNS concentrate by diluting it with distilled water.
Before the start of each experiment with seeds of a specific agricultural crop, fresh aqueous sols of nanosilica were prepared out of a 2.5% working aqueous sol of HNS using distilled water of the indicated concentrations. The prepared aqueous HNS sols of various concentrations were used in experiments on pre-sowing treatment of seeds immediately after preparation for no more than 30 minutes.
Figure 1 shows a distribution of silica nanoparticles obtained using the dynamic light scattering method. The first peak corresponds to the maximum distribution of nanoparticles, the second peak is due to the formation of aggregates of nanoparticles in a dispersed nanosystem. The modal hydrodynamic diameter of the HNS particles of the initial concentrate and its 2.5% sol used in the work is 9 nm (measurements were carried out at the National Research Center "Kurchatov Institute").
According to GOST 12038-84, the germinative energy and seed germinating ability were determined in the following periods: meadow clover – on the 3rd day (germinative energy) and 7th day (germinating ability), coriander – on the 6th and 15th days, respectively, alfalfa changeable – on the 4th and 7th days, meadow fescue and festulolium – on days 5 and 10, bent grass – 7 and 14, rapeseed – 3 and 7, radishes – on 3 and 6, table beets – 5 and 10, soybeans – 3 and 7 days, respectively. Seeds of sugar beet were germinated according to GOST 22617.2-94 for 4 days to determine the germinative energy and for 10 days – to determine the germinating ability. As regards the new fodder culture of the Abyssinian nougat, the GOST for germinating ability has not yet been developed for germination, therefore, the sowing properties in the experiment were determined by analogy with other rapidly germinating seeds – on days 3 and 7.
Since the purpose of this work was to compare the effects of hydrothermal nanosilica on 11 agricultural crops, all data on the sowing properties of seeds were recalculated into relative values – the change (increase) in germinative energy and germinating ability in % relative to the control seeds of a particular crop (i.e. without HNS processing). Thus, it becomes possible to compare and analyze the data obtained in the experiment for different crops.
The germinating ability of the original seeds used in the experiment (control) ranged from 51.4% (clover, variety Mars) to 98.1% (radish, variety Yubileiny) for different crops; the germinative energy varied in a much wider range (Table 1). All data presented in section "Results and their discussion" are compared with the indicated controls in relative units (in %).
RESULTS AND THEIR DISCUSSION
The use of nanosized silica during seed germination in the experiment made it possible to increase the seed germinative energy by a maximum of 10.5% in comparison with the control (soybean, Alena variety). At the same time, for a number of crops, the increase in seed germinative energy did not exceed 1% (rapeseed, varieties Antares and Ratnik, alfalfa variety Selena, clover meadow, varieties Mars and Pavlovsky). A small level of increased germinating ability is characteristic of all studied rapeseed and clover varieties. At the same time, the increase in the germinating ability of seeds of alfalfa variety Selena was 0.6%, and that of alfalfa variety Pastbishchnaya 88 – 1.2%.
The germinating ability of seeds with the use of HNS increased by a maximum of 8.3% compared to the control (sugar beet, hybrid Smena F1). However, for the same crops, which showed a minimum increase in seed germinative energy, the increase in germinative ability was also minimal, and did not exceed 1% (rapeseed, varieties Antares and Ratnik, alfalfa, variety Selena, meadow clover, varieties Mars and Pavlovsky). At the same time, the increase in germinative ability of seeds of alfalfa, variety Selena, was 0.4%, and that of alfalfa, variety Pasturenaya 88 – 1.3%. For coriander, variety Yantar, the increase in germination energy was up to a maximum of 5.1%, and the increase in germination rate was up to 0.7%.
A significant increase in seed germinative energy under the influence of treatment with silica nanoparticles (to a greater extent than germinating ability) in the experiment was also manifested, except coriander, in a number of other crops, especially Abyssinsky nougat, Lipchanin variety, and soybean, Alena variety. At the same time, HNS can stimulate a greater increase in the germinating ability than the germinative energy indicator (for example, sugar beet, hybrid Smena F1, Festulolium, Allegro variety).
Thus, the genetic factor plays a significant role in the formation of plant response to the use of hydrothermal nanosilica during seed germination in the dark mode.
