rus
Issue #3/2023
E. A. Sosnin, V. A. Panarin, V. S. Skakun, D. A. Sorokin, E. N. Surnina, I. A. Viktorova, L. V. Lyashcheva
The Influence of the Solar UVB Radiation Simulator on the Sowing Qualities of Seeds and the Productivity of Economically Valuable Plants
The Influence of the Solar UVB Radiation Simulator on the Sowing Qualities of Seeds and the Productivity of Economically Valuable Plants
DOI: 10.22184/1993-7296.FRos.2023.17.3.238.248
The article presents the results of long-term laboratory and field studies of the effect of UVB radiation on germination, growth and yield of economically valuable plants. The objects of research are cucumber, flax, carrot, wheat, buckwheat, eggplant, pine and thuja, potato tubers, apple seedlings and grape cuttings. The performed studies prove the hypothesis that it is necessary to use subdoses of UVB radiation to compensate for the lack of solar ultraviolet radiation when growing plants in greenhouses or northern latitudes of Russia. The place of the obtained results in the total volume of world research is determined. The designs of irradiators based on excilamps are described, which allow for the processing of seed material both in laboratory conditions and in the field. On the example of four-year field studies carried out on wheat, the practical applicability and prospects of the proposed treatment method in solving urgent problems of transition to a highly productive agricultural economy are proved.
The article presents the results of long-term laboratory and field studies of the effect of UVB radiation on germination, growth and yield of economically valuable plants. The objects of research are cucumber, flax, carrot, wheat, buckwheat, eggplant, pine and thuja, potato tubers, apple seedlings and grape cuttings. The performed studies prove the hypothesis that it is necessary to use subdoses of UVB radiation to compensate for the lack of solar ultraviolet radiation when growing plants in greenhouses or northern latitudes of Russia. The place of the obtained results in the total volume of world research is determined. The designs of irradiators based on excilamps are described, which allow for the processing of seed material both in laboratory conditions and in the field. On the example of four-year field studies carried out on wheat, the practical applicability and prospects of the proposed treatment method in solving urgent problems of transition to a highly productive agricultural economy are proved.
Теги: biophotonics economically valuable plants excilamp growth and development hormesis solar ultraviolet uvb radiation биофотоника гормезис рост и развитие солнечный ультрафиолет уфб-излучение хозяйственно-ценные растения эксилампа
The Influence of the Solar UVB Radiation Simulator on the Sowing Qualities of Seeds and the Productivity of Economically Valuable Plants
E. A. Sosnin 1, 2, V. A. Panarin 1, V. S. Skakun 1, D. A. Sorokin 1, E. N. Surnina 2, I. A. Viktorova 3, L. V. Lyashcheva 4
Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia
National Research Tomsk State University, Tomsk, Russia
Tomsk Agricultural Institute ‒ Branch of the Novosibirsk State Agrarian University, Novosibirsk, Russia
State Agrarian University of the Northern Trans-Urals, Tyumen, Russia
The article presents the results of long-term laboratory and field studies of the effect of UVB radiation on germination, growth and yield of economically valuable plants. The objects of research are cucumber, flax, carrot, wheat, buckwheat, eggplant, pine and thuja, potato tubers, apple seedlings and grape cuttings. The performed studies prove the hypothesis that it is necessary to use subdoses of UVB radiation to compensate for the lack of solar ultraviolet radiation when growing plants in greenhouses or northern latitudes of Russia. The place of the obtained results in the total volume of world research is determined. The designs of irradiators based on excilamps are described, which allow for the processing of seed material both in laboratory conditions and in the field. On the example of four-year field studies carried out on wheat, the practical applicability and prospects of the proposed treatment method in solving urgent problems of transition to a highly productive agricultural economy are proved.
Key words: biophotonics, hormesis, growth and development, solar ultraviolet, UVB radiation, economically valuable plants, excilamp
The article received on: 01.03. 2023
The article accepted on: 21.03. 2023
2023 marks the 20th anniversary of the beginning of research on the effect of UVB and UVC radiation from excilamps on plant development in the optical radiation laboratory of the Institute of High-Current Electronics of the Siberian Branch of Russian Academy of Sciences.
