The study of the dynamics of formation and functioning of symbiosis between nodule bacteria and chickpea plants was carried out in the northern region of Ukraine in the experimental plots, where the local population of chickpea mesorhizobia began to form. A new strain of Mesorhizobium ciceri ND-64 and a reference Mesorhizobium ciceri H-12 were used to inoculate Cicer arietinum seeds. The field study determined the number, weight, nitrogenase activity of nodules on the chickpea roots, dry green mass and mass of roots of chickpea plants of Pam'iat' variety. Samplings were carried out nine times in different phases of plant vegetation, starting from the branching phase and ending with the phase of complete maturity of seeds. The study showed that round and oval nodules appeared on the roots of chickpea plants during the branching stage. Gradually, they increased in size and in the phase of budding formed splices. The largest number of nodules (43.1 units/plant) was formed in the bean formation phase. The highest nitrogenase activity of the nodules was registered in the flowering phase. It was found that the bacterization of M. ciceri ND-64 promotes earlier formation and long-term functioning of the symbiotic apparatus in comparison with the reference strain and the control variant. The highest symbiotic rates under inoculation with M. ciceri ND-64 were registered at the beginning of the bean formation phase. In the control variant and with inoculation of M. ciceri H-12, these parameters were the highest later (at the end of the bean formation phase) and rapidly decreased in the subsequent phases, while the nodules formed by M. ciceri ND-64 continued to functioning actively. The positive effect of inoculation of chickpea seeds with a suspension of M. ciceri ND-64 on the increase in the number of beans and seeds per plant, weight of 1000 seeds and yield of chickpea plants was shown. Considering the obtained data, the new strain M. ciceri ND-64 is a promising bioagent of a microbial preparation for bacterization of chickpea

Objective. Study the competitiveness, complementarity and symbiotic activity of a new strain of chickpea nodule bacteria Mesorhizobium ciceri ND-64, study the influence of seed inoculation on the productivity and yield of chickpea varieties of Ukrainian selection under their cultivation in different soil and climatic zones of Ukraine. Methods. Serological, gas chromatography, field experiment and statistical. Results. The use of a new strain of M. ciceri ND-64 for pre-sowing bacterization of chickpea seeds of varieties Skarb, Admiral, Odysei, Budzhak, Triumf and Pamiat upon growing in field experiments in the Steppe zone against the background of the local population of nodule bacteria contributes to a significant increase in nitrogen-fixing nodules by 5 % to 67 %, an increase in the mass of nodules by 10 % to 67 % and nitrogenase activity 26 % to 150 % compared with the positive control (inoculation with the reference strain of M. ciceri H-12). The use of M. ciceri ND- 64 for pre-sowing bacterization of chickpea seeds under cultivation in the Steppe zone of Ukraine also had a positive effect on increasing the yield of chickpea — by 4 % to 18 % compared to the positive control. Inoculation with a new strain of chickpea seeds of varieties Skarb, Triumf and Pamiat contributed to the formation of higher number of nodules (by 57 % to 89 %), increaseed mass of nodules (2.2–2.9 times) and their nitrogenase activity (2–4 times) compared with the positive control upon cultivation in the Polissia zone on the fields where there is no population of chickpea rhizobia. Under these conditions, an increase in structural parameters of yield, the highest gain in chickpea yield, increase in photosynthetic activity and protein content in grain upon inoculation with M. ciceri ND-64 was shown. Obtaining a specific antisera by immunization of rabbits allowed to detect serological relatedness of M. ciceri ND-64, M. ciceri H-101, Mesorhizobium sp. ND-601 and M. ciceri ND-64, isolated from chickpea nodules of Skarb and Pamiat varieties. The competitiveness of M. ciceri ND-64 was determined using the immunological method in the field experiment. It was found that 100 % of nodules have been formed by the representatives of M. ciceri ND-64 in the variant where this serological group was applied for inoculation in the variant with inoculation of the strain M. ciceri ND-64 100 % of the nodules were formed by representatives of this serogroup. Conclusion. M. ciceri ND-64 strain is an effective microsymbiont of chickpea plants, due to its virulence, competitiveness, nitrogen-fixing properties. According to the results of field experiments, it was shown that the new strain, complementary to all studied varieties differing in seed size and shape, type of bush and average height, forms an effective symbiosis for growing chickpea plants both against the active local population of rhizobia and upon the absence of M. cicerі population in the soil. Symbiotic parameters upon seed treatment with suspension of M. ciceri ND-64 exceed these values in the variants with inoculation using the reference strain of M. ciceri H-12 and strains isolated from the nodules of each study variety. Therefore, M. ciceri ND-64 can be used as a bioagent of a microbial preparation for inoculation of chickpea of different varieties in order to form an effective bean-rhizobial symbiosis, increase the productivity of this culture and improve seed quality.

