Characteristics of powdery mildew [Sawadaea bicornis (Wallr.) Miyabe] influence on the photosynthetic process in Norway maple (Acer platanoides L.) seedlings

The article presents the results of research on the impact of Sawadaea bicornis (Wallr.) Miyabe on the state of photosynthetic apparatus in Acer platanoides L. seedlings using a technique of chlorophyll fluorescence induction (ChlF) measurement, which at the present time can be implemented through the use of biosensors. The research was conducted in September 2022 in the territory of the Botanical Garden of Oles Honchar Dnipro National University. To diagnose a violation of the native chlorophyll photosynthesis in fresh leaves of A. platanoides, a portable fluorometer 'Floratest' was used (the selected spectral range for fluorescence intensity measurement was 670-800 nm). The research was carried out on fresh leaves of Norway maple seedlings both not unaffected and affected with powdery mildew. Analysis of the data obtained indicates a high sensitivity of the parameters of chlorophyll fluorescence induction to damage by the disease regardless of environmental conditions of local growth of A. platanoides seedlings. The high informativeness of induction changes in chlorophyll fluorescence in the structural organisation of chloroplasts in Norway maple leaves determined by the parameters Fo, Fm, Fv, Fv/Fо, Fv/Fm, (Fm - Fst)/Fst, (Fp - Fо)/Fv was revealed. This study demonstrated the effectiveness of using the studied chlorophyll fluorescence parameters to detect severe stress in Norway maple seedlings caused by powdery mildew exposure when the fungus affects more than 50% of the leaf blade area. It is further necessary to conduct dynamic studies throughout the growing season to determine the effectiveness of using these parameters to detect mild stress in the early stages of infection.