Assessment of spectral profiles of the leaf Quercus robur L. under normal conditions and with powdery mildew disease

At the present time technologies of comprehensive assessment of the vital state of plants without conducting labor-intensive laboratory researches are being developed and created. Such technology is the assessment of morphological, physiological and biochemical parameters of the leaf using spectroradiometry. One of the main woody plants used in forest plantations in the South of Russia is Quercus robur L., which is susceptible to such a phytopathogen Microsphaera alphitoides L., which causes such a disease as powdery mildew. In this regard, the purpose of the study was to evaluate the spectral profiles of the leaf of Quercus robur L. with normal health conditions and with powdery mildew disease. The spectral profiles of radiation transmission and absorption were obtained and assessed using a SpectraPen SP110 Uvis spectroradiometer. As a result of the study, it was shown that in Quercus robur L. individuals with powdery mildew, the observed radiation transmittance and absorption coefficients differ by 1.1-1.4 times compared to healthy plants. It is worth noting that in diseased plants, high absorption coefficients were recorded in the wavelength range from 400 nm to 520 nm compared to healthy Quercus robur L. individuals. These results suggest that the presence of powdery mildew on the leaf causes changes in its spectral parameters, which can be caused by increased activity of pigments and the production of phytopathogenic metabolites. In this regard, the assessment of transmission or absorption spectrograms may in the future make it possible to quickly detect infection with one or another phytopathogen that does not have a noticeable color at an early stage of growth and to assess the vital state of plants.