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The aim of the study was to examine the effects of management practice on microbial properties of soil under soybean production. The study included 180 samples of soil under certified organic soybean production and 80 samples in conventional production system. An abundance of the examined microbial groups was assessed using the indirect dilution method, followed by plating of soil suspension on different selective media, while dehydrogenase and β-glucosidase activity was measured spectrophotometrically. Our data indicated that the management practice affected the structure and activity of microbial com­munities. A significant positive effect of organic farming on Azotobacter spp., free N-fixers and abundance of actinomycetes was identified. The influence of management system for the total number of bacteria, ammonifiers and fungi was not observed. Significantly higher dehydrogenase and β-glucosidase activity was recorded in the soils under organic farming compared to the conventional farming. The obtained results showed an increase in organic matter content, associated with organic soil management, and its positive correlation with soil microbial properties. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 30122]

The objective of this study was to investigate the possibility of using microbial strains as residue decomposers and to determine the effect of these strains on chemical and microbial properties in the residue-amended soil. Greenhouse experiment consisted of eight Bacillus treatments, three Trichoderma treatments, and their combination, all applied to non-sterile chernozem soil amended with wheat straw. Incorporation of wheat straw improved soil chemical and microbial properties, while the extent of residue decom­position under microbial strains was intensified. Microbial treatments significantly affected the soil pH, the content of carbonate, total carbon, soil organic carbon, humus, and available phosphorus and potassium. Bacterial and fungal treatments also significantly influenced the total microbial number, ammonifiers, N2-fixers, fungi, actinomycetes, oligotrophs, copiotrophs, and cellulolytic microorganisms. The effect of microbial treatments varied depending on the applied strains and examined properties, with Bacillus strains being more promising residue decomposers compared to Trichoderma strains. The most effective microbial strains could be used as potential decomposers of crop residues. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR31072]

The objective of this study was to assess the effect of biochar soil amendment (BSA) on chemical and microbial properties in different agricultural soils in Vojvodina Prov­ince. Short-term pot experiment consisted of five biochar application doses (0, 0.5, 1, 2, and 3%) and five contrasting soil types (Mollic Gleysol, Eutric Cambisol, Calcaric Fluvisol, Gleyic Chernozem, and Haplic Chernozem), planted with sunflower (Helianthus annuus L.) and winter wheat (Triticum aestivum L.). The examined chemical and microbial properties were significantly influenced by soil type and interaction of experimental factors. Significant influence of biochar on the contents of calcium carbonate (CaCO3), total nitrogen (N), total carbon (C), soil organic carbon (SOC), humus and potassium (K) of the tested soils was observed. Biochar also significantly affected the number of azotobacters (AZB), fungi (FNG), actino­mycetes (ACT) and copiotrophic bacteria (CB). The effect of BSA varied depending on the applied dose, with higher values of the examined chemical and microbial parameters at higher doses of application. Further studies on using biochar in soils with low fertility will be neces­sary to establish its efficiency as an enhancer for agricultural production in Serbia. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR31072]