Excilamps are a generalizing name for a class of devices emitting narrow-band spontaneous ultraviolet (UV) and/or vacuum ultraviolet (VUV) radiation of excimer and exciplex molecules. The narrow-band spectrum of radiation and the comparative diversity in the design of excilamp-based irradiators make it possible to widely use such radiation sources to solve various scientific and practical problems (microelectronics, inactivation of viruses and bacteria, photochemistry, treatment of skin diseases) [1–4]. This article will provide a selective review of the results of studies of the effect of low-dose XeCl-excilamp radiation on the development of economically valuable plants obtained in cooperation with several academic organizations of the Russian Federation (with an emphasis on the results of the last few years).
Let’s explain the reason for choosing the specified radiation source and the low-dose irradiation mode for operation. Experts know that the effect of a particular stress factor on biological objects significantly depends both on the object itself and on the nature and dose of the active factor [6–8]. This phenomenon was called hormesis. Currently, it is defined as a two‒phase dose-effect relationship, in which subdoses of the active factor have a stimulating (positive) effect on a biological object, and high doses of the factor have an inhibitory effect. The foreign term “priming” has a similar meaning, but it is applied only to the seed material. In this case, priming can be carried out by both chemical and physical factors [9–11].
In our research cycle, B-type ultraviolet radiation (290 < λ < 320 nm) or UVB radiation was chosen as a priming factor. The hypothesis that this factor at certain doses should cause hormesis was first expressed by us in 2013 [12]. We assumed that under natural conditions of solar illumination of the Earth’s surface, the share of UVB radiation in the total radiant flux is on average no more than 1 to 10%, which depends on atmospheric conditions and solar activity [13, 14]. In fact, this means that the planet’s surface reaches a subdose of UVB radiation, which, as we have suggested, may play an important role in initiating germination and primary photoregulation of plant growth.
To verify this statement and simulate the solar edge of UV radiation, we used barrier discharge excilamps on XeCl* molecules (XeCl excilamps), the typical spectrum of which is shown in Fig. 1. It is a narrow band of radiation in the wavelength range λ ~ 290–320 nm (B → X transitions of XeCl* molecules) with a maximum of radiation at λ = 308 nm and a half-width band Δλ1/2 = 1.9 nm. The figure shows that this spectrum overlaps the short-wave edge of solar radiation, so the lamp can be used to compensate for the lack of this radiation when growing plants in greenhouses or northern latitudes, i. e. in conditions when this environmental factor is blocked for various reasons. In this sense, our hypothesis could further be called compensatory.
Several models of XeCl-excilamp-based irradiators have been developed for research. The first model (BD_P ‒ barrier discharge, portable) shown in Fig. 2 (a) is a portable irradiator in which the excilamp 1 is placed in the housing 2, and equipped with a reflector 3. The irradiator is powered by ~220 V mains, but later, for work at the State Agrarian University of the Northern Trans-Urals, Tyumen, a model of a lamp with autonomous, accumulator feeding was created. The lamp is cooled by external air using a fan located in the housing (Fig. 2a), which is enough for its stable operation. Such irradiator, as practice has shown, is convenient for conducting laboratory or field experiments where the volumes of the irradiated material are small.
Another model (BD_InI ‒ barrier discharge, inner irradiation) uses the possibilities of various design versions of excilamps. If in the model (a) the radiation is output from the coaxial excilamp bulb through a perforated external electrode, then in the model shown in Fig. 2 (b) the inner electrode is perforated and the outer one is reflective, so the radiation is concentrated in the inner cavity of the excilamp (see more details about the various designs of excilamps in [2, 3]). Thus, this model is characterized by increased productivity due to the fact that the irradiated seed material is located in close proximity to the inner walls of the excilamp, which almost completely removes radiation losses for transportation. The seed material is loaded into the funnel 5 and pushed by an auger 4 into the bulb. If in the model (a) the collection of subdose by seed material can take several minutes, then in then model (b) the processing time is reduced by an order of magnitude.
The model shown in Fig. 2c, designed for use in heavily dusty rooms, which is typical both for work in the field and in granaries (BD_DF ‒ barrier discharge, dust free). For this, both the excilamp 1 and the power supply are placed in a metal case, and the radiation is output through a quartz window 7. This ensures isolation of the irradiator elements from aggressive environmental influences. This model was used by us during both laboratory and field studies.
