PHOTOSYNTHETIC PRODUCTIVITY OF SOY CROPS DEPENDS ON PRE-SOWING TREATMENT AND FERTILIZER

The scientific publication presents the results of experimental research on the influence of pre-sowing seed treatment and fertilization system on the photosynthetic productivity of Bettina and Vyshivanka soybean crops.Photosynthetic activity is the main factor behind biomass accumulation and yield formation in crops. Leaf area index (LAI) and photosynthetic potential (PP) are key indicators of how a soybean crop responds to environmental conditions and agronomic practices. Optimising the formation of the assimilating surface through seed inoculation and balanced macro- and micronutrient supply therefore remains an important task. The purpose of the study was to determine the effect of inoculation and fertilisation on LAI and PP of soybean varieties Bettina and Vyshyvanka. A three-factor field experiment was carried out in 2024–2025 at the agricultural limited liability company "Druzhba" (Vinnytsia district). Factor A was variety (Bettina, Vyshyvanka); factor B was inoculation (no inoculation; HighCot Super); factor C was fertilisation (control without fertilisers; N20P20S9 with Maxim XL seed treatment as the background; background + Wonder Mikro; background + Wonder Mikro + Wonder Yelow; background + Wonder Mikro + Wonder Yelow + Wonder Bor). The accounting area of a plot was 25 m², with four replications. LAI was determined at BBCH 51-59, 60-69 and 80-85, and PP over the period BBCH 09–87. Results. LAI and PP depended on variety, seed pre-treatment and nutrient supply. The lowest values were recorded in the uninoculated, unfertilised control, and the highest where inoculation, background fertilisation and the full foliar programme were combined. In Bettina, LAI on this variant was 2.56, 4.72 and 4.47 m²/m² at BBCH 51-59, 60-69 and 80-85, exceeding the control by 0.35, 0.41 and 0.42 m²/m², while PP reached 3.044 million m²•days/ha (1.295 above the control). Inoculation increased PP by 13.1% in Bettina and 16.0% in Vyshyvanka. Combining seed inoculation, mineral fertilisation and foliar feeding with micronutrients ensures the largest leaf area and photosynthetic potential of soybean crops. Bettina responded more strongly than Vyshyvanka under identical agronomic practices.