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Yield performance and agronomic efficiency in oil pumpkins (Cucurbita pepo L. group Pepo) depending on production systems and varieties
Manfred Jakop, Silva Grobelnik Mlakar, Martina Bavec, Martina Robačer, Tjaša Vukmanič, Urška Lisec, Franc Bavec, 2017, izvirni znanstveni članek

Opis: In 2013 and 2014, a long-term trial (which was established in 2007) was conducted at the University Agricultural Centre in Pivola near Hoče. It included different production systems (conventional, integrated, organic, biodynamic), carried out in a field trial with oil pumpkins. The aim of the research was to analyse the effects of different production systems, varieties (hybrid and population variety) and years of production, on formation of oil pumpkin yields. The agricultural practice has been carried out in accordance with the applicable legislations and standards for the individual production system. When sowing, before fertilizing with nitrogen in early June and after the harvest, the amount of soil mineral nitrogen was monitored. We evaluated the number and weight of harvestable, unripe and decayed fruits, and yield of oil seed pumpkins and calculated the agronomic efficiency of the applied nutrients. The results showed that the year of production, the production system and the variety have a significant effect on some fruit characteristics and the yield of oil pumpkin seeds. The content of soil mineral nitrogen in May and September was significantly influenced by the production system and the year. In June, only the production system had a significant effect. The hybrid significantly increased the yields of oil pumpkin seeds in all production systems, even in the year that was less suitable for production. The agronomic efficiency of the applied nutrients in the biodynamic and organic production system is higher or equal than in the conventional production system, similarly, agronomic efficiency is higher in the hybrid compared to the oldest population variety efficiently. A comparable oil pumpkin yield can be expected in biodynamic and organic production, when proper nutrition and well carried out cultivation practices are combined with a new variety, when compared to less sustainable production systems, which often cause damage to the environment.
Ključne besede: production systems, variety, oil pumkins, mineral nitrogen, agronomic efficiency, yield
Objavljeno: 10.10.2018; Ogledov: 1168; Prenosov: 272
.pdf Celotno besedilo (290,91 KB)
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Combining ability and breeding potential of oilseed rape advanced lines for some of important quantitative traits
Valiollah Rameeh, 2017, izvirni znanstveni članek

Opis: Information on estimates of combining ability of the promising lines of breeding material is important for evolving higher yielding varieties of oilseed rape (Brassica napus L.). An experiment was conducted to quantitatively examine the genetic parameters of phenological traits, plant height, pods on main raceme, pods per plant and seed yield for eight oilseed rape genotypes using a half-diallel crosses. The result of the diallel analysis revealed significant mean squares of general and specific combining abilities (GCA and SCA) for all studied traits, indicating the importance of additive and non-additive genetic effects for these traits. On the other hand estimation of high narrow-sense heritability estimates for days to flowering, duration of flowering and pods on main raceme, indicated the prime importance of additive genetic effects for these traits. L420 and L401 with significant negative GCA effects for days to flowering and days to maturity were suitable for yielding early maturity combinations. L41, Zafar and L22 with significant positive GCA effects for seed yield were superior parents for increasing seed yield. The crosses with significant positive SCA effects for seed yield had at least one parent with significant positive GCA effects for this trait. The crosses including L41×L22, L41×LF2, Zafar×L22 and Zafar×L420 with seed yield of 3421.7, 3400, 3348.1 and 3311.3 kg ha-1 could be promising for determination of superior recombinants for high seed yield coupled with other growth characters in advanced generations of segregation.
Ključne besede: additive genetic effects, Brassica napus, degree of dominance, combining ability, heritability, oilseed rape, yield
Objavljeno: 10.10.2018; Ogledov: 643; Prenosov: 234
.pdf Celotno besedilo (276,21 KB)
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Rheological properties of marine sediments from the port of Koper
Jasna Smolar, Matej Maček, Ana Petkovšek, 2016, izvirni znanstveni članek

