Using of fungi Macrophomina phaseolina (Tassi) Goid features in soybean breeding for tolerance to charcoal rot (report II)

The report shows that microslerotia of charcoal rot Macrophomina phaseolina (Tassi) Goid. may be formed not only from a plexus of hyphae, but also from separate hyphae, which increases the risk of fungal wilting of soybean plants. The harmfulness of charcoal rot is developing in conditions of water stress against the background of a higher concentration of the cell juice in the tissues of a host plant. In which case microslerotia begin mass formation in the plant tissues, completely closing the openings of vessels of soybean conducting system. Fungal growth stops when the isotonic level of osmotic pressure of nutrient medium is about 930 kPa. A further increase in the osmotic pressure of the nutrient medium causes mass formation of microsclerotia. There was developed the method of selection of breeding material tolerant to the disease for breeding soybean on the basis of plant sampling with the osmotic pressure of the cell juice of not more than 930 kPa in a phase of pod formation and seed ripening.