POLLEN VIABILITY IN QUINCE CULTIVARS

Pollen viability of eight quince cultivars (ʻLeskovackaʼ, ʻVranjskaʼ, ʻMoravaʼ, ʻPazardzijskaʼ, ʻHemusʼ, ʻAsenicaʼ, ʻPortugalʼ and ʻTriumphʼ), was studied in the two-year period (2011-2012). Testing of pollen viability was performed using two methods: the staining of pollen with acetocarmine (indirect method) and pollen germination in vitro with sucrose and agar-agar (direct method). Studied cultivars differed significantly in terms of pollen viability. The lowest percentage of stained pollen grains was detected in ʻLeskovackaʼ cultivar (70.29%) and the highest in the cultivars ʻAsenicaʼ, ʻHemusʼ and ʻTriumphʼ (over 90%). Similarly to that, the lowest percentage of pollen germination was obtained in ʻLeskovackaʼ cultivar (62.86%) and the highest in the cultivars ʻMoravaʼ, ʻAsenicaʼ, and ʻTriumphʼ (over 80%). With the exception of ʻPortugalʼ cultivar, the values of pollen viability determined by staining with acetocarmine were higher for 3-15% compared to the pollen germination in vitro. However, values obtained using these tho methods are highly positively correlated. On the basis of obtained results, the both methods can be recommended as reliable tests for pollen viability of quince, although priority should be given to the method of pollen germination in vitro, because it is more accurate. All tested cultivars are distinguished for high pollen viability, and can be successfully used as male parents in hybridization. In addition, they also can be recommended as a good pollenisers when are planting new quince orchards

Modeling of thermoelectric module operation in inhomogeneous transient temperature field using finite element method

This paper is the result of research and operation modeling of the new systems for cooling of cutting tools based on thermoelectric module. A copper inlay with thermoelectric module on the back side was added to a standard turning tool for metal processing. For modeling and simulating the operation of thermoelectric module, finite element method was used as a method for successful solving the problems of inhomogeneous transient temperature field on the cutting tip of lathe knives. Developed mathematical model is implemented in the software package PAK-T through which numerical results are obtained. Experimental research was done in different conditions of thermoelectric module operation. Cooling of the hot module side was done by a heat exchanger based on fluid using automatic temperature regulator. After the calculation is done, numerical results are in good agreement with experimental. It can be concluded that developed mathe-matical model can be used successfully for modeling of cooling of cutting tools

FIELD PERFORMANCE AND FRUIT QUALITY OF PRIMOCANE FRUITING RASPBERRY CULTIVARS GROWN IN SERBIA

The main focus of our study was to investigate differences in ripening time, vegetative and generative potential (number of canes per meter of hedgerow, cane height and diameter, number of fruiting laterals per primocane, yield per primocane and per meter of hedgerow) as well as fruit quality traits (fruit weight, index of fruit shape, number of drupelets per fruit, soluble solids content, total acids, total and inverted sugars, and sucrose content) in four newly introduced primocane fruiting raspberry cultivars (‘Erika’, ‘Paris’, ‘Versailles’, ‘Satine’) that are internationally competitive to both growers and marketers in the fresh markets. Studies were conducted at a commercial raspberry plantation located near Kraljevo (Serbia), in the period of 2015-2016. Results from this study showed that the average earliest harvest time was observed in ‘Versailles’ (11th August),whereas ‘Paris’ was the latest cultivar (10th September). Significantly higher cane height was registered in cvs. ‘Erika’ and ‘Paris’ (213 and 204 cm, respectively) in comparison to the two other tested cultivars. ‘Erika’ expressed the lowest values of all generative characteristics, while ‘Paris’ yielded much higher per primocane (840 g), followed by ‘Versailles’ (805 g). The latter one is also characterized by the highest average fruit weight (4.93 g) and the lowest level of soluble solids, total and inverted sugars (10.9%, 8.18% and 6.94%, respectively), whereas ‘Satine’ had significantly higher total acids content of the fruit (2.18%) compared to the rest cultivars. In general, cvs. ‘Versailles’ and ‘Paris’ demonstrated the best productivity and outer or inner fruit quality

PERFORMANCE OF DIFFERENT PHOTOVOLTAIC MODELS IN ENERGYPLUS ENVIRONMENT

Zero net energy building uses photovoltaic (PV) panels for electricity generation from solar energy. To calculate the annual electricity generation, the EnergyPlus software is used. The EnergyPlus software contains three models of PV panels: Simple, Equivalent One-Diode and Sandia. It is important to determine behavior of these models during calculation at different conditions. The objective of this paper is to compare the PV energy output of these models in EnergyPlus environment

THE USE OF PV IN NET-ZERO ENERGY BUILDINGS: CHALLENGES AND PERSPECTIVES

From 31 December 2020, all new buildings shall be nearly zero-net-energy consumption buildings (ZNEBs), according to the recast of the European Directive 2010/31/EU. In a Zero-net-energy buildings scenario, Photovoltaics (PV) is very suitable for generating energy, ‘on site’ and ‘at site’. This fact enlarges the perspective of use of PV from the architectural scale to a wider scale, including the space close to the building or even to the urban and landscape scale. The authors of this paper consider opportunities and challenges for the use of PV in ZNEBs and also perspectives for investigating the relationship between PV and ZNEBs