Cyanobacteria and algae from biofilm at the entrance zone of Petnica Cave

The importance of biofilms in caves, the diversity of microorganisms in them, their mutual relationship and relationship with the substratum are among the advancing research topics in microbial biospeleology. This research is making contribution to the knowledge about biofilms at cave entrances and phototrophic communities in them. In that manner, biofilms from the entrance zone of the Petnica Cave were examined. Light microscopy showed that cyanobacteria were exclusively dominant phototrophs (34 taxa out of 39 total taxa recorded) with coccoid forms prevailing (28 taxa); simple trichal forms were present to a lesser extent, while heterocytous ones were completely absent. Genera Gloeocapsa, Chroococcus,Gloeothece and Leptolyngbya were the most diverse. Four green algal genera characteristic for aerophytic habitats (Apatococcus, Desmococcus, Haematococcus and Trentepohlia) were also recorded, while Bacillariophytawere observed sporadically. Three groups of sampling sites were distinguished based on recorded taxa, their richness and similarity, using non-metric multidimensional scaling (NMDS). Quantitative biofilm characteristics were also assessed - the content of chlorophyll a (Chl a) was determined, as well as the contents of water, organic and inorganic matter. Chl a had a significant positive correlation with the content of organic matter (r=0.904, P=0.013).

Assessment of irrigation water quality at the territory of Vojvodina Province (Serbia)

Intensive crop cultivation systems require continuous monitoring of irrigation water quality as well as the control of physical and chemical soil properties. In view of the ongoing climate change and a dramatic decrease in soil organic matter content, the use of low quality irrigation water and its adverse effects on soil, cultivated plants and irrigation equipment must not be overlooked. The aim of this paper was to evaluate general quality of irrigation water from the different water intake sources in the Vojvodina Province. The paper presents the results of irrigation water quality, collected during 2018 and 2019. The research included 140 irrigation water samples obtained from three different intake structures which collect water from wells, canals or reservoirs. Water quality was assessed using the following parameters: pH value, electrical conductivity (EC), total dissolved solids (TDS), ionic balance, sodium adsorption ratio (SAR) and residual sodium carbonate (RSC) value. Water quality diagram given by the US Salinity Laboratory (USSL) and FAO guidelines for interpretation water quality for irrigation was used. Additionally, the Nejgebauer classification for irrigation water, developed specifically for the area of Vojvodina, was used as a third classification. Based on the results of mineralization of the irrigation water, the following values of the observed parameters were determined: average pH of the analyzed water samples were 7.89, ranged from 7.14 to 9.01, while electrical conductivity values ranged from 0.10 to 3.50 dS/m, with an average of 0.85 dS/m. TDS analysis resulted in a wide range of values, from 112 mg/l to 2,384 mg/l, with an average of 529,22 mg/l. SAR values varied between 0.04-16.52 with a satisfactory average of 1.97. The USSL water classification produced similar results as FAO classification and RSC index <0, indicating that 57% of investigating samples are without concerns for irrigation use, whereas Nejgebauers classification and RSC index 0-1.25 show that over 75% of analyzed samples are suitable and safe for irrigation and soil properties. Since the quality of irrigation water significantly affects plant productivity, as it determines the chemical and physical properties of agricultural land, monitoring of water quality for irrigation is of high importance.

Postharvest decay of mandarin fruit in Serbia caused by Penicillium expansum

Mandarin fruits are one of the most popular among the Citrus genus. They are consumed because of their nutritional and health benefits, as well as pleasant taste and smell. This paper describes the identification and characterization of Penicillium expansum, isolated from molded mandarin fruits. The obtained isolates were cultivated on five media [Czapek Yeast Autolysate agar (CYA), MEA (Malt extract agar), Creatine sucrose agar (CREA), Yeast extract sucrose agar (YES), and Oatmeal agar (OA)] and at five different incubation temperatures (5, 15, 25, 30, and 37 ?C). Isolates were sequenced for two molecular loci: internal transcribed spacer and beta-tubulin. Based on the results from morphological, physiological, molecular, and phylogenetic analyses, the recovered isolates were identified as P. expansum. The isolated species was confirmed as pathogenic to mandarin fruits in a pathogenicity test. To the best of our knowledge, this is the first report of P. expansum as a postharvest pathogen of mandarin fruit in Serbia.

