Distribution of zinc in vineyard areas treated with zinc containing phytopharmaceuticalsVesna Bukovac
, Danimir Kerin
, 2000, izvirni znanstveni članek
Opis: Zinc concentration in vineyard soil is, in general, increased markedly by the long term application of zinc containing fungicides. The most significant source of Zn are nowadays dithiocarbamate based fungicides, e.g. Antracol. The concentration of total zinc and EDTA and ammonium lactate (AL) extractable Zn in soils are evaluated together with the concentration of Zn in different inorganic fertilizers and in fungicides. the results of the study indicate in the observed vineyard areas a long term accumulation of zinc appears. The study was made in vineyards of Kalvarija and Meranovo (Maribor, Slovenia).
Ključne besede: zinc, dithiocarbamate, soil
Objavljeno: 18.08.2017; Ogledov: 3; Prenosov: 0
Polno besedilo (108,83 KB)
Comparison of methods for determination of polyphenols in wine by HPLC-UV/VIS, LC/MS/MS and spectrophotometryVesna Bukovac
, Matija Strlič
, Drago Kočar
, 2009, izvirni znanstveni članek
Opis: Phenolic antioxidants are usually grouped into flavonoids and non-flavonoids, according to their structure. With regard to the tannic character, phenolic antioxidants are further subdivided to tannic phenols and non-tannic phenols. Collectively, these compounds contribute to the high antioxidant capacity of wine.
In this work, we compare determination of gallic acid, catechin, epicatechin, resveratrol, quercetin, dihydrobenzoic acid, sinapic acid, vanillic acid, caffeic acid, chlorogenic acid, ferullic acid, ellagic acid, p-coumaric acid and caftaric acid in 141 wine samples using two liquid chromatographic methods and detection systems, i.e. with UV detection and mass-spectrometric detection. In addition, we applied the conventional Folin-Ciocalteu spectrophotometric method for determination of the total phenolic content in wine samples and compared the results with those obtained using the chromatographic methods.
Despite satisfactory correlations statistically significant differences between HPLC-UV/VIS and LC/MS/MS were established, which could be related to coelution not detectable with UV/VIS detectors. The correlations between results of the spectrophotometric method and sum of LC/MS/MS determinations are not satisfactory and are different for white, red, and rosé wines.
Ključne besede: food analysis, wine, antioxidants, chromatography
Objavljeno: 17.08.2017; Ogledov: 14; Prenosov: 0
Polno besedilo (185,67 KB)
Ekonomika pridelave in predelave sončnicMartina Friškič
, 2017, diplomsko delo/naloga
Opis: Sončnica spada v družino košarnic, nebinovk (Asteraceae). Za namen pridelovanja olja uporabljamo drobnozrnato sorto sončnic. V diplomskem delu je razvit tehnološko-ekonomski simulacijski model za pridelavo sončnic in za nadaljnjo predelavo sončničnih semen v hladno stiskano sončnično olje. V tehnološko-ekonomskem simulacijskem modelu so v okviru kalkulacije skupnih stroškov ocenjeni naslednji ekonomski parametri: skupni prihodek ali vrednost proizvodnje, skupni stroški, lastna cena, lastna cena z upoštevanimi ukrepi kmetijske politike, finančni rezultat in koeficient ekonomičnosti. Vhodni podatki za oceno ekonomike izhajajo iz prakse. Rezultat analize je pokazal, da je, glede na pridelavo sončnic in končnega pridelka (pridelek sončnic = 2.950 kg/ha semena) ekonomsko najugodnejša prodaja sončničnega semena (vrednost proizvodnje = 525,50 €, finančni rezultat FR = 162,29 € in koeficient ekonomičnosti Ke = 1,45). Predelava sončničnega semena v hladno stiskano olje rezultira z vrednostjo proizvodnje 405,93 €. Glede na finančni rezultat in koeficient ekonomičnosti je ugodnejša prodaja hladno stiskanega sončničnega olja (finančni rezultat FR = 190,27 € in koeficient ekonomičnosti Ke = 1,88).