Opis: Subaqueous, fine-grained, cohesive sediments are continuously fluidized by waves and other disturbances that cause their movement, which can be described with numerical models incorporating rheological parameters. The rheological behaviour depends on the soil (solid) type, the volume concentration, the salinity and the testing methods. In this study, rheological investigations of marine sediments from the Port of Koper were carried out by using two coaxial cylinder rheometers (DV3T HB, Brookfield and ConTec Viscometer 5). The influence of the specimen volume, the size of the gap and the type of measuring spindles were analysed and compared. The measured data were evaluated using the Bingham model. For each data set, the boundary between the sheared (“fluid”) and the un-sheared (“solid”) material was calculated and then the calculated boundary was used instead of the outer radius of the cylinder for the evaluation of the rheological parameters, where necessary. A good comparison of the results was found when using this approach. The results are also in agreement with the literature data. The ConTec Viscometer 5, primarily designed for mortars and concrete, was shown to be also suitable for the investigation of sediments.
Ključne besede: marine sediments, Bingham model, yield stress, plastic viscosity, coaxial cylinder rheometer, plug flow, Bay of Koper
Objavljeno: 18.06.2018; Ogledov: 493; Prenosov: 43
.pdf Celotno besedilo (709,57 KB)
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Yielding in the isotropic compression of Porto silty sand
Miguel Ferreira Amaral, Sara Rios, António Viana da Fonseca, 2012, izvirni znanstveni članek

Opis: The yielding locus of a well-graded silty sand was analysed by means of isotropic compression tests and scanning electron microscopy (SEM). The tests were performed with precise instrumentation, for internal and external strain measurements, and shear-wave velocity measurements by means of bender elements. Finally, aiming at an accurate evaluation of the yield stress, four different methods were applied – two quite well know and the other two being innovative – leading to interesting conclusions.
Ključne besede: silty sand, yield point, isotropic compression, high pressure, seismic waves
Objavljeno: 13.06.2018; Ogledov: 397; Prenosov: 54
.pdf Celotno besedilo (613,18 KB)
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The effect of late autumn cutting of lucerne (Medicago sativa L.) on the growth rhythm of the first cut in the following year
Miran Podvršnik, Anastazija Gselman, 2016, izvirni znanstveni članek

Opis: The field experiment aimed at determination of influence of autumn harvest on rhythm of the growth of lucerne (Medicago sativa L.) and yield quality of the first cut in the following year was carried out in Spodnji Gabernik (258 m above sea level, 46°15′54.94″ N and 15°34′6.05″ E), in the fourth growth year of the lucerne variety ‘Soča’. The experiment was designed as a randomized block in four replications. The individual treatments represented weekly autumn cuttings (1) 24/9/2014, (2) 01/10/2014, (3) 08/10/2014, (4) 15/10/2014 and (5) 22/10/2014. The paper presents data associated with the amount of lucerne dry matter yield (DMY) per treatment compared with the DMY of the first spring cut in the year 2015 (18/05/2015). The growth rhythm of lucerne in each treatment, which took place before the first cut in year 2015, was based on the measurements of the height of the plants. The yield quality was evaluated by NIRS method for determination of crude protein (CP), the net energy of lactation (NEL) and metabolic energy (ME) in dry samples regarding to DMY of each treatment. In autumn 2014, statistically significant higher dry matter yields were obtained in later harvested treatments (5 and 4). Similarly, in spring 2015 the trend of higher crop dry matter yield was observed in treatments harvested later in the autumn of 2014. However, the differences were not significant. Statistically significant differences between treatments were acquired within CPY, NELY and MEY. Before the first mowing, in spring 2015, statistically significant trend of higher plants was also detected in treatments with later cutting in 2014.
Ključne besede: Medicago sativa, cutting regime, growth rhythm, dry matter yield
Objavljeno: 14.11.2017; Ogledov: 1089; Prenosov: 316
.pdf Celotno besedilo (346,98 KB)
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Impact of various types of anti-hail nets on light exposure in orchards and quality parameters of apples
Marinka Brglez Sever, Stanislav Tojnko, Tatjana Unuk, 2015, pregledni znanstveni članek

Opis: The new Common Agricultural Policy (CAP) has been designed to shrink funds that Hungarian agricultural reform will in Nowadays, anti-hail nets are a part of basic equipment in a modern apple orchards. They decrease the risks of apple production and thus allow regular and quality apple harvest. Colours of nets differently obstruct the passing of light through the net, which directly affects some quality parameters of the yield, especially the fruit skin colour. The article includes a brief overview of studies associated with the impact of light exposure under different types of anti-hail nets on quality of apple fruits, as well as investigations which deal with adaptation of various technological measures, such as the use of reflective ground foil. A part of data from the existing literature explains the effect of anti-hail net usage on forming a microclimate under the net, and consequently, its effect on the development and dynamics of diseases and pests.
Ključne besede: anti-hail net, light, microclimate, apples, yield quality
Objavljeno: 14.11.2017; Ogledov: 713; Prenosov: 82
.pdf Celotno besedilo (173,10 KB)
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Testing the performance of cubic splines and Nelson-Siegel model for estimating the zero-coupon yield curve
Eva Lorenčič, 2016, izvirni znanstveni članek

