ADAPTIVE VALUE OF SOYBEAN VARIETIES GROWN IN DIFFERENT ECOGRADIENTS

The further expansion of soybean acreage and increase in productivity will be facilitated by the introduction of new modern varieties, which are determined by higher productivity potential and a higher level of resistance to the main fungal and bacterial diseases. However, soybean plants are affected by more than 50 diseases. It is known that pathogenic organisms lead to significant losses of the soybean crop (by 15-20%, and by epiphytotic development – by 50%).The results of studies on the assessment of soybean varieties for adaptability (ecological plasticity and stability) in different soil and climatic conditions for resistance to diseases (ascochitosis, yellow mosaic) are presented. Soybean varieties were ranked according to ecological plasticity and stability according to their response to environmental conditions. Our studies have shown that the intensity of the development of ascochitosis and yellow mosaic depends not only on the genetic characteristics of the genotypes, but also on factors related to the growing area, especially the hydrothermal and edaphic conditions of the region. The varieties Oriana – 93.4% and Hoverla – 93.2% stood out for their resistance to ascochitosis damage under different hydrothermal and edaphic conditions, which were characterized by a low reaction to a change in the hydrothermal growing regime, the coefficient of ecological plasticity (bi) < 1. That is, these varieties soybeans provided high indicators of resistance to ascochitosis despite a deficit or sufficient moisture supply in different ecogradient studies. The following varieties stood out for resistance to yellow mosaic: Hoverla – 85.0%, Oriana – 84.9%, Amethyst – 83.0. It should be noted that according to the parameters of ecological plasticity and stability (adaptability), the listed varieties belong to genotypes with a conservative reaction to changes in the agro-environment of cultivation, the coefficient of ecological plasticity (bi) < 1.