During the last decades, intensive application of synthetic fungicides in the agricultural crop protection practice caused growing concern for the existence of toxic chemical residues in food as well as in the whole environment. Instead of using synthetic fungicides, it is suggested that crop protection be carried out by using preparations based on compounds of natural origin (secondary metabolites of plants or microorganisms, including macrofungi from Basidiomycota) as biological control agents. The potential of macrofungal species as biocontrol agents was analyzed in this investigation of eight autochthonous species from different locations in Serbia. Both the terricolous species: Coprinus comatus, Coprinellus truncorum, Amanita strobiliformis, Hydnum repandum and the lignicolous species: Flammulina velutipes, Stereum subtomentosum, Trametes versicolor and Bjerkandera adusta were examined, with an aim to detect some novel sources of antifungal agents. This study surveyed antifungal activity of selected macrofungal extracts (MeOH, EtOH and CHCl3) against phytopathogenic Fusarium and Alternaria strains isolated from garlic, soybean and rice: F. proliferatum, F. verticillioides, F. proliferatum, F. graminearum and A. padwickii. Microdilution method in 96 well microplates was applied for the estimation of antifungal effects of macrofungi extracts in the range from 24.75 to 198.00 mg/ml and determination of minimal inhibitory (MIC) and minimal fungicidal concentration (MFC). EtOH extract of mychorhizal species H. repandum showed antifungal activity against all analyzed phytopathogenic strains, with the strongest effect on Fusarium strains (MIC 24.75 mg/ml; MFC 24.75 mg/ml). Among others, MeOH extracts of S. subtomentosum and C. micaceus showed similar effects while only B. adusta showed slight effect on Fusarium strains (MIC 24.75-99.00 mg/ml; MFC 24.75-99.00 mg/ml) and none effect on A. padwickii. The obtained results indicate the possibility of using examined extracts as efficient antifungal agents and provide the basis for the new formulations of biocontrol agents against phytopathogenic fungi in the future.

The aim of this study was to isolate and identify Bradyrhizobium japonicum strains on the basis of molecular characteristics. From root nodules of different soybean cultivars were obtained 56 isolates, characterized according to morphological, cultural, and biochemical properties. Among these isolates, 33 isolates showing resemblance with Bradyrhizobium sp. were further subjected to molecular identification. Following DNA extraction, a partial 16S rDNA gene sequence from the isolates was amplified by PCR using universal primers fD1 (27F) and rP3 (1492R). Purification and sequencing of the amplified fragments were done in the bio­technology company Macrogen, Seoul, South Korea. Sequences were analyzed using the pro­gram FinchTV and BLAST (Basic Local Alignment Search Tool) and compared to sequences in GenBank and the Bradyrhizobium ID-database for identification. Comparison of the se­quences with the Bradyrhizobium ID-database showed that all tested isolates were identified as Bradyrhizobium japonicum. Each isolate was deposited in the NCBI GenBank database under a unique accession number. Identification of Bradyrhizobium species from root nodules of soybean is of great importance because the symbiosis between rhizobia and legumes are a cheaper and usually more effective agronomic practice for ensuring an adequate supply of nitrogen for legumes, while preserving and improving fertility and productivity of soils. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 31022]

Biocontrol using plant growth-promoting rhizobacteria (PGPR) represents an alternative approach to disease management, since PGPR are known to promote growth and reduce diseases in various crops. Among the different PGPR, members of the genus Bacillus are prefered for most biotechnological uses due to their capability to form extremely resistant spores and produce a wide variety of metabolites with antimicrobial activity. The objective of this research was to identify antagonistic bacteria for management of the plant diseases. Eleven isolates of Bacillus spp. were obtained from the soil samples collected from different localities in the Province of Vojvodina. The antifungal activity of bacterial isolates against five fungal species was examined using a dual plate assay. Bacillus isolates exhibited the highest antifungal activity against Fusarium proliferatum, Fusarium oxysporum f. sp. cepae and Alternaria padwickii, while they had the least antagonistic effect on Fusarium verticillioides and Fusarium graminearum. Molecular identification showed that effective bacterial isolates were identified as Bacillus safensis (B2), Bacillus pumilus (B3, B11), Bacillus subtilis (B5, B7) and Bacillus megaterium (B8, B9). The highest antagonistic activity was exhibited by isolates B5 (from 39% to 62% reduction in fungal growth) and B7 (from 40% to 71% reduction in fungal growth). These isolates of B. subtilis could be used as potential biocontrol agents of plant diseases. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR-31073]