Occurrence of Botryococcus terribilis Komárek & Marvan in a small sandpit lake: The first report from Serbia

Alkaline saline ponds and lakes are habitats with unique biodiversity. The green alga of the genus Botryococcus was accidentally discovered during a micro-algal survey of these habitats in Serbia. Species B. terribilis was found and identified for the first time in Serbia in the small sandpit lake of the Rusanda Nature Park. The first sampling was incomplete due to the unknown origin of the orange-red surface scum. After the identity of the species had been confirmed, three additional samplings were conducted aiming to collect phytoplankton and water samples for physical and chemical analyses. Major anions and cations were analysed in order to characterize the chemical type of sandpit lake, as well as nutrient content. Sandpit lake is an alkaline water body that belongs to sodium bicarbonate chemical type. Morphometric analysis of B. terribilis was performed using light and transmission electron microscopy. B. terribilis was found to be numerous in the phytoplankton community in late autumn and winter. Species from the genus Botryococcus are known as a rich source of different lipids and this discovery can be the first step in the further biotechnological application of this species in sustainable biofuel production.

Effects of drought stress on germination and seedling growth of different field pea varieties

Germination and seedling growth of seven genotypes of field pea (Pisum sativum L.) were studied in PEG-6000 solution having osmotic potentials -0.1 and -0.2 MPa. A study was undertaken to evaluate the influence of different osmotic potentials (MPa) on seed germination percentage (GP) and mean germination time (MGT). Results show that the percentage of germination decreased with a decrease in osmotic potential, while mean germination time increased. Variety Javor is much more sensitive than the other varieties at all levels of osmotic stress. By contrast, the lowest sensitivity of germination and MGT was found in varieties Mraz and Trezor. Seed germination tests at -0.1 to -0.2 MPa have the potential to be used as tests in field pea. Osmotic stress exposure and its duration significantly affected the growth of seedlings (shoot and root) and the accumulation of biomass, while its effect was more prominent on the growth of the shoot than on root growth, which was also confirmed by the root tolerance index.

Scripting languages for geomorphological modelling and topographic visualization of Serbia

Scripting cartographic technique is a new method of geospatial data visualization - especially with thematic mapping such as geomorphological models. The purpose of this study was to explore the use of Generic Mapping Tools (GMT) and R for geomorphological and topographic mapping of Serbia using free open datasets (DEM, SRTM/ GEBCO, OpenStreetMap). Current trend in education and research of distance-based and online-based education suggests that application of free high-resolution data for modelling and mapping by open source cartographic toolsets are more likely to result in deep geospatial analysis of the geomorphology of Balkans with associated geographic phenomena: hydrology, soils, vegetation, geology. Presented fragments of scripts aim to demonstrate the technical usage of R and GMT coding in cartographic workflow with a case study on Serbia. Using qualitative descriptive cartographic approach to visualize the slope, aspect and terrain elevations over the country and the ?raster? package provided by R, it was found that the geomorphology of Serbia spatially differs in southern and northern parts of the country resulting in regional geologic evolution and tectonic dynamics of the Balkan formation. The presented maps portrayed general distribution of the landforms in Serbian region of Balkans. The research contributes to the methodological development and testing of the cartographic techniques as well as geomorphological and environmental studies of Serbia.

Biodiversity indices for the Futog park (Novi Sad, Serbia)

Biodiversity and biodiversity preservation are some of the most important topics in ecology. Protecting biodiversity in urban ecosystems is especially challenging. Urban parks are a valuable part of green infrastructure in cities, as they contribute to preserving natural habitats for many species. Biodiversity can be quantified by calculating different diversity indices, and in this paper, we have calculated alpha indices (Shannon, Simpson, Fisher, Berger-Parker and Margalef index) and beta indices (Sorensen index, Jaccard distance and Bray-Curtis index) for the Futog park in Novi Sad, Serbia, within two periods, 2005 and 2020. The goal of the paper is to analyze the current values of biodiversity indices in the park and compare them with the ones from 15 years ago. In addition to the analysis of biodiversity indices values, the paper provides the comparison of taxonomic structure of flora, and the abundance of native, endemic and invasive species in the park, in 2005 and 2020. The results show that the values of biodiversity indices have decreased in the indicated period of time, and one of the main causes can be related to the spread of invasive species within the park. For calculation purposes, we have used the R program and the R package ?vegan?.