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.

Objective. Study the effect of chickpea seed inoculation with a suspension of Mesorhizobiumciceri ND-64 on crop yields, calculate the economic and bioenergy efficiency of seed bacterization.Methods. Microbiological, field experiment, economic, statistical. Results. It was shown that presowing inoculation of chickpea seeds with M. ciceri ND-64 during cultivation of this culture inPolissia of Ukraine conditions contributed to the increased efficiency of legume-rhizobial symbiosis. During three years of research there was an increase in structural parameters: the numberof beans per plant — by 15–42 %, seeds from the plant — by 12–32 %, weight of seeds from theplant — by 12–37 %, weight of 1000 seeds — by 6–9 % relative to positive (with inoculation usingreference strain of M. ciceri H-12) and absolute (without inoculation) controls, respectively. Theyield of Pamiat variety chickpeas increased by 12.8–26.5 %. The amount of profit when bacterialsuspension of M. ciceri ND-64 was applied for seed bacterization per 1 ha of sown area was UAH10,795 and the level of profitability was 106.1 %. The payback of each hryvnia of additional costswith additional income was UAH 19.43 after inoculation with M. ciceri H-12 and UAH 30.88 after M. ciceri ND-64. With anthropogenic energy consumption of 10,479 MJ in the variant with bacterization using M. ciceri ND-64 per 1 ha of sown area, the energy content of the obtained grain was26,181 MJ, respectively, the energy efficiency coefficient was 2.50. The additional energy costs associated with the use of M. ciceri ND-64 were 16.56 times paid back by the energy of the additionalcrop. Conclusion. The use of M. ciceri ND-64 for pre-sowing inoculation of chickpea seeds ofPamiat variety provided an increase in the number of seeds from the plant by 42 %, weight of seedsfrom the plant by 32 %, weight of 1000 seeds by 9 % and increase crop yields by 26.5 % relative tocontrol when the crop was cultivated in Polissia area during three years of research. All parameters of economic and energy efficiency of pre-sowing bacterization with M. ciceri ND-64 are moreeffective in comparison with inoculation using M. ciceri H-12.

Objective. To compare morphological, cultural, physiological, biochemical, and symbiotic properties of strains of nodule chickpea bacteria isolated from different soil and climatic zones of Ukraine. Methods. Microbiological, microscopic, gas-chromatographic, statistical. Results. From the nodules of chickpea plant of varieties Skarb, Admiral, Odissei, Budzhak, Triumf and Pamiat, grown in the steppe zone of Ukraine (Region of Odessa), where an active rhizobia population was formed due to the continuous cultivation of this crop, 58 isolates of bacteria were isolated; 11 iso-lates were isolated from the nodules of plants of Triumf and Pamiat varieties selected in the forest-steppe zone (Region of Lviv), in the fields where chickpea was grown for the first time. It has been established that the strains of Mesorhizobium sp. 1 and Mesorhizobium sp. 2, which were isolated from the nodules of chickpea plants grown in the fields with an active rhizobia population of this culture, form colonies of 2–4 mm in size at day 3–4 on the mannitol yeast agar and, according to cultural and morphological properties correspond to the characteristics of the species Mesorhizo-bium ciceri. Their use for pre-sowing chickpea inoculation increases the mass of nodules (2– 3 times) and nitrogenase activity (1.4–2 times) compared with the results obtained using the pro-duction strain of Mesorhizobium ciceri H-12. Inoculation with Mesorhizobium sp. 11, isolated from the forest-steppe zone, which on a mannitol yeast agar forms a colony of 1–2 mm in size at day 5–6, contributed to a significant increase in the number of nodules on the roots of plants (by 40.5 %), their mass (by 31 %), but the increase in nitrogenase activity was negligible. Conclusion. Strains of Mesorhizobium sp. isolated from chickpea nodules grown in different soil-climatic zones of Ukraine, have similar cell morphology, but differ in growth rate, cultural, physiological, biochemi-cal, and symbiotic properties.