The typical length of the excilamps for models (a) and (c) was 10–12 cm, and for model (b) ‒ 43 cm. In the latter case, it also increased the performance of the installation. Models (a) and (c) provided the energy luminosity on the surface of the excilamps from 15 to 30 MW/cm2, and model (b) ‒ up to 120 MW/cm2, respectively, although these values could be adjusted during the experiments.
The first experimental verification of the compensatory hypothesis was carried out in 2005. For this purpose, 50‑day-old seedlings of Siberian cedar (Pinus sibirica Du Tour), Ayan spruce (Picea ajanensis Lindl. et Gord. (Fisch. ex Carr.)) and Kayander larches (Larix cajanderi Mayr (Worosch.)) grown in laboratory conditions. The choice of objects was determined by the different biology and ecology of these species. In addition, it is known that coniferous plants are characterized by increased resistance to UV radiation: conifers are most strongly affected by UV radiation in the north of the boreal zone and in the mountains, since in the spring the reflectivity of snow and ice can increase the dose of ultraviolet radiation absorbed by trees by almost two times [16]. Both XeCl and KrBr excilamps were used for irradiation. The latter was taken for comparison, providing a maximum of irradiation at l = 206 nm (a section of UV radiation). It was shown that in both cases, treatment with subdoses of 3.6 MJ/m‒2 was a stress factor for the pigment fund of the photosynthetic apparatus of plants. However, UVB radiation stimulated the synthesis of chlorophyll in the leaves [17]. This indicated the manifestation of the photoregulatory effect of narrow-band UVB radiation, confirming the possibility of increasing plant productivity.
Based on the data obtained, it was decided to continue the research, for which in different years specialists from National Research Tomsk State University (Tomsk), Tomsk Agricultural Institute ‒ a Branch of Novosibirsk Agricultural University (Tomsk) and the State Agricultural University of the North Trans-Urals were involved. The main results obtained from 2014 to 2022 are summarized in the table. In most cases, UVB radiation treatment was single and applied to the seed material before planting. Laboratory and field studies were carried out, including greenhouse cultivation in protected soil. In some experiments, pre-sowing seed treatment was supplemented with the use of drugs that stimulate the growth of vegetative plants or bio-insecticides.
It can be seen that the experimental test confirmed the validity of the compensatory hypothesis in application to seeds of various crops (flax, cucumbers, wheat, lettuce, cedar, eggplant, thuja), to seedlings and cuttings (grapes, apple trees) and tubers (potatoes) of plants [18–28].
Since the 2010s, similar results for pre-sowing priming of seeds with UV radiation have been obtained abroad (see [8, 29]). Let’s compare these results with the ones we received.
Foreign studies have revealed hormesis in relation to economically valuable plants that are not cultivated in the middle latitudes of the Russian Federation or are not cultivated at all (rice, maize, soybeans, beans, groundnut, bitter pumpkin, etc.). Our data are obtained for varieties common in Siberia and beyond the Urals, in areas where there is an objective shortage of solar ultraviolet radiation even in the spring.
The processing of seed material in foreign studies was carried out using known radiation sources, such as:
Fluorescent mercury lamps with a maximum at λ = 312 nm (TL40W/12, Philips, Netherlands);
Germicidal lamps (30W LF‒215 M, Philips, France; TUV 15W G158T8, Netherlands; G30T8 lamps, General Electric, USA);
Gucun solar lamps (Gucun Instrument Factory, China);
XeCl excilamps were used in only one case (Beijing Electronic Resource Inc., China).
Despite the revealed beneficial effect of subdose irradiation, these sources have their drawbacks. The main disadvantage of lamps from groups (1) and (2) is the presence of mercury in the bulbs. Taking into account the gradually introduced bans on the production of mercury-containing lamps, it becomes risky to talk about their widespread introduction in the future. In addition, the surface of the lamps from group (2) was additionally covered with a filter layer of diacetate cellulose, which complicates the manufacture and operation of lamps. Solar lamps from group (3) gave the expected 6 results, but since the proportion of UVB radiation in their spectrum was small, the beneficial effect was achieved only after 7 hours of irradiation, which indicates high energy costs for processing.
