Dynamics of formation and functioning of legume-rhizobial symbiosis Mesorhizobium ciceri-Cicer arietinum (variety Pam'iat')

Abstract

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

Symbiotic Efficiency and Cytokinin Activity of New Mesorhizobium cicerі Strains

“…Among domestic and foreign scientists, there is no consensus on the direct relationship between the ability of nodule bacteria to synthesize cytokinin exometabolites and their symbiotic eff ectiveness [6-8, 21, 22]. Studies of domestic scientists indicate that the ability of Our fi ndings prove that the studied strain of M. ciceri ND-64, which is characterized by high indicators of symbiotic effi ciency and contributes to the early formation of symbiosis (compared to the industrial strain of M. ciceri H-12), which actively functions throughout the entire period of plant ontogenesis [24], contains a relatively high amount of exometabolites of cytokinin nature in the culture medium. In particular, the ability of M. ciceri ND-64 bacteria to produce zeatin riboside in the amount of 174.94 μg/g of absolutely dry biomass, which exceeds the amount of this cytokinin in the culture medium of the industrial strain M. ciceri H-12 by 99% and by 53% in M. ciceri ND-101, consistent with its high nitrogenase activity and effi ciency of symbiosis with chickpea plants.…”