Impact of Ozone Exposure on Chlorophyll Fluorescence, Pigment Content and Leaf Gas Exchange on Lonicera caerulea var. kamtschatica and Lonicera caerulea var. emphyllocalyx

Lonicera caerulea is a species known for its fruit with a rich health-promoting composition and the high frost resistance of its bushes. The increase in the popularity of this species and the number and area of plantations increases the risk of diseases and pests. However, the use of ozone gas may involve the risk of physiological damage to the plant. In this experiment, in 2022–2023, the physiological response of six varieties of Lonicera caerulea L. to gaseous ozone at a concentration of 5 ppm·1 min, 5 ppm·3 min and 5 ppm·5 min was determined. The flavonoid–nitrogen index (NFI) remained unchanged at 0.33 in both non-ozonated leaves and those exposed to a 5 ppm·3 min dose of ozone. In general, ozonation did not lead to significant changes in the physiological parameters observed for most of the varieties studied. The mean performance index (P itotal) value of the ozonated leaves decreased by 23.1% for LE ‘Lori’ and 23.8% for ‘139-24’, after applying an ozone dose of 5 ppm·5 min in 2022. A significant decrease of 34.3% in the average transpiration rate (E) was observed after the use of 5 ppm·5 min ozone in plants of the variety ‘21-17’ across both years of cultivation. The different effects of the ozone doses used may indicate different reactions depending on the variety used and the year of cultivation. Overall, the study found that ozone does not have a phytotoxic effect on most varieties, which may indicate different reactions and differences between varieties. The use of an appropriate dose of ozone did not cause any disruption in the selected physiological parameters of Lonicera caerulea L. plants. The absence of phytotoxicity in some varieties may allow the use of ozonation treatments in agriculture; however, further research on the long-term effects on plants is required.