In addition, the cited articles do not discuss the creation of technological irradiation installations taking into account the requirements for operating conditions. Group (4) is represented by only two articles [30, 31], and the tasks solved here are directly opposite to those that are relevant for the middle latitudes of the Russian Federation. In particular, it is shown here that the planting of ordinary varieties of buckwheat in the highlands of China (Qinghai-Tibet plateau) is associated with an increase in the level of UVB radiation and reduces the morphophysiological parameters of plants. In our conditions (lack of solar radiation) these studies are not relevant.
There is no confirmation of the processability of the actions taken by the authors in the described articles. In the Russian Federation, for this purpose, it is necessary to conduct field studies for three years in field (or greenhouse) conditions in order to prove the reproducibility of the useful effect of a particular processing method.
We have performed such a study in recent years on the basis of the Educational and Experimental site of the Siberian Botanic Garden of the National Research Tomsk State University (Tomsk) [32]. The object of the study was the seeds of soft spring wheat (Triticum aestivum L.) of the Iren variety. Before sowing, the seeds were once treated with XeCl excilamp radiation (BD_P model, Fig. 2 (a)) at doses of 0.5 and 0.25 J / cm2, and a dose of 0.5 J / cm2 was found by us earlier, in previous laboratory tests [21, 22]. A single seed treatment led to an increase in morphometric indicators (plant height, weight of the aboveground part, the area of the assimilating surface of the leaves), and wheat yield under the influence of subdoses of UVB irradiation increased by an average of 11.5% over four years of field research without causing a decrease in grain quality. Switching to reduced doses (0.25 J / cm2) of irradiation intensifies plant development and does not reduce crop yield (within the measurement error). From a scientific point of view, the facts found confirm the phenomenon of hormesis in our case. On the practical side, these facts should be taken into account when designing equipment for pre-sowing seed treatment.
Based on the found facts and comparative analysis, we predict at least two trends in the direction of biophotonics that we are developing:
We can expect a further extension of the list of economically valuable plants, the UVB treatment of which will accelerate their growth and development, increase resistance to stress and increase yields.
At the next stage of research, the issue of technical support of the treatment process should be resolved. In particular, to develop and test installations for large-tonnage treatment, as well as to perform comparative tests of LED and excilamp irradiation installations, and to choose the most appropriate equipment for operation “on the ground”.
All that has been said in our review allows us to confidently speak about the prospects of using UVB-band excilamps for pre-sowing preparation of seed material in zones of risky agriculture and northern regions of the Russian Federation. The seeds of this approach were planted a quarter of a century ago.
The work was carried out within the framework of the State Task of the Institute of High-Current Electronics, Siberian Branch of Russian Academy of Sciences, project No. FWRM‑2021-0014.
AUTHORS
Eduard Anatolievich Sosnin, Doctor of Physical and Mathematical Sciences, Leading Researcher at the Institute of High-Current Electronics, Siberian Branch of Russian Academy of Sciences, Professor at the Faculty of Innovative Technologies of the National Research Tomsk State University, Institute of High-Current Electronics, Siberian Branch of Russian Academy of Sciences, Tomsk, Russia.
Research interests: photonics, gas discharge physics, methodology of science, R&D management, patent science, system analysis, university studies, psychology of creativity, heuristics.
ORCID: 0000-0003-4728-8884
Viktor Aleksandrovich Panarin, Candidate of Physical and Mathematical Sciences, Researcher, Institute of High-Current Electronics, Siberian Branch of Russian Academy of Sciences, Tomsk, Russia.
Research interests: barrier discharge, photonics, gas discharge physics, pulsed high-voltage discharge.
ORCID: 0000-0002-3357-0187
Viktor Semenovich Skakun, Candidate of Physical and Mathematical Sciences, Senior Researcher, Institute of High-Current Electronics, Siberian Branch of Russian Academy of Sciences, Tomsk, Russia.
Research interests: photonics, gas discharge physics, laser technology.
ORCID: 0000-0001-7046-8563
Dmitry Alekseevich Sorokin, Candidate of Physical and Mathematical Sciences, Head of the Laboratory, Leading Researcher, Institute of High-Current Electronics, Siberian Branch of Russian Academy of Sciences, Associate Professor of the Department of Plasma Physics, Faculty of Physics, National Research Tomsk State University, Tomsk, Russia.
Research interests: optics, gas discharge physics, plasma physics.
