The efficiency of the introduction of nodule bacteria, microsymbionts of legumes in agrocenoses, largely depends on the activity of biologically active substances’ biosynthesis by diazotrophs. Seed bacterization with effective rhizobia strains capable of synthesizing exometabolites for phytostimulating activity not only promotes the formation and functioning of symbiosis but also creates the conditions for increasing plant resistance to adverse environmental conditions. The aim of the work was to research the symbiotic activity, efficiency and ability of chickpea rhizobia new strains to biosynthesize phytohormonal exometabolites of cytokinin nature. Methods. Microbiological, physiological, cytological, biochemical, and physicochemical. Results. New strains of Mesorhizobium ciceri ND-101 and Mesorhizobium ciceri ND-64 were shown to have different symbiotic activity. The efficiency of inoculation of Skarb chickpea seeds with bacterial suspension of Mesorhizobiu mciceri ND-101 was at the same level with the industrial strain of Mesorhizobium ciceri H-12. Bacterization of Mesorhizobium ciceri ND-64 increased the chickpea roots nodules by 69%, their weight by 74%, and nitrogenase activity by 73% relative to the positive control (inoculation with Mesorhizobium ciceri H-12), as well as increased chickpeas yield by 22%. It was established that Mesorhizobium ciceri ND-64 strain exhibits the highest cytokinin activity in the bioassay. Cytokinins in the total amount of 174.94 μg/g of completely dry biomass were detected in the culture medium of Mesorhizobium ciceri ND-64, which is 53% higher than that of Mesorhizobium ciceri ND-101 strain and 99% higher than that of Mesorhizobium ciceri H-12 strain. Conclusions. Mesorhizobium ciceri ND-64 strain with high nitrogen-fixing activity and symbiotic efficiency is capable to synthesize a relatively high amount of extracellular cytokinins. The high concentration of cytokinins indicates their important role in the formation and functioning of nodules, as they stimulate the proliferation of root tissues and, in this way, have a positive effect on the chickpea productivity.

The paper examined the impact of different lighting sources on the growth and development of the Antonina and Solnechnyi potato varieties, grown in vitro. The object of the experiment was pathogen free parent micro clones of potatoes, derived from apical meristem by cultivation in the standard Murashige and Skoog medium with modifications. The following sources of light were used: OSRAM luminescent lamps, with the predominant red and blue, power 36 W; OSRAM luminescent lamps, cold daylight, power 36 W; TELEFUNKEN linear light-emitting-diode (LED)lamps - 4200 K, white light, power 18W; linear LED lamps TELEFUNKEN - 2700 K, warm white light, power 18 W; LED lamps red-blue, diodes ratio 3:1, power 32 W and LED lamps full-spectrum, power 32 W. The effect of these lighting sources on the length of plants, time of root emergence, number of leaves / internodes, mass of the plants and leaves, shoots and roots, and the surface area of the leaf plate was studied. The operating costs for the studied lighting sources was calculated. It was discovered that for the cultivation of the test tube plants varieties Antonina and Solnechnyi with the aim to obtain the maximum number of new test plants, LED lamps 2700 K are the most suitable ones. For the cultivation of test plants of the chosen varieties to prepare them for further transplantation on aero-hydroponic system for producing mini tubers, full-spectrum LED lamps are recommended.

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The іnoculation and plant growth regulators have been studied for their effect on the symbiotic nitrogen fixation and productivity of soybean in the field experiments. It was shown that nitraginisation with the high efficient strain B. japonicum 71т (UCМ В-6035) promotes active rhizobium-soybean nodulation system, and crude protein yield increasing as the result of the symbiosis efficiency. The combined use of Nitragin and plant growth regulators requires attention to both cultivar peculiarities of macrosymbionts and specific action of these preparations.