Effect of fungicides on the enzymatic activity of the antioxidant system and the chlorophyll content in lupine plants during seed dressing

Goal. The effect of fungicides on the dynamics of the activity of peroxidase, catalase (CAT) and chlorophyll content in lupine plants during seed dressing has been established. Methods. Laboratory and vegetation researches were conducted in the laboratory of analytical chemistry of pesticides of the Institute of Plant Protection. Yellow lupine (Lupinus luteus L.), variety Obriy has been grown. The objects of research were fungicides triticonazol (40 g/t) and its combination with prochloraz (120 g/t). Determination of the content of fungicides in plants was carried out using chromatographic methods according to officially approved methods and me­thods developed in the laboratory of analytical chemistry of pesticides. Chlorophyll content and peroxidase activity were measured by colorimetric method, catalase activity — by titrimetric method. Results. According to the research results, the varying sensitivity of the enzymatic system of antioxidant defense (catalase, peroxidase) in response to seed dressing by fungicides was recorded. It showed that on the 10th day after sowing, content of triticonazol in plants was 0.8 mg/kg, and the peroxidase activity was similar to that in untreated plants. Subsequently, against the background of a decrease in the content of the active substance, a gradual activation of the enzyme was observed. Catalase activity also gradually increased beginning from the 14th day, and on the 30th day it exceeded the corresponding control indicator by 40%. When using a combination of triticonazol with prochloraz, the disturbance in the balance of peroxidase catalase was more significant. However, by the phase of 7—8 leaves, with a minimal total content of fungicides (0.38 mg/kg), the enzyme activity approached the control level, which is associated with the restoration of plant homeostasis and the formation of its adaptive potential under stress conditions. The stimulating effect of these fungicides on chlorophyll content at the initial growth stages of lupine was established. The chlorophyll concentration in fungicides-treated plants exceeded the control indicator by 11—29%. Conclusions. The use of systemic triazole fungicides to protect seedlings, improves the photosynthetic activity of plants and at the same time acts as a stress factor that activates protecting enzymes (catalase, peroxidase), which trigger the development of protective adaptive reactions of plants.