For more than fifty years, experiments have been conducted on the use of lasers in agriculture. The study of laser light in interaction with biological material has taken place in various parts of the world and has provided evidence of the possibility of its use in agriculture. Scientific papers (1–4) have demonstrated the following findings: an increase in the energy potential of seeds (an increase in germination rate, germination percentage and germination energy, uniformity of germination and increased seed vitality), faster plant development, higher resistance to diseases, an effect on α-amylase activity and the concentration of free radicals in plant seeds that could deactivate their dormancy, as well as an effect on respiration, photosynthetic activity and the content of chlorophyll and carotenoids.

The effect of the laser as a monochromatic beam with a high density of light radiation can influence numerous photobiological processes in plants in connection with photosynthetic pigments and redox systems, from phytochrome to relationships with nucleic acids, enzymes and phytohormones. Laser irradiation has also proven to be active in relation to the formation of adventitious roots through its positive effect on the activity of endogenous phytohormones (5). Basic research has therefore already opened the way for operational application of promising laboratory results. Individual experiments, however,

Until now, attempts have encountered problems with practical feasibility, since it has not been possible to absorb the existing laboratory exposure into the seed within the required time and quality that would allow growers to achieve stable profit (uneven scanning of the laser beam, limited availability and power of lasers, etc.). A new hope for effective, practically usable laser stimulation has emerged in the form of the Fytolaser method (Fig. 1), which uses a highly variable device for a wide range of applications. It contains lasers of selected wavelengths and outputs, and optomechanics for distributing the laser radiation onto a layer of seed on a belt (Fig. 2). The chosen configuration uses scanning of the laser beam into a line by means of a rotating polygon, which enables the adjustment and distribution of the laser beam so that it covers the seed with high uniformity and the selected exposure dose. The intensity of the laser beam is adjusted using standard optics, and the exposure is set by the belt feed speed and the power of the laser beam. The method is backed by five years of positive results. Small-plot, semi-operational and operational tests indicate a breakthrough in the physical stimulation of seed, as it is an effective, cost-acceptable method with a rapid return on investment. 

Methodology

 Small-plot trials were carried out in the years 2020–2022 at the Field Experimental Station in Žabčice (Mendel University in Brno). The site, located in a maize-growing region, has an average annual temperature of 10.3 °C and an average annual precipitation total of 491.1 mm. In the first experimental year 2020, 7 variants were monitored in the trials, and in the years 2021–2022, 9 variants in three replications. In the stimulated variants, sugar beet seed was treated before sowing with a laser beam using the Fytolaser method. The variants differed in the wavelength of the laser used in the range of 532–650 nm, in the power of the laser used in the range of 0.2–1.0 W, and in the exposure time. A control variant without laser treatment was also included for comparison. The specific exposure values are available from the authors. The trial was conducted on the sugar beet variety BTS 555. Uniform pesticide treatment and identical fertilization were applied to all experimental plots. At the end of the growing season, selected yield and quality parameters were monitored (root yield, sugar content,

yield at 16% sugar content and white sugar yield), which were statistically evaluated using the Statistica 12 program. 

Results and discussion 

In 2020, the difference in root yield between the individual variants was not very pronounced (Tab. I). In some variants there was an increase in yield compared to the control variant, for example in variant 4, but the differences were not statistically significant. In the experimental year 2021, the conditions for sugar beet cultivation were better, so all variants achieved significantly higher root yields than in the previous year. In variant 5, which achieved the highest yield, the yield was statistically significantly higher compared to the control variant. In 2022, more statistically significant results were obtained, namely in variants 2, 3, 6, 7, 8, and 9. Given the differences in weather patterns in the individual monitored years, multi-year average yields were calculated, for which statistical significance was achieved in variant 9.

Another monitored parameter was sugar content. A positive effect of laser seed treatment was observed for this parameter in all treated variants, with an increase in sugar content compared to the control, including in the average of all experimental years (Tab. II).

