Abstract The study investigated the effects of multifunctional plant growth regulators (PGRs) on yield formation in sunflower hybrids under contrasting hydrothermal conditions of the steppe zone of Ukraine using integrated field experiments and satellite-based monitoring. It was established that crop productivity is determined by the interaction among hybrid genotype characteristics, moisture regime, and the intensity of canopy photosynthetic activity. Application of plant growth regulators ensured a consistent increase in seed yield, with the biological product Helafit Combi demonstrating higher agronomic efficiency compared to the chemical regulator Architect™. The spatiotemporal dynamics of agrocenosis condition were assessed using the Normalized Difference Vegetation Index (NDVI) derived from Sentinel-2 satellite imagery during critical stages of organogenesis. A strong correlation was identified between phase-specific NDVI values and final yield, with the highest correlation observed during the flowering stage. Universal, genotype-specific, and year-type-differentiated predictive models were developed, all of which demonstrated high explanatory power and strong forecasting accuracy. The findings substantiate the feasibility of integrating remote sensing data with field-based measurements for operational yield assessment and adaptive crop management of sunflower under conditions of increasing climatic variability.
Пічура et al. (Sun,) studied this question.