Enhancing of nitrogen fixation by legumes

Aslanbek Kh. Kozyrev,D. Solovyev,G. Burygin,Irina A. Shabanova,Sarra A. Bekuzarova,Larisa I. Weissfeld,Geracim V. Lushenko

doi:10.1051/bioconf/20202302006

Abstract

To increase the legumes’ nitrogen fixation, the seeds were treated with a mixture of biopreparations of 4-aminobenzoic acid (PABA) at a concentration of 0.05% aqueous solution, to with adding of “Nikfan” biopreparation in an amount of 0.1% of the solution volume. The seeds of leguminous grasses such as clover and alfalfa were soaked in this mixture, and 10-15 days after emergence of seedlings, foliar feeding of this concentration was carried out. In the phase of budding and the beginning of flowering, plant productivity was accounted and active nodules were counted. We used variants with seed treatment by industrial strains for each culture, as well as without biopreparation treatment, as a control experiment. As a result of the obtained data, it was found that the use of a biopreparations mixture significantly increases the number of nodules, more biological nitrogen is accumulated in the soil, and protein content in the herbage increases. Correlation was established between the number of nodule bacteria and leaf area at the 4th-5th internodes in clover and the 6th-7th in alfalfa.

Highlights

Clover and alfalfa are the traditional legumes in the North Caucasus, biological nitrogen is accumulated in the soil, which is necessary for the subsequent crop rotation
It is known that the rhizobium-legume symbiosis is a consequence of the evolutionary activity of leguminous plants and nodule bacteria, the result of conjugate natural selection in the process of its historical development
Biological product “Nikfan” is an extract of phytohormones that are obtained from microorganisms of certain strains. This biofertilizer is intended for seed treatment and plant vegetation

Summary

Introduction

Clover and alfalfa are the traditional legumes in the North Caucasus, biological nitrogen is accumulated in the soil, which is necessary for the subsequent crop rotation. To increase their nitrogen-fixing ability, the industrial strain – Rhizobium is used in most cases. With this treatment (seed inoculation), a competition between natural, often ineffective races and artificially created strains occurs, in favor of the latter [1,2,3,4]. It becomes necessary to create varieties with high nitrogen-fixing ability, that is, formation of nodules of bacteria that are capable of fixing nitrogen from the air with formation of the rhizobium-legume symbiosis. The high degree of heritability of symbiotic characters and the direct relationship between nitrogen-fixing ability and plant productivity testify in favor of the effectiveness of symbiotic selection [5,6,7].

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