Garlic (Allium sativum L.) is considered to be one of the oldest crops in the world. During 2016, infected garlic bulbs occurred in storages on several localities of the Province of Vojvodina. Symptomatic cloves showed typical rot symptoms such as softened and spongy areas covered with white fungal growth with deep lesions formed on the cloves which became dry over time. A total of 36 isolates of Fusarium species were obtained from diseased cloves of garlic. Colony morphology and microscopic properties of isolated Fusarium species were recorded from the cultures grown on PDA and CLA, respectively. Identification of two chosen isolates was performed by sequencing the EF-1α gene. The TEF sequence of isolate JBL12 showed 100% similarity with several F. tricinctum sequences and sequence of JBL539 showed 99% identity with several F. acuminatum sequences and they were deposited in the NCBI GenBank. Based on the results of the morphological and molecular identification, isolates JBL12 and JBL539 were identified as F. tricinctum and F. acuminatum, respectively, as new causal agents of garlic bulbs rot in Serbia. Specific primers were designed for the PCR identification of the F. tricinctum. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR31030]

The objective of this study was to compare the effects of conventional and organic production system on microbial activity in the soil cultivated with bean and maize crops. The trial in Đurđevo was set up according to the conventional farming system, while organic farming system was used in Futog. Two maize hybrids and two bean cultivars were used in the trial. Soil samples were collected in two periods during 2014 (before sowing, at flowering stage of bean crops, and at 9-11 leaf stage of maize) at two depths, at both locations. The following microbiological parameters were tested: the total number of micro­organisms, number of ammonifiers, Azotobacter sp., free nitrogen fixing bacteria, fungi, actinomycetes, and activity of dehydrogenase enzyme. The results showed that the total number of microorganisms, number of free N-fixers and dehydrogenase activity were higher within organic production, while Azotobacter sp. was more abundant in conventional production. Variations in the number of ammonifiers, fungi and actinomycetes in relation to the type of production were not obtained. Significant differences in microbial activity were also obtained between period and depths of sampling.

The effect on sugar beet yield parameters and microbiological soil status was studied using two techniques of sugar beet inoculation with strains of Azotobacter chroococcum. Cultivar “Drena” was used in the study, and field trial was set under the conditions of organic farming system in Bački Petrovac. A mixture of three strains of Azotobacter chroococcum was used as microbial fertilizer. Inoculation was performed by: (A) incorporation of strains into soil before sowing; and (B) repeated incorporation of strains into soil two weeks after sowing. PGP characterization of the strains confirmed the ability of producing indole-3-acetic acid (IAA) from 12.63 μg ml-1 to 14.95 μg ml-1, nitrogen fixation, and P-solubilization. Positive effects on the number of azotobacter and free nitrogen fixers in rhizosphere were obtained by inoculation, as well as positive effects on the tested sugar beet yield parameters. The largest increase in root yield, yield of crystal sugar, and yield of polarised sugar compared with the control was obtained by repeated soil inoculation, ranging from 22 to 23%.

Аmong 50 bacterial isolates obtained from maize rhizospherе, 13 isolates belonged to the genus Azotobacter. Isolates were biochemically characterized and estimated for pH and halo tolerance ability and antibiotic resistance. According to characterization, the six representative isolates were selected and further screened in vitro for plant growth promoting properties: production of indole-3-acetic acid (IAA), siderophores, hydrogen cyanide (HCN), exopolysaccharides, phosphate solubilization and antifungal activity (vs. Helminthosporium sp., Macrophomina sp., Fusarium sp.). Beside HCN production, PGP properties were detected for all isolates except Azt7. All isolates produced IAA in the medium without L-tryptophan and the amount of produced IAA increased with concentration of precursor in medium. The highest amount of IAA was produced by isolates Azt4 (37.69 and 45.86 μg ml-1) and Azt5 (29.44 and 50.38 μg ml-1) in the medium with addition of L-tryptophan (2.5 and 5 mM). The isolates showed the highest antifungal activity against Helminthosporium sp. and the smallest antagonistic effect on Macrophomina sp. Radial Growth Inhibition (RGI) obtained by the confrontation of isolates with tested phytopathogenic fungi, ranged from 10 to 48%. [Projekat Ministarstva nauke Republike Srbije, br. TR 31073]