ORCID: 0000-0002-6884-2525
Elena Nikolaevna Surnina, Senior Lecturer of the Department of Agricultural Biology of the Biological Institute of Tomsk State University, postgraduate student. National Research Tomsk State University, Tomsk, Russia.
Research interests: agricultural biology, plant growth and development; regulation of the production process of economically valuable crops by various factors (photoregulation, radiation and ultraviolet radiation, growth stimulators).
ORCID: 0000-0002-2455-8282,
Irina Aleksandrovna Viktorova, Candidate of Agricultural Sciences, Associate Professor, Associate Professor of the Department of Agronomy and Technology of Production and Processing of Agricultural Products, Tomsk Agricultural Institute - Branch of the Novosibirsk State Agrarian University, Tomsk Region, Tomsk, Russia.
Research interests: decorative gardening, vegetable growing, plant growing, horticulture, technology of storage and processing of plant products.
scopus id 57202450825.
Lyudmila Vasilyevna Lyashcheva, Doctor of Agricultural Sciences, Professor of the Department of General Biology of the Agrotechnological Institute, State Agrarian University of the Northern Trans-Urals, Tyumen Region, Tyumen, Russia.
Research interests: agrochemistry, plant growth regulators, ecology, fruit growing, vegetable growing, decorative dendrology.
ORCID: 0000-0002-9266-8707
E. A. Sosnin 1, 2, V. A. Panarin 1, V. S. Skakun 1, D. A. Sorokin 1, E. N. Surnina 2, I. A. Viktorova 3, L. V. Lyashcheva 4
Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia
National Research Tomsk State University, Tomsk, Russia
Tomsk Agricultural Institute ‒ Branch of the Novosibirsk State Agrarian University, Novosibirsk, Russia
State Agrarian University of the Northern Trans-Urals, Tyumen, Russia
The article presents the results of long-term laboratory and field studies of the effect of UVB radiation on germination, growth and yield of economically valuable plants. The objects of research are cucumber, flax, carrot, wheat, buckwheat, eggplant, pine and thuja, potato tubers, apple seedlings and grape cuttings. The performed studies prove the hypothesis that it is necessary to use subdoses of UVB radiation to compensate for the lack of solar ultraviolet radiation when growing plants in greenhouses or northern latitudes of Russia. The place of the obtained results in the total volume of world research is determined. The designs of irradiators based on excilamps are described, which allow for the processing of seed material both in laboratory conditions and in the field. On the example of four-year field studies carried out on wheat, the practical applicability and prospects of the proposed treatment method in solving urgent problems of transition to a highly productive agricultural economy are proved.
Key words: biophotonics, hormesis, growth and development, solar ultraviolet, UVB radiation, economically valuable plants, excilamp
The article received on: 01.03. 2023
The article accepted on: 21.03. 2023
2023 marks the 20th anniversary of the beginning of research on the effect of UVB and UVC radiation from excilamps on plant development in the optical radiation laboratory of the Institute of High-Current Electronics of the Siberian Branch of Russian Academy of Sciences.
Excilamps are a generalizing name for a class of devices emitting narrow-band spontaneous ultraviolet (UV) and/or vacuum ultraviolet (VUV) radiation of excimer and exciplex molecules. The narrow-band spectrum of radiation and the comparative diversity in the design of excilamp-based irradiators make it possible to widely use such radiation sources to solve various scientific and practical problems (microelectronics, inactivation of viruses and bacteria, photochemistry, treatment of skin diseases) [1–4]. This article will provide a selective review of the results of studies of the effect of low-dose XeCl-excilamp radiation on the development of economically valuable plants obtained in cooperation with several academic organizations of the Russian Federation (with an emphasis on the results of the last few years).
Let’s explain the reason for choosing the specified radiation source and the low-dose irradiation mode for operation. Experts know that the effect of a particular stress factor on biological objects significantly depends both on the object itself and on the nature and dose of the active factor [6–8]. This phenomenon was called hormesis. Currently, it is defined as a two‒phase dose-effect relationship, in which subdoses of the active factor have a stimulating (positive) effect on a biological object, and high doses of the factor have an inhibitory effect. The foreign term “priming” has a similar meaning, but it is applied only to the seed material. In this case, priming can be carried out by both chemical and physical factors [9–11].
