PECULIARITIES OF FORMATION AND FUNCTIONING OF THE SOYBEAN–BRADYRHIZOBIUM JAPONICUM SYMBIOTIC APPARATUS IN RELATION TO PHOTOSYNTHETIC ACTIVITY UNDER THE INFLUENCE OF SEED PROTECTANTS

Abstract

The aim of work was to investigate the influence of seed treatment with two preparations of fungicidal action, differing in the active substances composition, on the formation and functioning of legume-rhizobial symbiosis in interaction with the photosynthetic apparatus of soybean plants. It was established that in plants treated with preparation Fever, the nitrogen-fixing activity (NFA) difference with the control was insignificant, but under the impact of the preparation Standak Top NFA was by 63% less at the stage of three true leaves, by 48% – at the stage of budding, and by 34% – at the stage of budding–flowering. The net photosynthetic rate, calculated per leaf area unit, was lower than control at all investigated stages of soybean plants development in the variants with the seed protectants applying. A fairly close positive correlations (R²Â = 0.79) were observed between the average weight of one nodule and its NFA, and between the last and total NFA of the whole plant (R² = 0.78). Close correlations between plant NFA, chlorophyll content in leaves, and net photosynthetic rate were revealed. It was concluded that seed protectants significantly influenced on nitrogen fixation and photosynthesis.

The strength of manifestation, and the sign of this influence in comparison with the relevant parameters of the control plants depended on the preparation, the stage of plant development, as well as on the index (nodules formation, nitrogen-fixing activity, photosynthetic, chlorophyll content, chlorophyll index, biological productivity of soybean plants) under consideration.