An important parameter for the economics of sugar beet cultivation, both for growers and processors, is the yield recalculated to 16% sugar content (standard quality beet yield). This parameter combines the requirements for both yield and quality characteristics of the beet. In individual years, statistically significant differences were achieved in this parameter (Tab. III). On average over the tested years, variant 9 achieved the best result compared to the two-year average of the control variant (111.2%).

The evaluation also included the yield of white sugar (refined sugar). In 2020, there were no statistically significant differences for this parameter, although in variant 4 the sugar yield per hectare was 1 t higher compared to the control variant (Tab. IV). In the experimental year 2021, variants 4 and 5 achieved statistically significantly higher white sugar yields than the untreated control variant, and in the following year statistical significance was achieved 

more variants (Tab. IV). In the multi-year average, all variants achieved a significant increase in white sugar yield from 0.8 to 4.2 t·ha–1. Once again, variant 9 was the most statistically significant, reaching a white sugar yield of 112.5% compared to the control average (100%).

The positive effect of laser seed treatment on sugar content in roots is also confirmed by Sacała et al. (6) and Pulkrábek et al. (7), who observed in some exposures a similar increase in sugar content as was found in these trials. Likewise, Prośba-iałczyk et al. (8) confirm that laser irradiation of seed has a positive effect on sucrose content and helps reduce the content of molasses-forming substances in sugar beet roots. Pulkrábek et al. (7) state that the Fytolaser method helps increase root yield and consequently sugar yield. Operational results show that a significant effect is achieved under stress conditions in arid regions.

In 2023, a new three-year trial was established with new varieties that reflect breeding progress in disease resistance (BTS 17410 CR+) and in new technologies (BTS 9635 Smart). New types of lasers and their settings were selected for stimulation.

combination. The first harvest year confirmed the previously excellent results even under these new conditions. The results therefore confirm the positive effect of certain variants of laser seed stimulation on the yield parameters of sugar beet. Similar findings have also been reported in the past by other authors for various crops. The results of individual studies are difficult to compare due to different laser parameters, exposure times, etc., but all agree that laser seed stimulation positively influences the initial stages of plant development and stimulates the root system. Agrobiological monitoring of the semi-operational trials confirms these conclusions and objectively demonstrates higher root potential, higher chlorophyll content, larger leaf area, and the resulting higher intensity of photosynthesis with increased dry matter production (Tab. V).

Conclusion 

Laser stimulation of sugar beet seed can have a positive effect on growth, yield, and quality parameters. The effect depends on the parameters of the laser used and the exposure time. It was found that this method of seed preparation using the Fytolaser method positively influenced plant growth.  

The decline of the stand and growth during the vegetation period. This method is mainly applicable in arid areas. This article presents the results of small-plot field trials, but similar results were also obtained in semi-operational trials carried out on larger areas and on commercial fields of sugar beet growers, where the best treatments from the small-plot trials were used. 