In our research cycle, B-type ultraviolet radiation (290 < λ < 320 nm) or UVB radiation was chosen as a priming factor. The hypothesis that this factor at certain doses should cause hormesis was first expressed by us in 2013 [12]. We assumed that under natural conditions of solar illumination of the Earth’s surface, the share of UVB radiation in the total radiant flux is on average no more than 1 to 10%, which depends on atmospheric conditions and solar activity [13, 14]. In fact, this means that the planet’s surface reaches a subdose of UVB radiation, which, as we have suggested, may play an important role in initiating germination and primary photoregulation of plant growth.
To verify this statement and simulate the solar edge of UV radiation, we used barrier discharge excilamps on XeCl* molecules (XeCl excilamps), the typical spectrum of which is shown in Fig. 1. It is a narrow band of radiation in the wavelength range λ ~ 290–320 nm (B → X transitions of XeCl* molecules) with a maximum of radiation at λ = 308 nm and a half-width band Δλ1/2 = 1.9 nm. The figure shows that this spectrum overlaps the short-wave edge of solar radiation, so the lamp can be used to compensate for the lack of this radiation when growing plants in greenhouses or northern latitudes, i. e. in conditions when this environmental factor is blocked for various reasons. In this sense, our hypothesis could further be called compensatory.
Several models of XeCl-excilamp-based irradiators have been developed for research. The first model (BD_P ‒ barrier discharge, portable) shown in Fig. 2 (a) is a portable irradiator in which the excilamp 1 is placed in the housing 2, and equipped with a reflector 3. The irradiator is powered by ~220 V mains, but later, for work at the State Agrarian University of the Northern Trans-Urals, Tyumen, a model of a lamp with autonomous, accumulator feeding was created. The lamp is cooled by external air using a fan located in the housing (Fig. 2a), which is enough for its stable operation. Such irradiator, as practice has shown, is convenient for conducting laboratory or field experiments where the volumes of the irradiated material are small.
Another model (BD_InI ‒ barrier discharge, inner irradiation) uses the possibilities of various design versions of excilamps. If in the model (a) the radiation is output from the coaxial excilamp bulb through a perforated external electrode, then in the model shown in Fig. 2 (b) the inner electrode is perforated and the outer one is reflective, so the radiation is concentrated in the inner cavity of the excilamp (see more details about the various designs of excilamps in [2, 3]). Thus, this model is characterized by increased productivity due to the fact that the irradiated seed material is located in close proximity to the inner walls of the excilamp, which almost completely removes radiation losses for transportation. The seed material is loaded into the funnel 5 and pushed by an auger 4 into the bulb. If in the model (a) the collection of subdose by seed material can take several minutes, then in then model (b) the processing time is reduced by an order of magnitude.
The model shown in Fig. 2c, designed for use in heavily dusty rooms, which is typical both for work in the field and in granaries (BD_DF ‒ barrier discharge, dust free). For this, both the excilamp 1 and the power supply are placed in a metal case, and the radiation is output through a quartz window 7. This ensures isolation of the irradiator elements from aggressive environmental influences. This model was used by us during both laboratory and field studies.
The typical length of the excilamps for models (a) and (c) was 10–12 cm, and for model (b) ‒ 43 cm. In the latter case, it also increased the performance of the installation. Models (a) and (c) provided the energy luminosity on the surface of the excilamps from 15 to 30 MW/cm2, and model (b) ‒ up to 120 MW/cm2, respectively, although these values could be adjusted during the experiments.
The first experimental verification of the compensatory hypothesis was carried out in 2005. For this purpose, 50‑day-old seedlings of Siberian cedar (Pinus sibirica Du Tour), Ayan spruce (Picea ajanensis Lindl. et Gord. (Fisch. ex Carr.)) and Kayander larches (Larix cajanderi Mayr (Worosch.)) grown in laboratory conditions. The choice of objects was determined by the different biology and ecology of these species. In addition, it is known that coniferous plants are characterized by increased resistance to UV radiation: conifers are most strongly affected by UV radiation in the north of the boreal zone and in the mountains, since in the spring the reflectivity of snow and ice can increase the dose of ultraviolet radiation absorbed by trees by almost two times [16]. Both XeCl and KrBr excilamps were used for irradiation. The latter was taken for comparison, providing a maximum of irradiation at l = 206 nm (a section of UV radiation). It was shown that in both cases, treatment with subdoses of 3.6 MJ/m‒2 was a stress factor for the pigment fund of the photosynthetic apparatus of plants. However, UVB radiation stimulated the synthesis of chlorophyll in the leaves [17]. This indicated the manifestation of the photoregulatory effect of narrow-band UVB radiation, confirming the possibility of increasing plant productivity.
