Report
Faculty of Biotechnology and Horticulture
Department of Botany, Physiology, and Plant Protection
PL 31-425 Kraków, Al. 29 Listopada 54
Phone: +48(12) 662 52 09; +48 (12) 662 52 57; Email: kbfior@urk.edu.pl
Correspondence Address: PL 31-120 Al. Mickiewicza 21

Prepared by: Dr. Eng. Iwona Kamińska
Kraków, 30-08-2024

Report on the progress of the research project titled: “Determining the effectiveness of disinfecting rooms with a UV-C radiation-emitting lamp (UVC Tower) from fungal contaminants, along with an assessment of plant tolerance to applied doses of UV-C radiation.

The study was commissioned by the company MacWarren Medical Sp. z o.o., located in Katowice, and carried out by a team from the Department of Botany, Physiology, and Plant Protection of the Faculty of Biotechnology and Horticulture at the Hugo Kołłątaj University of Agriculture in Kraków.

Introduction

The purpose of the study was to determine the effectiveness of UV-C radiation emitted by a Tower-type lamp (provided by MacWarren Medical Sp. z o.o.) in inhibiting the growth of mycelium of selected pathogenic fungi for plants, along with assessing plant tolerance to the applied doses of radiation.

UV-C radiation is one of the four long-wave regions of ultraviolet radiation. It is a high-energy ionizing radiation with a wavelength range of 200-280 nm, which does not naturally reach the Earth’s surface as it is effectively absorbed by the atmosphere. Research shows that UV-C radiation, emitted from specialized sources like fluorescent lamps, can be effectively used for disinfecting rooms and surfaces from bacterial contaminants. As researchers seek new applications for UV-C radiation and alternatives.

Methodology

The study was divided into two complementary parts:

1. Assessing the impact of three selected doses of UV-C radiation emitted by a portable lamp (model UVC Tower 800) on the growth of mycelial hyphae of pathogenic fungi for plants.
2. Assessing the tolerance level of selected plant species to varying doses of UV-C radiation emitted by the portable lamp (model UVC Tower 800).

Details on the preparation, conduct of the study, and data collection are provided below.

Part 1: Impact on the growth of mycelial hyphae of pathogenic fungi

The experimental material consisted of the following fungal species, known for their pathogenicity toward plants:

• Botrytis cinerea (gray mold),
• Fusarium oxysporum (causal agent of fusarium wilt),
• Penicillium expansum (a common postharvest pathogen).

Each fungal species was cultured on potato dextrose agar (PDA) medium in Petri dishes, and after mycelial growth initiation, the cultures were exposed to three doses of UV-C radiation:

• Low dose: 1 J/cm²,
• Medium dose: 3 J/cm²,
• High dose: 5 J/cm².

The UVC Tower 800 lamp was positioned at a distance of 1 meter from the samples. The duration of exposure was adjusted according to the desired dose. Post-irradiation, the cultures were incubated at 25°C, and fungal growth was assessed after 48 hours by measuring the diameter of the mycelial colonies.

Part 2: Assessment of plant tolerance to UV-C radiation

The following plant species were selected for the tolerance assessment:

• Solanum lycopersicum (tomato),
• Lactuca sativa (lettuce),
• Zea mays (maize).

Plants were grown in a controlled greenhouse environment and exposed to the same doses of UV-C radiation as applied in Part 1. The radiation was applied in two stages: initially at the seedling stage (2-3 weeks after germination) and again at the flowering stage for tomato and maize, and the bolting stage for lettuce.

Measurements of physiological responses were taken immediately post-irradiation and after a recovery period of 72 hours. These measurements included leaf chlorophyll content, visible injury symptoms, and growth rates (plant height and leaf area). Plants were monitored over a two-week period to evaluate potential delayed effects.

Results

Part 1: Fungal growth inhibition

The results demonstrated that UV-C radiation effectively inhibited the growth of all three fungal species. The degree of inhibition varied according to the dose of radiation. A low dose (1 J/cm²) significantly reduced mycelial growth of Botrytis cinerea, but had a lesser effect on Fusarium oxysporum and Penicillium expansum. Medium and high doses (3 J/cm² and 5 J/cm²) resulted in near-complete growth inhibition of all tested fungi. No fungal regrowth was observed after 7 days at the highest dose.

Part 2: Plant tolerance to UV-C radiation

Tomato, lettuce, and maize exhibited varying levels of tolerance to UV-C radiation. Lettuce showed the highest sensitivity, with noticeable chlorosis and leaf necrosis at the medium and high doses. Tomato and maize demonstrated moderate tolerance, though both species displayed minor leaf damage at the highest dose (5 J/cm²). However, all plants recovered from the low and medium doses, with no long-term adverse effects on growth observed after 14 days.

Discussion

The study confirmed the high efficacy of UV-C radiation in suppressing the growth of pathogenic fungi, making it a promising tool for disinfecting cultivation environments. The ability of UV-C to prevent fungal contamination, combined with the relatively high tolerance of common crop plants to moderate doses of UV-C, suggests that it could be effectively integrated into plant production systems, particularly in greenhouses.

However, the observed plant sensitivity, particularly in lettuce, indicates the need for careful dose management to avoid damaging crops. Future research should focus on optimizing the duration and intensity of UV-C exposure to balance effective disinfection with minimal impact on plant health.

Conclusion

The UV-C radiation emitted by the UVC Tower 800 lamp effectively inhibits the growth of pathogenic fungi such as Botrytis cinerea, Fusarium oxysporum, and Penicillium expansum. Additionally, plants like tomato and maize tolerate moderate doses of UV-C radiation well, though certain crops (e.g., lettuce) may require lower exposure levels to avoid damage. UV-C technology holds promise as a non-chemical method for disinfecting greenhouse environments, though further studies are needed to refine application protocols for different crops.