DYNAMIC PARAMETERS OF PRODUCTIONAL PROCESS OF EARLY RIPENING SOYBEAN VARIETIES DEPENDING ON MOISTURE CONDITIONS OF THE VEGETATION PERIOD

Due to change of temperature and moisture regime and the shift of the isotherm of the sum of active temperatures from north to south in the Central region of Non-Black Soil zone, it became possible to expand the areas occupied by soybean crops and introduce new crops to more northern regions. In this regard, it became necessary to analyze the change of dynamic parameters of development of early-ripening soybean varieties of different origin - the northern ecotype, southern and Far Eastern ones in the conditions of the Central region of the Non-lack Soil zone with sufficient moisture supply as well as arid conditions during the growing season. The studied soybean varieties had differences in the growing season duration and the sum of active temperatures. The growing season of varieties of the northern ecotype was 85–100 days, the sum of active temperatures was 1700–1900°C; as for the southern ones: 90–105 days and 1900–2200°C; and the Far Eastern varieties: 95–105 days and 2000–2300°C. The maximum dry biomass averaged 5400–5700 kg/ha under conditions of favorable hydrothermal regime of the growing season, and did not exceed 3400 kg/ha under dry conditions. It was found that in case of sufficient moisture supply (HTC = 1–1.5), the southern varieties are more consistent with the possible variability of thermal resources in the Central region of the Non-Black Soil zone in terms of development than the Far Eastern ones and, along with the varieties of the northern ecotype, can be recommended for cultivation in the region. As far as arid conditions (HTC < 1) is concerned, no fundamental differences between the groups of varieties in terms of production process characteristics were revealed. The duration of the growing season correlated with the temperature and moisture regime of the growing season. The growing season was reduced by 5–8 days on average for varieties in dry years (HTC < 1), in wet years (HTC > 1.6) it increased by 6–10 days.