Based on the data obtained, it was decided to continue the research, for which in different years specialists from National Research Tomsk State University (Tomsk), Tomsk Agricultural Institute ‒ a Branch of Novosibirsk Agricultural University (Tomsk) and the State Agricultural University of the North Trans-Urals were involved. The main results obtained from 2014 to 2022 are summarized in the table. In most cases, UVB radiation treatment was single and applied to the seed material before planting. Laboratory and field studies were carried out, including greenhouse cultivation in protected soil. In some experiments, pre-sowing seed treatment was supplemented with the use of drugs that stimulate the growth of vegetative plants or bio-insecticides.
It can be seen that the experimental test confirmed the validity of the compensatory hypothesis in application to seeds of various crops (flax, cucumbers, wheat, lettuce, cedar, eggplant, thuja), to seedlings and cuttings (grapes, apple trees) and tubers (potatoes) of plants [18–28].
Since the 2010s, similar results for pre-sowing priming of seeds with UV radiation have been obtained abroad (see [8, 29]). Let’s compare these results with the ones we received.
Foreign studies have revealed hormesis in relation to economically valuable plants that are not cultivated in the middle latitudes of the Russian Federation or are not cultivated at all (rice, maize, soybeans, beans, groundnut, bitter pumpkin, etc.). Our data are obtained for varieties common in Siberia and beyond the Urals, in areas where there is an objective shortage of solar ultraviolet radiation even in the spring.
The processing of seed material in foreign studies was carried out using known radiation sources, such as:
Fluorescent mercury lamps with a maximum at λ = 312 nm (TL40W/12, Philips, Netherlands);
Germicidal lamps (30W LF‒215 M, Philips, France; TUV 15W G158T8, Netherlands; G30T8 lamps, General Electric, USA);
Gucun solar lamps (Gucun Instrument Factory, China);
XeCl excilamps were used in only one case (Beijing Electronic Resource Inc., China).
Despite the revealed beneficial effect of subdose irradiation, these sources have their drawbacks. The main disadvantage of lamps from groups (1) and (2) is the presence of mercury in the bulbs. Taking into account the gradually introduced bans on the production of mercury-containing lamps, it becomes risky to talk about their widespread introduction in the future. In addition, the surface of the lamps from group (2) was additionally covered with a filter layer of diacetate cellulose, which complicates the manufacture and operation of lamps. Solar lamps from group (3) gave the expected 6 results, but since the proportion of UVB radiation in their spectrum was small, the beneficial effect was achieved only after 7 hours of irradiation, which indicates high energy costs for processing.
In addition, the cited articles do not discuss the creation of technological irradiation installations taking into account the requirements for operating conditions. Group (4) is represented by only two articles [30, 31], and the tasks solved here are directly opposite to those that are relevant for the middle latitudes of the Russian Federation. In particular, it is shown here that the planting of ordinary varieties of buckwheat in the highlands of China (Qinghai-Tibet plateau) is associated with an increase in the level of UVB radiation and reduces the morphophysiological parameters of plants. In our conditions (lack of solar radiation) these studies are not relevant.
There is no confirmation of the processability of the actions taken by the authors in the described articles. In the Russian Federation, for this purpose, it is necessary to conduct field studies for three years in field (or greenhouse) conditions in order to prove the reproducibility of the useful effect of a particular processing method.
We have performed such a study in recent years on the basis of the Educational and Experimental site of the Siberian Botanic Garden of the National Research Tomsk State University (Tomsk) [32]. The object of the study was the seeds of soft spring wheat (Triticum aestivum L.) of the Iren variety. Before sowing, the seeds were once treated with XeCl excilamp radiation (BD_P model, Fig. 2 (a)) at doses of 0.5 and 0.25 J / cm2, and a dose of 0.5 J / cm2 was found by us earlier, in previous laboratory tests [21, 22]. A single seed treatment led to an increase in morphometric indicators (plant height, weight of the aboveground part, the area of the assimilating surface of the leaves), and wheat yield under the influence of subdoses of UVB irradiation increased by an average of 11.5% over four years of field research without causing a decrease in grain quality. Switching to reduced doses (0.25 J / cm2) of irradiation intensifies plant development and does not reduce crop yield (within the measurement error). From a scientific point of view, the facts found confirm the phenomenon of hormesis in our case. On the practical side, these facts should be taken into account when designing equipment for pre-sowing seed treatment.
