Makarenko N. The ecological role of silicon compounds in the increase of plant resistance to powdery mildew

The dissertation presents the results of the research synecological connections in the system "plant - phytopathogen - silicon compounds" for the defeat of powdery mildew pathogens. It was found that the use of silicon compounds leads to an acceleration of growth processes, promotes long-term flowering of plants, reduces the intensity of their defeat by powdery mildew and traces thickening of the upper epidermis cells and the cuticular layer of the leaves. The theory of reinforcement of cell structures by lignification and accumulation of silicon in integumentary tissues was confirmed. At first at the territory of the botanical garden during the anatomical study of the leaves of Monarda didyma was found a hyperparasite on the causative agent of powdery mildew, previously identified as Ampelomyces quisqualis Ces. Studying biochemical changes in when silicon compounds were applied in soil, there was found an increase of nitrogen, potassium, phosphorus, calcium, magnesium and iron in plant tissues. With the defeat by powdery mildew pathogens, the content of photosynthetic pigments in the leaves was 1,7–2,4 times lower than in plants grown in the presence of silicon compounds in soil. The concentration of chlorophylls and carotenoids changed significantly when plants were treated with chemical protection agents. The presence of silicon in soil substrate led to the accumulation of amino acids in plants, namely glutamic acid, proline, glycine, arginine, and histidine. In addition, the content of free alanine increased in the leaves, and, at the same time, the level of threonine and serine decreased. The dependence was also observed when analyzing the distribution of soluble carbohydrates in leaves. Calculation of the effectiveness of silicon compounds proved a positive effect, especially at 4‒6th months after application that led to an increase the resistance of plants to infection by powdery mildew pathogens.