V.G. Kuryata*, L.A. Golunova, I.V. Poprotska and O.O. Khodanitska

The effect of pre-sowing inoculation of the soybean (Glycine max (L.) Merr.) cultivar ‘Podilska 1’ seeds, with the effectual strain of Bradyrhizobium japonicum 71 t, and the subsequent spraying the plants (within the stage of budding) with the antigibberellic preparation of chlormequat chloride in regard to the soy-rhizobium complex formation, as well as the symbiotic nitrogen fixation activity have been studied within the experiment. The anatomic- morphological and physiological parameters of the source and sink functioning as a system, the peculiarities of the crop formation and its quality affected by inoculation with strain 71 t and the subsequent retardant preparation were tested. As it goes out of the data, the use of the retardant in addition to inoculation proved to be effectual, for its use caused limitation of the linear growth of the plant, stimulating branching of the stem and resulted in growth of leaves in number, including the overall area of laminae per plant. Chlormequat chloride was a proven cause of more powerful mesostructure formation, previously due to the enhanced development of chlorenchyme towards growth of pure photosynthesis productivity. Moreover, the retardant caused the formation of a more powerful source-sink sphere of the plant, which provided with assimilates both the processes of symbiotic assimilation and the processes of formation and development of beans and seeds. The results obtained in the research testify to the strengthening of mutual interdependence of bean- rhizobium complexes: the number and weight of the nodules on the roots of inoculated plants increased due to the preparation. In consequence of the enhanced provision of bacteria with assimilates the nitrogen efficacy of the bean-rhesobium complexes essentially increased. It is also important to mention that the formation of plant productivity depended on enhanced supply of the processes of symbiotic nitrogen fixation with assimilates which led to a shift in the peak of activity of nitrogenase to a later stage of ontogenesis - the phase of green bean. Under conditions of the seed inoculation with strain 71t, the activity of nitrate reduction was higher than that of control, and increased from the phase of flowering to the phase of bean formation both in the roots and in the leaves of soybean plants. The use of chlormequat chloride against the background inoculation with the strain did not influence the activity of the ferments in the roots, though reduced it in the leaves, especially in the phase of bean formation. Hence, the effect of retardant chlormequat chloride on the nitrogen redistribution is directly carried out through stimulation of the forming and functioning of the bean-rhisobium complex, and not through the activation of nitrate reduction. Because of increased branching of the stems and placing of a greater number of beans, the formation of a larger leaf surface and the growth of photosynthetic activity per unit of the blade surface area, improvement of the nitrogen nutrition increased the yield capacity of the crop and improved the quality of the products – the contents of nitrogen in the seeds increased and the contents of unsaturated fatty acids in the soybean oil increased either. The suggested formula of the preparation did not cause the accumulation of chlormequat chloride in soybean seeds above the allowed norms.

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