Opis: Understanding the relationship between interest rates and term to maturity of securities is a prerequisite for developing financial theory and evaluating whether it holds up in the real world; therefore, such an understanding lies at the heart of monetary and financial economics. Accurately fitting the term structure of interest rates is the backbone of a smoothly functioning financial market, which is why the testing of various models for estimating and predicting the term structure of interest rates is an important topic in finance that has received considerable attention for many decades. In this paper, we empirically contrast the performance of cubic splines and the Nelson-Siegel model by estimating the zero-coupon yields of Austrian government bonds. The main conclusion that can be drawn from the results of the calculations is that the Nelson-Siegel model outperforms cubic splines at the short end of the yield curve (up to 2 years), whereas for medium-term maturities (2 to 10 years) the fitting performance of both models is comparable.
Ključne besede: Cubic splines, Nelson-Siegel, yield curve, zero-coupon bonds, term structure of interest rates
Objavljeno: 14.11.2017; Ogledov: 826; Prenosov: 279
.pdf Celotno besedilo (751,46 KB)
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A new somatic cell count index to more accurately predict milk yield losses
Janez Jeretina, Dejan Škorjanc, Drago Babnik, 2017, izvirni znanstveni članek

Opis: Intramammary infection and clinical mastitis in dairy cows leads to considerable economic losses for farmers. The somatic cell concentration in cow's milk has been shown to be an excellent indicator for the prevalence of subclinical mastitis. In this study, a new somatic cell count index (SCCI) was proposed for the accurate prediction of milk yield losses caused by elevated somatic cell count (SCC). In all, 97238 lactations (55207 Holstein cows) from 2328 herds were recorded between 2010 and 2014 under different scenarios (high and low levels of SCC, four lactation stages, different milk yield intensities, and parities (1, 2, and _>3). The standard shape of the curve for SCC was determined using completed standard lactations of healthy cows. The SCCI was defined as the sum of the differences between the measured interpolated values of the natural logarithm of SCC (ln(SCC)) and the values for the standard shape of the curve for SCC for a particular period, divided by the total area enclosed by the standard curve and upper limit of ln(SCC)=10 for SCC. The phenotypic potential of milk yield (305-day milk yield - MY305) was calculated using regression coefficients estimated from the linear regression model for parity and breeding values of cows for milk yield. The extent of daily milk yield loss caused by increased SCC was found to be mainly related to the early stage of lactation. Depending on the possible scenarios, the estimated milk yield loss from MY305 for primiparous cows was at least 0.8 to 0.9 kg day -1 and for multiparous cows it ranged from 1.3 to 4.3 kg day-1. Thus, the SCCI was a suitable indicator for estimating daily milk yield losses associated with increased SCC and might provide farmers reliable information to take appropriate measures for ensuring good health of cows and reducing milk yield losses at the herd level.
Ključne besede: dairy cows, milk production, lactation intervals, milk yield losses, somatic cell count index
Objavljeno: 24.10.2017; Ogledov: 905; Prenosov: 406
.pdf Celotno besedilo (317,33 KB)
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Prediction of standard lactation curves for primiparous Holstein cows by using corrected regression models
Janez 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: 718; Prenosov: 409
.pdf Celotno besedilo (497,85 KB)
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Intelligent system for prediction of mechanical properties of material based on metallographic images
Matej Paulič, David Močnik, Mirko Ficko, Jože Balič, Tomaž Irgolič, Simon Klančnik, 2015, izvirni znanstveni članek

Opis: This article presents developed intelligent system for prediction of mechanical properties of material based on metallographic images. The system is composed of two modules. The first module of the system is an algorithm for features extraction from metallographic images. The first algorithm reads metallographic image, which was obtained by microscope, followed by image features extraction with developed algorithm and in the end algorithm calculates proportions of the material microstructure. In this research we need to determine proportions of graphite, ferrite and ausferrite from metallographic images as accurately as possible. The second module of the developed system is a system for prediction of mechanical properties of material. Prediction of mechanical properties of material was performed by feed-forward artificial neural network. As inputs into artificial neural network calculated proportions of graphite, ferrite and ausferrite were used, as targets for training mechanical properties of material were used. Training of artificial neural network was performed on quite small database, but with parameters changing we succeeded. Artificial neural network learned to such extent that the error was acceptable. With the oriented neural network we successfully predicted mechanical properties for excluded sample.
Ključne besede: artificial neural network, factor of phase coherence between the surfaces, fracture toughness, image processing, mechanical properties, metallographic image, ultimate tensile strength, yield strength
Objavljeno: 12.07.2017; Ogledov: 743; Prenosov: 343
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