Population dynamics of the species Plantago major L. and Poa annua L. in a replacement series experiment

Population dynamics of the species Plantago major L. and Poa annua L., typical representatives of ruderal vegetation, was analyzed in a replacement series experiment. The analyzed species were sown in an area with meadow vegetation, where the vegetation present had been previously removed by a total herbicide and additionally by hoeing. The objective of the experiment was to monitor growth dynamics and the effect of intra- and inter-specific interaction of the species Plantago major and Poa annua in conditions of different sowing densities and proportions. The effects of intra- and inter-specific interference and the density-dependent responses were assessed on the basis of several parameters (natality, mortality, age structure, and measures of ontogenetic changes). Based on the study results, it can be concluded that the responses of the species in the experiment were different, which is explained by different adaptive mechanisms, i.e., strategies, in the specific environmental conditions. An effect of the density dependent response was present in both species in the replacement series experiment. The response was amplified by water deficit caused by intensive evapora­tion of the bare soil. No effect of inter-specific interference was observed at the given densities of the study species on the sample plots. An effect of intra-specific interference of the species Plantago major and Poa annua was observed in the guise of a density-negative response of the rate of ontogenetic changes and fecundity

Uloga i značaj strategijskog budžetiranja za konkurentnost agrobiznis lanaca snabdevanja

Rapid challenges and changes that are an integral part of the business environment require from the enterprises to plan carefully their business, as well as to assess the probability of occurrence and outcome of future events. The importance of this approach is even more evident in the field of agribusiness, which is characterized by the increasingly unfavorable business conditions along with numerous specificities and limitations typical for agricultural activity. It is primarily about the growing business costs on one side and disproportionate changes in the level of agricultural products' selling prices on the other one. The enterprises form a supply chain in order to reduce risk and uncertainty, to realize the production of high-quality products at competitive prices, to maintain and increase the market share. The realization of such complex goals requires an adequate approach to the budgeting process. The aim of the paper is to highlight the importance, achievements and challenges of budgeting as an instrument of management accounting and strategic budget in order to support management in their efforts of acquiring and improving the competitiveness of the entire supply chain.Rapidni izazovi i promene koje su sastavni deo poslovnog ambijenta zahtevaju da preduzeća pažljivo planiraju svoje poslovanje, kao i da procene verovatnoću nastanka i ishod budućih događaja. Značaj navedenog pristupa još više dolazi do izražaja u domenu agrosektora koji, uz brojne specifičnosti i ograničenja svojstvena samoj poljoprivrednoj delatnosti, odlikuju i sve nepovoljniji uslovi poslovanja. Reč je pre svega o rastućim troškovima poslovanja s jedne i nesrazmerne promene u visini prodajnih cena poljoprivrednih proizvoda na drugoj strani. Preduzeća formiraju lanac snabdevanja kako bi redukovala rizik i neizvesnost, realizovala proizvodnju kvalitetnih proizvoda po konkurentnim cenama, očuvala i povećala tržišno učešće. Realizacija tako složenih ciljeva zahteva adekvatan pristup procesu budžetiranja. Cilj rada je da osvetli značaj, domete i izazove budžetiranja kao instrumenta upravljačkog računovodstva i strategijskog budžeta za potrebe podrške menadžmentu u naporima sticanja i unapređenja konkurentnosti čitavog lanca snabdevanja

Population dynamics of the species Plantago major L. and Poa annua L. in a replacement series experiment

Population dynamics of the species Plantago major L. and Poa annua L., typical representatives of ruderal vegetation, was analyzed in a replacement series experiment. The analyzed species were sown in an area with meadow vegetation, where the vegetation present had been previously removed by a total herbicide and additionally by hoeing. The objective of the experiment was to monitor growth dynamics and the effect of intra- and inter-specific interaction of the species Plantago major and Poa annua in conditions of different sowing densities and proportions. The effects of intra- and inter-specific interference and the density-dependent responses were assessed on the basis of several parameters (natality, mortality, age structure, and measures of ontogenetic changes). Based on the study results, it can be concluded that the responses of the species in the experiment were different, which is explained by different adaptive mechanisms, i.e., strategies, in the specific environmental conditions. An effect of the density dependent response was present in both species in the replacement series experiment. The response was amplified by water deficit caused by intensive evapora­tion of the bare soil. No effect of inter-specific interference was observed at the given densities of the study species on the sample plots. An effect of intra-specific interference of the species Plantago major and Poa annua was observed in the guise of a density-negative response of the rate of ontogenetic changes and fecundity.Istraživanja populacione dinamike tipičnih predstavnika ruderalne vegetacije (Plantago major L. i Poa annua L.) u eksperimentu zamenskih serija izvršena su u cilju praćenja dinamike rasta tipičnih kolonizatora u uslovima obrastanja 'praznog prostora', nastalog uklanjanjem vegetacije sa eksperimentalne površine, kao i odnosi unutar i između analiziranih vrsta koji se uspostavljaju u uslovima stalne narušenosti takvih površina permanentnim uklanjanjem ostalih vrsta. Na osnovu različitih populacionih parametara ustanovljene su razlike u dinamici i strategiji rasta ovih vrsta, kao i efekat intra- i interspecifičnih interakcija u definisanim uslovima inicijalnih gustina i proporcija sejanja.nul