Ključne besede: Tehnološko-ekonomski model, ekonomika, sončnice, sončnično olje
Objavljeno: 08.08.2017; Ogledov: 16; Prenosov: 3
Polno besedilo (931,22 KB)
Antibacterial and anticandidal activity of Tylosema esculentum (marama) extractsWalter Chingwaru
, Gyebi Duodu
, Yolandi Van Zyl
, Runner Majinda
, Sam Yeboah
, Jose Jackson
, Petrina Kapewangolo
, Avrelija Cencič
, 2011, izvirni znanstveni članek
Opis: Bean and tuber extracts of Tylosema esculentum (marama) – an African creeping plant – were obtained using ethanol, methanol and water. Based on information that T. esculentum is used traditionally for the treatment of various diseases, the antibacterial and anticandidal effects of tuber and bean extracts were investigated. The antimicrobial activity of the extracts was tested on methicillin-resistant Staphylococcus aureus (MRSA, ATCC 6538), Mycobacterium terrae (ATCC 15755), Corynebacterium diphtheriae (clinical) and Candida albicans (ATCC 2091). We performed the broth microdilution test for the determination of the minimum inhibitory concentration (MIC) and a method to determine survival of microorganisms after in vitro co-incubation with the highest concentrations of T. esculentum extracts, followed by assessment of colony counts. Ethanol and methanol (phenolic) bean extracts exhibited higher potency against bacteria and yeast than aqueous extracts. Marama bean seed coat crude ethanolic extract (MSCE) and seed coat polyphenolic fractions, especially soluble-bound fraction (MSCIB), were highly antimicrobial against M. terrae, C. diphtheriae and C. albicans. All marama bean polyphenolic fractions, namely cotyledon acidified methanol fraction (MCAM), seed coat acidified methanol fraction (MSCAM), cotyledon insoluble-bound fraction (MCIB), seed coat insoluble-bound fraction (MSCIB), cotyledon-free polyphenolic fraction (MCFP) and seed coat free polyphenolic fraction (MSCFP) had high antimicrobial effects as shown by low respective MIC values between 0.1 mg/mL and 1 mg/mL. These MIC values were comparable to those of control antimicrobials used: amphotericin B (0.5 mg/mL) and cesfulodin (0.1 mg/mL) against C. diphtheriae, streptomycin (1.0 mg/mL) and gentamicin (0.4 mg/mL) against M. terrae, and amphotericin B (0.05 mg/mL) against C. albicans. Marama seed coat soluble-esterified fraction (MSCS) had closer activity to that of cefsulodin against M. terrae. High amounts of phenolic substances, such as gallic acid, especially in the seed coats, as well as high amounts of phytosterols, lignans, certain fatty acids and peptides (specifically protease inhibitors) in the cotyledons contributed to the observed antibacterial and anticandidal activities. Marama extracts, especially phenolic and crude seed coat extracts, had high multi-species antibacterial and anticandidal activities at concentrations comparable to that of some conventional drugs; these extracts have potential use as microbicides.
Ključne besede: marama, Tylosema esculentum, antibacterial activity, anticandidal activity
Objavljeno: 07.08.2017; Ogledov: 15; Prenosov: 3
Polno besedilo (1,38 MB)
Viral infections in queen bees (Apis mellifera carnica) from rearing apiariesAleš Gregorc
, Tamás Bakonyi
, 2012, izvirni znanstveni članek
Opis: Viral infection could have an impact on the success of queen rearing and a potential effect on reduced queen quality. Newly mated honey bee (Apis mellifera carnica) queens were collected from mating nuclei in queen rearing operations in Slovenia. Altogether, 81 queens were sampled from 27 rearing apiaries in 2006 and 72 queens from 24 apiaries in 2008. Queens were analysed for the presence of four viruses: acute bee paralysis virus (ABPV), black queen cell virus (BQCV), sacbrood virus (SBV) and deformed wing virus (DWV) by using reverse transcription polymerase chain reaction (RT-PCR). In 2006, 12%, 9% and 1% prevalence was found for ABPV, DWV and SBV, respectively; BQCV was not detected. Two years later, DWV, BQCV, SBV and ABPV were detected in 58%, 24%, 11% and 10% bee queens, respectively. In 2006, fourteen out of twenty-seven apaiaries were virus free, whereas in 2008 only three out of twenty-four apiaries were virus free. This is the first evidence of virus infection occurring in newly mated queens from mating nuclei in rearing apiaries. The possible impacts of queen rearing technology and epidemiological influences on virus infection are discussed in this study.
