Photosynthetic productivity of soybean (Glycine max L.) crops under various fertilization options and pre-sowing seed treatment

The objective of the research is to determine the impact of basic fertilization options, foliar feeding with organo-mineral fertilizer during critical periods of soy plant development, pre-sowing seed treatment with mycorrhizal biofertilizer, and mycorrhizal inoculant in combination with a fungicide on the dynamics of dry matter accumulation by the plants and the net productivity of photosynthesis in the soy crop. Methods. Field (for studying the interaction of the research object with biotic and abiotic factors); morphophysiological (for biological monitoring of productivity elements development during organogenesis stages); statistical (statistical analysis of research results). Results. The article presents research findings on the accumulation of dry matter by soy plants and the net productivity of photosynthesis in the crop across different growth and development stages. Equations have been calculated to establish the relationship between soy seed yield and the indicators of dry mass accumulation by the plants during the pod-filling phase. Conclusions. In modern agricultural practices aimed at achieving maximum seed yield, cultivation technology should include agronomic measures directed towards meeting the biological needs of the plant throughout the vegetation period and reducing the influence of adverse external factors. The highest levels of dry matter accumulation by plants in the study — 26.8–29.2 g/plant, were noted during the pod filling phase in variants with the application of N15P45K60+N30 fertilization, sowing seeds treated with mycorrhizal biopreparation and fungicide, and foliar feeding with organo-mineral fertilizers during the budding and flowering phases. The maximum indicators of net photosynthetic productivity of the crop in the study (8.52–11.29 g/m2×day compared to 5.46 g/m2×day in the absolute control) were observed during the interphase period of flowering and pod filling in variants with N45P45K60 fertilization. For the optimal seed yield of soybean variety Muza observed in the study, the optimal conditions were provided by a cultivation technology involving the application of N15P45K60+N30 fertilizers, pre-sowing seed treatment with mycorrhizal inoculant in combination with fungicide, as well as foliar feeding with organo-mineral fertilizers during the branching or budding phases, when the plants are forming flowers, pods, and seeds within the pods. Through the combination of these agronomic measures, plants accumulate dry matter during the pod filling phase at 25.9–27.4 g/plant, ensuring the net photosynthetic productivity of the crop during this developmental period at 5.60–6.10 g/m2×day, compared to 20.8 g/plant and 5.46 g/m2×day observed in the absolute control, respectively.