Screening of seeds of different crops and varieties according to the reaction of energy and germinating ability indicators to the treatment with HNS of different concentrations (0.05%, 0.01%, 0.005%, 0.001% and 0005%) showed existence of several types of such reactions. Figures 2–9 show four generalized groups of crops, differing in the geometric form of the response-display on the graph illustrating dependence of the energy indicator (germinating ability) to the control, depending on the concentration of HNS in the water sol during presowing seed treatment. Different plants were distributed among groups by visualizing these diagrams reflecting the response forms of the seeds of the corresponding crops. Selected for the analysis were those crops and varieties in which the increase in germinative energy and seed germinating ability, when using HNC, exceeded 1%. We note that the identified four types of reactions can be traced both in the analysis of the germinative energy and germinating ability, however, complete coincidence is not found. This is probably due to the fact that the totality of manifestations of biochemical (specificity and activity of enzymes), biophysical (structure of the seed), chemical (chemical composition of seed nutrients) and physiological factors (features of germination) form the characteristic signs of "germinative energy" and "germinating ability" on the diagrams, which adds significant differences (change the ranking of the significance of factors) along with the specificity of genomes. However, in crops with an increase in indicators of the germinating ability and germinative energy of less than 1%, similar tendencies were observed in the type of response-reaction (according to the type of group 1 in germination – in rapeseed, variety Antares, in group 2 – in germination – in rape, variety Ratnik, clover, variety Mars, coriander, variety Yantar, groups 3 – by germination energy – clover, variety Mars, by germination – by clover, variety Pavlovsky, group 4 – by germination energy – alfalfa, variety Selena, rape, variety Ratnik and rape, variety Antares, clover, Pavlovsky variety, by germination rate – in alfalfa, Selena variety).
Group 1. The maximum increase after use of HNS is observed in the area of low and moderate concentrations of nanoparticles in terms of germinative energy: radish (Yubileiny variety), Abyssinsky nougat (Lipchanin variety), soybean (Alena variety), festulolium (Allegro variety) – Fig.2, according to the germinating ability: sugar beet (hybrid Smena F1), festulolium (Allegro variety), soybean (Alena variety) – Fig.3.
Group 2. The maximum increase after use of HNS mainly in the range of high and moderately high concentrations of nanoparticles in terms of germinative energy: table beet (Demetra variety), coriander (Yantar variety) – Fig.4, according to the germinating ability: table beet (Demetra variety), fescue (Kvart variety) – Fig.5.
Group 3. The maximum increase is observed mainly in the area of average concentrations of HNS (typical examples of germinative energy: sugar beet (hybrid Smena F1), fescue (Kvart variety), bent grass (VIK-2 variety) – Fig.6. according to the germinating ability: bent VIC-2), alfalfa (Pasture 88 variety) – Fig.7.
Group 4. It is characterized by the presence of two pronounced maxima and minima of the germinative energy – alfalfa (Pastbishnaya 88 variety) – Fig.8, according to the germinating ability – Abyssinsky nougat (Lipchanin variety) and radish (Yubileiny variety) – Fig.9.
CONCLUSIONS
The use of hydrothermal nanosilica affects the level and direction of plant metabolism, which leads to a change in plant properties. It can be assumed that the mechanisms of the HNS effect on plants will differ in different periods of ontogenesis. In general, the question of the effect of nanosilica on the stage of seed germination is still poorly developed. In this work, for the first time, experimental data were obtained on assessing the effect of hydrothermal nanosilica of different concentrations (0.05%, 0.01%, 0.005%, 0.001% and 0.0005%) on seed germination of 11 (15 genotypes) agricultural plants differing in economic use, biological properties, biochemical composition and physicochemical structure of the seed.
Four types of reaction of dark germination of seeds to the effect of hydrothermal silica nanoparticles in the concentration range from 0.0005% to 0.05% have been established. These patterns are typical for both the "seed germinative energy" and "seed germinating ability" indicator, but they do not always coincide for the same crop. Thus, the genetic and epigenetic factors of the chemical, biochemical and physicochemical and biophysical (structure of specific seeds) plant composition play a significant role in the formation of the response of specific plant seeds to the effect of natural silica nanoparticles of various concentrations during pre-sowing seed treatment.
The data obtained in the study can be useful for understanding the mechanisms of the effect of nanoparticles at the stage of seed germination, as well as for subsequent use for the development of biotechnologies for pre-sowing seed treatment in the open and protected ground crop production, as well as for obtaining a new type of food products – seed sprouts and microgreens. ■
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