Ključne besede: queen bees, black queen cell virus, acute bee paralysis virus, sacbrook virus, deforming wing virus
Objavljeno: 04.08.2017; Ogledov: 32; Prenosov: 0
Polno besedilo (393,61 KB)
Combating Varroa destructor in honeybee colonies using flumethrin or fluvalinateAleš Gregorc
, Maja Ivana Smodiš Škerl
, 2007, izvirni znanstveni članek
Opis: Mite mortality in two apiaries, one with 32 and the other with 15 honeybee (Apis mellifera carnica) colonies, was recorded prior to and after flumethrin or fluvalinate treatments and after a control, oxalic-acid application. During the 42- and 51-day pre-treatment periods, the average daily natural mite drop was 0.04 (± 0.04) and 2.82 (± 2.19), respectively, which represents 1.09% (± 1.06) and 3.84% (± 3.04) of the total number of mites found during the experiment. The flumethrin or fluvalinate applications resulted in an average mite mortality at the two apiaries of 214.46 (± 260.02) and 4,098.64 (± 2,508.31). The treatments resulted in a 19.11% (± 14.62) and a 39.28% (± 10.47) reduction in the number of mites in slightly infested colonies and 94.30% (± 4.26) and 96.24% (± 3.14) in highly infested colonies. The difference in treatment efficacy between both apiaries was significant (P < 0.001) and indicates that fluvalinate and flumethrin are highly efficacious in dealing with highly infested honeybee colonies with sealed brood. The importance of effective mite control in colonies with a high level of natural mite mortality is discussed in this study.
Ključne besede: Acaricides, control methods, Apis mellifera, oxalic acid, mite infestation
Objavljeno: 04.08.2017; Ogledov: 32; Prenosov: 0
Polno besedilo (149,12 KB)
Primerjava števila in skupne mase deževnikov v različnih pridelovalnih sistemih po spravilu soje in ajdeLucija Jelenko
, 2017, diplomsko delo/naloga
Opis: Deževniki so pomemben del živega sveta v tleh in so indikatorji rodovitnosti tal. Na njihovo število in maso ima vpliv način kmetijske pridelave, kar smo preučevali na trajnostnem poskusu, ki poteka na Fakulteti za kmetijstvo in biosistemske vede od leta 2007. Pri štirih pridelovalnih sistemih (ekološkem, biodinamičnem, konvencionalnem, integriranem) in kontrolnem obravnavanju smo oktobra 2015 po spravilu soje in ajde analizirali število in maso deževnikov. Število malih, srednje velikih in velikih deževnikov, skupno število in skupna masa so po spravilu soje v povprečju 100-krat večji v primerjavi z ajdo. Na površini 0,25 m2 je bila največja skupna masa deževnikov pri soji v ekološkem (24,4 g/ 0,25 m2), pri ajdi pa v biodinamičnem pridelovalnem sistemu (14,2 g/ 0,25 m2). Skupno število deževnikov je bilo pri soji (26,0), kot tudi pri ajdi (17,9) največje v ekološkem pridelovalnem sistemu. Najmanjša skupna masa je bila pri soji v integriranem (6,9 g/ 0,25 m2), pri ajdi pa v integriranem, konvencionalnem pridelovalnem sistemu in kontrolnem obravnavanju (1,8 g/ 0,25 m2). Najmanjše skupno število je bilo pri soji v kontrolnem obravnavanju (13,1), pri ajdi pa v konvencionalnem pridelovalnem sistemu (3,8). Skupno število in skupno maso smo preračunali tudi v kg/ha in št. deževnikov/ha. Rezultati so potrdili hipoteze o vplivu pridelovalnih sistemov in različnih poljščin na število in maso deževnikov v tleh.
