One effective way to increase the yield of agricultural crops is pre-sowing seed treatment with nitrogen-fixing and phosphate-mobilising bacteria. The specific features of productivity formation in buckwheat restrict the planned yield and the realisation of varietal potential, leading to an increase in vegetative growth indicators at the early stages of growth and development. The research was conducted on three buckwheat cultivars during 2022-2023 under the conditions of the forest-steppe zone of Ukraine. This study aimed to determine the effect of seed treatment on the content of photosynthetic pigments, biomass accumulation, and leaf area index in buckwheat during the generative period of development. It was found that the influence on biomass growth from mid- flowering to fruit formation was limited, though different trends in the formation of photosynthetic pigments in leaves were observed. The biopreparations significantly increased the content of photosynthetic pigments at the budding stage (BBCH 51), mainly due to chlorophyll a, while at the flowering stage (BBCH 65), phosphate-mobilising complexes were most effective. It was established that seed treatment with nitrogen-fixing bacteria enabled buckwheat to form a leaf area index of 5.27-5.48 at the fruit formation stage, which was significantly higher compared with the control (4.19). At the same time, biomass accumulation during the generative period changed insignificantly across the seed treatment options, but morphological changes were noted that contributed to higher yields and, consequently, greater productivity. It was established that pre-sowing seed treatment has a significant effect on biometric indicators and yield, though the varietal factor often manifests itself, indicating the prospects for further research into evaluating the formation of the buckwheat generative apparatus under the influence of microbiological preparations
chlorophyll content; dry matter; leaf area index; net photosynthetic productivity; yield