Photosynthetic efficiency of Pedunculate oak seedlings under simulated water stress

Photosynthetic performance of seedlings of Quercus robur exposed to short-term water stress in the laboratory conditions was assessed through the method of induced fluorometry. The substrate for seedlings was clayey loam, with the dominant texture fraction made of silt, followed by clay and fine sand, with total porosity 68.2%. Seedlings were separated in two groups: control (C) (soil water regime in pots was maintained at the level of field water capacity) and treated (water-stressed, WS) (soil water regime was maintained in the range of wilting point and lentocapillary capacity). The photosynthetic efficiency was 0.642±0.25 and 0.522±0.024 (WS and C, respectively), which was mostly due to transplantation disturbances and sporadic leaf chlorosis. During the experiment Fv/Fm decreased in both groups (0.551±0.0100 and 0.427±0.018 in C and WS, respectively). Our results showed significant differences between stressed and control group, in regard to both observed parameters (Fv/Fm and T½). Photosynthetic efficiency of pedunculate oak seedlings was significantly affected by short-term water stress, but to a lesser extent than by sufficient watering

Photosynthetic efficiency of Pedunculate oak seedlings under simulated water stress

Photosynthetic performance of seedlings of Quercus robur exposed to short-term water stress in the laboratory conditions was assessed through the method of induced fluorometry. The substrate for seedlings was clayey loam, with the dominant texture fraction made of silt, followed by clay and fine sand, with total porosity 68.2%. Seedlings were separated in two groups: control (C) (soil water regime in pots was maintained at the level of field water capacity) and treated (water-stressed, WS) (soil water regime was maintained in the range of wilting point and lentocapillary capacity). The photosynthetic efficiency was 0.642±0.25 and 0.522±0.024 (WS and C, respectively), which was mostly due to transplantation disturbances and sporadic leaf chlorosis. During the experiment Fv/Fm decreased in both groups (0.551±0.0100 and 0.427±0.018 in C and WS, respectively). Our results showed significant differences between stressed and control group, in regard to both observed parameters (Fv/Fm and T½). Photosynthetic efficiency of pedunculate oak seedlings was significantly affected by short-term water stress, but to a lesser extent than by sufficient watering.U radu je analizirana fotosintetička efikasnost sadnica Quercus robur, izloženih kratkotrajnom vodnom stresu u laboratorijskim uslovima, metodom indukovane fluorimetrije. Kao supstrat za gajenje sadnica korišćena je glinovita ilovača, čiju je dominantnu teksturnu frakciju činio prah, zatim glina pa sitan pesak; totalne poroznosti 68,2%. Sadnice su bile podeljene u dve grupe: S (kontrolna grupa, kod kojih je vodni režim supstrata u saksijama održavan na nivou poljskog vodnog kapaciteta) i WS (grupa izložena vodnom stresu, kod kojih je vodni režim supstrata održavan između tačke venjenja i lentokapilarnog kapaciteta). Fotosintetička efikasnost iznosila je 0,642±0,258 kod kontrolnih sadnica, odnosno 0,522±0,0243 kod izloženih vodnom stresu, što je uglavnom bilo uzrokovano poremećajima izazvanim presađivanjem kao i pojavi hloroze na listovima. Tokom eksperimenta, vrednost Fv/Fm se smanjila u obe grupe sadnica (0,551±0,0100 kod C, odnosno 0,427±0,018 kod WS). U oba merenja utvrđene su statistički značajne razlike između stresirane i kontrolne grupe sadnica u pogledu ispitivanih parametara. Izlaganje sadnica hrasta lužnjaka kratkotrajnom vodnom stresu imalo je značajan uticaj na smanjenje fotosintetičke efikasnosti sadnica, ali u manjoj meri nego izlaganje sadnica obilnom zalivanju.Projekat ministarstva br. TD2005

Research on long-term colonization of goosander (Mergus merganser Linneaus, 1758) with reference to habitat availability

This article presents data on long-term colonization of goosander in Western Serbia and Eastern Republic of Srpska (on five oligotrophic reservoirs formed by the Drina River) based on continuous counting since the first observation of nesting in 1987. The total number of breeding pairs and their distribution in neighboring habitats continuously increased from year to year, suggesting that expansion of the population is still below the limit of the habitat. The decrease in population which occurred in certain years was due to environmental or anthropogenic influence.U ovoj studiji prikazani su podaci o dugotrajnoj kolonizaciji Mergus merganser L. u zapadnoj Srbiji i u istočnom delu Republike Srpske, i to na pet oligotrofnih jezera nastalih od reke Drine. Ukupan broj parova i njihova distribucija u okolnim staništima se kontinuirano povećava iz godine u godinu, što ukazuje na činjenicu da je ekspanzija te populacije još uvek ispod optimalnih granica koje dato stanište pruža. Pad brojnosti populacije tokom ranijih godina bio je uslovljen uticajem sredine ili antropogenim delovanjem.nul