Ključne besede: deževniki, masa, število, ajda, soja, pridelovalni sistem
Objavljeno: 25.07.2017; Ogledov: 33; Prenosov: 13
Polno besedilo (896,23 KB)
Regulation of metabolic changes in shredded cabbage by modified atmosphere packagingAndrej Plestenjak
, Tomaž Požrl
, Janez Hribar
, Tatjana Unuk
, Rajko Vidrih
, 2008, izvirni znanstveni članek
Opis: The influence of different storage conditions on the storability of packaged shredded cabbage has been studied. The cabbage cultivar Fieldrocket was cut and packaged in glass jars and in polyethylene (PE) or polypropylene (PP) film. Several initial atmospheres were established within the packaged cut cabbage: 100 % N2, 5 % O2/95 % N2, 10 % O2/90 % N2, normal atmosphere (NA), 70 % O2/30 % N2 and 100 % O2. Samples were stored at two different temperatures of 0 and 10 °C for 7 days. Variation in CO2 and O2 concentrations was higher at 10 °C compared to 0 °C and the highest at the atmosphere consisting of 70 % O2/30 % N2. A decrease of O2 below 3–5 % and an increase of CO2 above 2–5 % in the packed product resulted in the appearance of anaerobic metabolism. An initial atmosphere consisting of 100 % O2, and a storage temperature of 0 °C resulted in delayed anaerobic metabolism compared to other atmospheric conditions and storage temperature of 10 °C. Rinsing of fresh cut cabbage also resulted in lower accumulation of acetaldehyde and ethanol. A higher variation in CO2 and O2 concentrations, and consequent accumulation of anaerobic metabolites had a negative influence on the sensorial properties of the cut cabbage. The higher permeability of PE film compared to PP and glass enabled faster exchange of CO2 and O2, which resulted in lower accumulation of anaerobic metabolites. However, a higher O2 concentration had a negative influence on the colour of fresh-cut cabbage. The best results were achieved by packing the fresh-cut cabbage in PE film with an initial atmosphere of 100 % O2 and stored at 0 °C.
Ključne besede: cabbage, modified atmosphere, packaging, polyethylene, polypropylene, respiration, anaerobic metabolism
Objavljeno: 24.07.2017; Ogledov: 42; Prenosov: 0
Polno besedilo (156,50 KB)
Prediction of standard lactation curves for primiparous Holstein cows by using corrected regression modelsJanez Jeretina
, Drago Babnik
, Dejan Škorjanc
, 2015, izvirni znanstveni članek
Opis: Prediction of the expected milk yield is important for the management of the primiparous cows (PPC) with a few or no data on their own milk productivity. We developed a system of regression equations for predicting milk yields in standard lactation. The models include the systematic effects of the calving season, the five-year rolling herd average of milk yield of PPC, the breeding values of the parents for milk production, and daily milk recordings. A total of 21,901 lactations of Holstein PPC were collected during the regular monthly milk recordings of cows in the Republic of Slovenia. By including daily milk recordings in the model, the coefficients of determination of regression models for the prediction of milk yield increase: without known recordings (M0) R 2 =0.80; with one recording (M1) R 2 =0.82; with two first consecutive recordings (M2) R 2 =0.86; and with three recordings (M3) R 2 =0.89. Deviations of milk yield up to 500 kg in a standard lactation (<1.6 kg/day) were as follows: with the model M0, they occurred in 53.4% of PPC; with M1, they occurred in 56.3% of PPC; with M2, they occurred in 64.5% of PPC; and with M3, they occurred in 70.9% of PPC. We concluded that the developed system of regression models is an appropriate method for milk yield prediction of PPC.
Ključne besede: primiparous cows, milk yield, prediction, lactation curves, regression equations
Objavljeno: 24.07.2017; Ogledov: 26; Prenosov: 1
Polno besedilo (497,85 KB)
An attempt to predict conformation and fatness in bulls by means of artificial neural networks using weight, age and breed composition informationMaja Prevolnik
, Marjana Novič
, Marjeta Čandek-Potokar
, Martin Škrlep
, Maria Font-I-Furnols
, 2015, izvirni znanstveni članek
Opis: The present study aimed to predict conformation and fatness grades in bulls based on data available at slaughter (carcass weight, age and breed proportions) by means of counter-propagation artificial neural networks (ANN). For chemometric analysis, 5893 bull carcasses (n=2948 and n=2945 for calibration and testing of models, respectively) were randomly selected from the initial data set (n≈27000; one abattoir, one classifier, three years period). Different ANN models were developed for conformation and fatness by varying the net size and the number of epochs. Tested net parameters did not have a notable effect on models’ quality. Respecting the tolerance of ±1 subclass between the actual and predicted value (as allowed by European Union legislation for on-spot checks), the matching between the classifier and ANN grading was 73.6 and 64.9% for conformation and fatness, respectively. Success rate of prediction was positively related to the frequency of carcasses in the class.
Ključne besede: govedo, goveje meso, mastnost mesa, struktura mesa, klavna teža, ANN modeli, modeli za napovedovanje
Objavljeno: 24.07.2017; Ogledov: 22; Prenosov: 0
Polno besedilo (1,12 MB)