Effect of temperature and culture media on Sclerotinia sclerotiorum mycelial growth and sclerotia formation

Goal. To determine the optimal nutrient media for cultivating the white rot pathogen and stimulating the formation of sclerotia. Methods. The growth dynamics of Sclerotinia sclerotiorum and the process of sclerotia formation were studied in vitro under the combined influence of two factors: temperature and nutrient media of different composition. Results. Significant differences were found in the rate of mycelial growth and sclerotia formation depending on the medium and temperature. The highest radial growth rate was observed on potato-dextrose agar and nutrient agar at temperatures of 20 and 25°C — 14.2 mm/day, the lowest — on V8 medium over the entire range of studied temperatures. The maximum formation of sclerotia (25 pcs./plate with an average mass of 15 mg) was recorded when cultivating on potato-dextrose agar at a temperature of 20°C. Increasing and decreasing the temperature led to a decrease in their number. The greatest mass of sclerotia was observed on V8 medium at a temperature of 15°C. Morphological differences between colonies were noted depending on the media used. According to the results of statistical analysis, it was established that temperature had a stronger effect on the growth rate of colonies and the number of formed sclerotia, while the mass of sclerotia depended to a greater extent on the composition of the medium. Conclusion. Thus, S. sclerotiorum is able to develop on a wide range of agar media at different temperatures. The optimal conditions for in vitro cultivation of the white rot pathogen are a temperature of 20°C and potato-dextrose agar medium, which provides both intensive mycelial growth and the formation of a larger number of sclerotia. The results obtained can be used in the development of regulations for cultivation of Sclerotinia sclerotiorum infectious material.