Based on the found facts and comparative analysis, we predict at least two trends in the direction of biophotonics that we are developing:
We can expect a further extension of the list of economically valuable plants, the UVB treatment of which will accelerate their growth and development, increase resistance to stress and increase yields.
At the next stage of research, the issue of technical support of the treatment process should be resolved. In particular, to develop and test installations for large-tonnage treatment, as well as to perform comparative tests of LED and excilamp irradiation installations, and to choose the most appropriate equipment for operation “on the ground”.
All that has been said in our review allows us to confidently speak about the prospects of using UVB-band excilamps for pre-sowing preparation of seed material in zones of risky agriculture and northern regions of the Russian Federation. The seeds of this approach were planted a quarter of a century ago.
The work was carried out within the framework of the State Task of the Institute of High-Current Electronics, Siberian Branch of Russian Academy of Sciences, project No. FWRM‑2021-0014.
AUTHORS
Eduard Anatolievich Sosnin, Doctor of Physical and Mathematical Sciences, Leading Researcher at the Institute of High-Current Electronics, Siberian Branch of Russian Academy of Sciences, Professor at the Faculty of Innovative Technologies of the National Research Tomsk State University, Institute of High-Current Electronics, Siberian Branch of Russian Academy of Sciences, Tomsk, Russia.
Research interests: photonics, gas discharge physics, methodology of science, R&D management, patent science, system analysis, university studies, psychology of creativity, heuristics.
ORCID: 0000-0003-4728-8884
Viktor Aleksandrovich Panarin, Candidate of Physical and Mathematical Sciences, Researcher, Institute of High-Current Electronics, Siberian Branch of Russian Academy of Sciences, Tomsk, Russia.
Research interests: barrier discharge, photonics, gas discharge physics, pulsed high-voltage discharge.
ORCID: 0000-0002-3357-0187
Viktor Semenovich Skakun, Candidate of Physical and Mathematical Sciences, Senior Researcher, Institute of High-Current Electronics, Siberian Branch of Russian Academy of Sciences, Tomsk, Russia.
Research interests: photonics, gas discharge physics, laser technology.
ORCID: 0000-0001-7046-8563
Dmitry Alekseevich Sorokin, Candidate of Physical and Mathematical Sciences, Head of the Laboratory, Leading Researcher, Institute of High-Current Electronics, Siberian Branch of Russian Academy of Sciences, Associate Professor of the Department of Plasma Physics, Faculty of Physics, National Research Tomsk State University, Tomsk, Russia.
Research interests: optics, gas discharge physics, plasma physics.
ORCID: 0000-0002-6884-2525
Elena Nikolaevna Surnina, Senior Lecturer of the Department of Agricultural Biology of the Biological Institute of Tomsk State University, postgraduate student. National Research Tomsk State University, Tomsk, Russia.
Research interests: agricultural biology, plant growth and development; regulation of the production process of economically valuable crops by various factors (photoregulation, radiation and ultraviolet radiation, growth stimulators).
ORCID: 0000-0002-2455-8282,
Irina Aleksandrovna Viktorova, Candidate of Agricultural Sciences, Associate Professor, Associate Professor of the Department of Agronomy and Technology of Production and Processing of Agricultural Products, Tomsk Agricultural Institute - Branch of the Novosibirsk State Agrarian University, Tomsk Region, Tomsk, Russia.
Research interests: decorative gardening, vegetable growing, plant growing, horticulture, technology of storage and processing of plant products.
scopus id 57202450825.
Lyudmila Vasilyevna Lyashcheva, Doctor of Agricultural Sciences, Professor of the Department of General Biology of the Agrotechnological Institute, State Agrarian University of the Northern Trans-Urals, Tyumen Region, Tyumen, Russia.
Research interests: agrochemistry, plant growth regulators, ecology, fruit growing, vegetable growing, decorative dendrology.
ORCID: 0000-0002-9266-8707
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