: 78-82
National University Lviv Polytechnic
National University Lviv Polytechnic
Lviv Polytechnic National University
National University Lviv Polytechnic

Organic agriculture (OA) is actively developing in Ukraine. The idea of OA is to refuse to use GMO, antibiotics, pesticides and mineral fertilizers, but instead – to use biopreparations for stimulating plant growth, yield increase, preventing and treating plants from diseases, which are caused by mushrooms and bacteria.

This work is devoted to the study of bacteria of the genus Rhizobium, which are capable of nitrogen fixation, phosphate mobilization, phytohormones synthesis, biocontrol, and also they can be used as bioinoculants for leguminous plants. This microorganism is used for the receiving of monobacterial biopreparations, but the literature analysis showed that preparations which are containing compositions of several different representatives of rhizospheric microorganisms are better. Bacteria of the genus Azotobacter are promising for the use in composition of polybacterial biopreparations. This group of microorganisms has the ability to fix atmospheric nitrogen, phytohormones synthesis and decompose chemicals that pollute the environment.

The aim of the work is to isolate and study bacteria of the genus Rhizobium and Azotobacter to create a bacterial composition and test its growth-stimulating properties.

Bacteria of the genus Azotobacter was isolated from the rhizosphere of the lettuce (Lactuca sativa). The accounting of bacteria in samples of rhizosphere soil was carried out using the Krasilnik method. To isolate the culture of bacteria, the selective Ashby environment was used (pH = 7-7.2, exposure - 7 days, t = 28 ± 2 ○C). Formed colonies were separated based on morphological features. The presence of capsules, significant mucus formation and pigmentation made it possible to characterize the selected microorganism as a representative of the genus Azotobacter.

Bacteria of the genus Rhizobium (R. leguminosarum) were extracted on leguminous agar from nodule formations of roots of pea sowing (Risum sativum). They were incubated at 28 ± 2 ○C for 1-2 days. Pure, whitish, opaque colonies, similar to drops of stearin, were formed. There were gram-negative bacteria of the rod-shaped form.

The growth-stimulating ability of monobacterial suspensions of Azotobacter and Rhizobium, as well as their complex in the ratio of 1: 1, was checked. Working suspensions with the concentration of microorganisms of 1∙109 CFU/ml were prepared. The industrial bioproduct Azotofit-R was used as a comparison culture. Suspensions were used for germination of lettuce seeds. The weight of the Lactuca sativa sprouts in non-sterile conditions, grown from the seeds inoculated with this complex, is 39.9% and 49.6% higher than noninoculated and inoculated with the Azotophyte-R biopreparation seeds, respectively. Biological agent R. leguminosarum, used in the form of a monobacterial suspension, are also capable of successfully colonizing the rhizosphere and stimulating the growth of nonlegumes. The weight of Lactuca sativa sprouts in non-sterile conditions grown from the seeds, inoculated with this bacteria, is 26.44% higher than that of noninoculated, and 38.3% higher than that of the seeds treated with the Azotophyte-R biopreparation.

Thus, the use of a polibacterial composition based on the genera of Rhizobium and Azotobacter bacteria for stimulation of non-leguminous plants growth is promising.

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