The use of degraded peatlands for biomass production

The goal of this research is an assessment of the possible use of peatlands biomass and straw for the production of mixed bio-pellets. Peaty soils are a specific type of soils formed as the result of wetlands drainage. Peat mining is completed by the factory if the layer of the peat is less than 1-2 meters and not enough deep for effective mechanical excavation. After the peat excavation is finished, the biggest problem is the use of these lands for other purposes. One of the perspective directions is rewetting of post-mining peatlands to stimulate the growth of common reed, cattail, fescue, sedge, and other grasses which may grow in natural conditions, and also improve conditions for the cultivation of other plants, including trees. The yield of wetland grass in Belarus varies from 8.1 to 14 DM g ha-1 per year. The yield of willow wood can reach 8-10 of DM g ha-1 per year. The highest prime cost of biomass is obtained for willow wood, but it will be lower with the enlargement of the plantation area. Pellets with a high content of wood residues (sawdust) have the best technological parameters including calorific value when compared to pellets from only peat and peat plus straw. Biomass production on degraded peaty soils has also an ecological effect. The cost of carbon quotas on the market varies from 20 to 25 euro per ton, and biomass production can provide additional profit in the case of CO2 emissions trading depending on the biomass content in the fuel.

Morphological and molecular characterization of Fusarium graminearum Schwabe as a causal agent of Hyssopus officinalis L. seed rot

Symptoms of seed rot of Hyssopus officinalis L. were noticed during seed health testing in 2018. According to morphological and cultural characteristics, isolates belong to Fusarium spp. and Alternaria spp.. Based on morphological and pathogenic properties, as well as sequence analysis, isolate designated as 4003/3 was identified as Fusarium graminearum deposited in NCBI gene bank under Acc. Number MK061542. To our knowledge F. graminearum as the causal agent of Hyssopus officinalis L. seed rot in Serbia was noticed for the first time.

Antifungal activity of plant essential oils and Pseudomonas chlororaphis strains against Cercospora beticola Sacc.

Leaf spot disease caused by Cercospora beticola Sacc. is the most destructive foliar disease of beet. Cercospora leaf spot is controlled primarily by fungicides because the non-chemical alternatives do not provide commercially viable control. One of the ways of reducing chemical application is the use of different essential oils (EOs) or antagonistic plant growth-promoting rhizobacteria (PGPB). This study evaluates several EOs and PGPB belonging to Pseudomonas chlororaphis as possible control agents of this pathogen. Antifungal properties were determined by in vitro microdilution method against five C. beticola monosporial isolates originated from the locality Brus, Serbia (53?53? N, 21?04?E and 429 m above sea level) using EOs from medicinal plants: Turkish pickling herb (Echinophora tenuifolia), oregano (Origanum vulgare), basil (Ocimum basilicum), and myrtle (Myrtus communis) obtained by a hydro-distillation method. All tested oils displayed some antifungal activity against the fungal isolates. Origanum vulgare EO demonstrated the strongest antifungal activity (MIC - 0.0055?0.0051mg/mL), Ocimum basilicum slightly lower (MIC - 0.075?0.045mg/mL), followed by Myrtus communis (MIC - 0.775?0.045 mg/ mL) and Echinophora tenuifolia (MIC - 7.75?4.5 mg/mL). Five tested P. chlororaphis strains exhibited some antagonistic effect against C. beticola. Overnight culture (ONC) of P. chlororaphis strain E65 induced the highest percentage of inhibition (75.8%), followed by N3 (72.0%). A cell-free supernatant (CFS) and the CFS treated with EDTA (CFS-EDTA) of these strains showed similar inhibition of 60.2 and 56.0%, and both strains suppressed C. beticola growth. P. chlororaphis strains M1 and K113 also reduced the fungal growth by 67-70% using ONC and between 48-57% using different CFS fractions. The strains L1 and B25 caused inhibition of 60% using ONC and 50% by CFS. The lowest inhibition (~40%) by CFS-EDTA and heat-treated cell-free supernatant (HT-CFS) was recorded for B25, which was used as a reference strain. The tested isolates of C. beticola were susceptible to all selected essential oils and P. chlororaphis strains E25, N3, M1, and K113 in vitro, making them a promising non-chemical control agent. It is recommended that these findings should be tested in field conditions.