References

 1. Ladjadjiyan, A.; Akanakova, D.: Physical methods in the agro-food chain. J. Cent. Eur. Agric., 9, 2008 (4), pp. 789–794.
2. Gładyszewska, B.: Presowing laser biostimulation of cereal grains. Tech. Sc., Pap. And Rep., 2006 (9), pp. 33–38.
3. Hernandez, A. C. et al.: Laser in agriculture. Int. Agrophys, 24, 2010, pp. 407–422.
4. Junlin, L.; Xuehon, G.; Heqi, Z.: Effect of laser pretreatment on germination and membrane lipid peroxidation of Chinese pine seeds under drought stress. Front. Biol. China, 2007 (3), pp. 314–317.
5. Šebánek, J., et al.: Growth and hormonal effects of laser on germination and rhizogenesis in plants. Přírodovědné práce ústavů ČSAV v Brně, 23, 1989 (9), pp. 49–69.
6. Sacała, E. et al.: Impact of presowing laser irradiation of seeds on sugar beet properties. Int. Agrophys., 26, 2012, pp. 295–300.
7. Pulkrábek, J. et al.: Effect of seed treatment with laser and starter fertilization on production indicators of sugar beet. In Osivo a sadba, XV. national professional and scientific seminar. Prague, 2021, pp. 148–152.
8. Prośba-Białczyk, U. et al.: Effect of seed stimulation on sugar beet productivity. Listy cukrov. řepař., 127, 2011 (11), pp. 344–347.
9. Białczyk, U. et al.: Effect of seed stimulation on germination and sugar beet yield. Int. Agrophys., 27, 2013, pp. 195–201.
10. Sacała, E. et al.: Effect of laser and hydropriming of seeds on some physiological parameters in sugar beet. J. Elem., 21, 2016 (2), pp. 527–538.
11. Osman, Y. A. H. et al.: Effect of laser radiation treatments on growth, yield and chemical constituents of fennel and coriander plants. J. App. Sci. Res., 5, 2009 (3), pp. 244–252.
12. Haan, J. et al.: Laser irradiation effects at different wavelengths on phenology and yield components of pretreated maize seed. Appl. Sci., 10, 2020 (1189), pp. 1–12.
13. Podleśna, A. et al.: Changes in the germination process and growth of pea as an effect of laser seed irradiation. Int. Agrophys., 2015, 29, pp. 485–492.

Academics on Laser Stimulation of Seeds

Prof. Dr. Ing. Jiří Šebánek, Dr.Sc 

 USE OF LASER TECHNOLOGY IN AGRICULTURE 

(Collection of Papers, Faculty of Agronomy, University of Agriculture Brno) 

"The effect of a laser as a monochromatic beam with a high density of light radiation can intervene in numerous photobiological processes in plants in connection with photosynthetic pigments and redox systems, through phytochrome, up to relationships with nucleic acids, enzymes and phytohormones." (Jiří Šebánek, 1985) GROWTH AND HORMONAL EFFECTS OF LASER ON GERMINATION AND RHIZOGENESIS IN PLANTS (Czechoslovak Academy of Sciences, Jiří Šebánek, Jan Králík, Mária Hudeová, Šárka Klíčová, 1989) - "Laser irradiation has also proved to be active in relation to the formation of adventitious roots through its positive effect on the activity of endogenous phytohormones." (Jiří Šebánek, 1989) - "It is undeniable that laser irradiation of seeds affects both enzymatic activity and the phytohormonal level in seedlings grown from laser-irradiated seeds. On this basis, it becomes possible to favorably influence seed germination and plant growth at the beginning of their development, as well as the chlorophyll content in leaves. The growth of adventitious roots could also be influenced by laser treatment." (Karel Římovský, 1989) 

Prof. Ing. Vladislav Čurn, Ph.D., Prof. RNDr. Petr Špatenka, CSc. 

 ALTERNATIVE METHODS OF SEED TREATMENT (Presentation – University of South Bohemia in České Budějovice) 

“The influence of physical and biological treatment of winter oilseed rape seed had a positive effect on germination energy and the rate of initial plant growth, overwintering, the number of branches per plant, the number and length of pods, and earliness (the onset of flowering and maturity was earlier in the treated variants). The positive effect was reflected in good crop development and, ultimately, in higher yield.” (V. Čurn, P. Špatenka, 2017) 

Prof. Ing. Josef Pulkrábek, CSc. 

SEED AND PLANTING MATERIAL (15th National, Professional and Scientific Seminar – Czech University of Life Sciences in Prague) 

"The one-year results presented confirm the data reported by other researchers that the FYTOLASER method helps increase the yield of beet roots and consequently sugar. Operational results show that a significant effect is achieved under stress conditions in arid regions." The effect of laser treatment of sugar beet seed also increased the yield of white sugar. (Josef Pulkrábek, 2021)