Radiolitička sinteza i karakterizacija PVA/Au nanokompozita – uticaj pH rastvora

Nanokompoziti polimer - nanočestice plemenitih metala predstavljaju važnu grupu nanomaterijala. Njihova svojstava zavise kako od veličine nanopunioca, tako i od načina sinteze nanokompozita. U radu su radiolitički, gama zračenjem sintetisani koloidni rastvori PVA/Au, pri različitim pH vrednostima, od kojih su uparavanjem rastvarača dobijeni nanokompozitni filmovi. UV-Vis apsorpcioni spektri rastvora imaju karakterističnu plazmonsku apsorpciju nanočestica zlata na oko 520 nm. Vrednosti maksimuma apsorpcije su nelinearno zavisne od pH vrednosti rastvora. Talasna dužina maksimuma apsorpcije je najmanja za pH = 7, što teorijski odgovara česticama najmanje veličine. Dimenzije čestica su određene i XRD merenjima. Interakcija nanopunioca i matrice praćena je IC spektroskopijom, a termička stabilnost nanokompozita je ispitana TG analizom

Ekonomski efekti primene mašina i oruđa za uređenje zemljišta u proizvodnji suncokreta

The need of preservation and rational use of natural resources such is land requires the elimination of the usual practice of production and application of new technologies and new types of machines and tools. However, massive acceptation and successful application of new technologies and new types of machines and tools in practice requires certificates of manifestation the positive technical, technological and economic effects obtained through appropriate research. Bearing this in mind, the aim of this paper is to examine the economic effects of applying new technology and new types of machines and tools for the arrangement of soil's surface and depth in sunflower production. In this sense, conducted economic analysis shows that a change in technology and application of new types of machines and tools in sunflower production is economically justified, given that there is a reduction of variable costs per kilogram of produced sunflower by 4.77%. The research and results obtained in this analysis represent only the first phase of research of the economic effects of application of new types of machines and tools in crop production (in this case in sunflower production). The results indicate the need to expand research to other important crops.Potreba očuvanja i racionalnog korišćenja neobnovljivih prirodnih resursa, kao što je zemljište, zahteva eliminisanje uobičajene prakse proizvodnje i primenu novih tehnologija obrade i novih mašina i oruđa. Međutim, da bi nove tehnologije obrade i nove mašine i oruđa bili masovno prihvaćeni i uspešno primenjeni u praksi, potrebna je potvrda ispoljavanja pozitivnih tehničko-tehnoloških i ekonomskih efekata dobijena kroz odgovarajuća naučna istraživanja. Imajući to u vidu, cilj ovog rada je da se sagledaju ekonomski efekti primene nove tehnologije obrade i novih mašina i oruđa za uređenje zemljišta po površini i dubini u proizvodnji suncokreta. U tom smislu sprovedena ekonomska analiza pokazuje da je promena tehnologije obrade i primena novih mašina i oruđa u proizvodnji suncokreta ekonomski opravdana, s obzirom da dolazi do smanjenja varijabilnih troškova po kilogramu proizvedenog suncokreta za 4,77%. Obavljeno istraživanje i rezultati dobijeni u ovoj analizi predstavljaju samo prvu fazu u istraživanjima ekonomskih efekata primene mašina i oruđa za uređenje zemljišta po površini i dubini u proizvodnji pojedinih kultura (u ovom slučaju suncokreta). Dobijeni rezultati ukazuju na potrebu proširenja istraživanja i na druge značajne poljoprivredne kulture

Uticaj promene cene goriva na optimizaciju ukupnih troškova upotrebe poljoprivredne mehanizacije za obradu zemljišta

Serbian agricultural producers are facing currently with a large number of challenges that significantly influence their business activities. One of them is for sure a high fuel price. The recent fuel price increase has caused a lot of concern among agricultural producers regarding its impact on operating costs and farm profitability. However, those higher costs will probably reflect themselves onto direct reduction in profit in the short run because the producers' possibilities are limited as to the changes they can economically make. While no one knows with certainty what will happen in the future, the current developments on the world market as well as the analysts' estimates indicate that we are likely to see continued high diesel fuel prices. Bearing this in mind, the objective of this research is to emphasize an importance of the fuel price change for optimization of total operating costs of the tillage agricultural machinery, then to detect the most important factors influencing this change and finally to contribute successfully to the formulation of the answers on mentioned questions. The results of this study suggest that for an increase of the agricultural machinery utilization efficiency as well as for minimization of their operating costs, it is necessary to start making more adequate management decisions. This is certainly one of the safe ways for alleviation of the consequences caused by the high fuel price mostly influenced by the world fuel market trends.Poljoprivredni proizvođači u Srbiji suočavaju se sa velikim brojem izazova koji značajno utiču na njihovo poslovanje. Jedan od njih je svakako visoka cena goriva. Skorašnje povećanje cene goriva nateralo je mnoge od njih da se zapitaju kakav će to uticaj imati na troškove proizvodnje tj. kako će se odraziti na profitabilnost poslovanja gazdinstva. Ono što je izvesno je da će u kratkom roku, ovako visoka cena dovesti do smanjenja profita, zato što su mogućnosti vlasnika da u kratkom roku učine ekonomska prilagođavanja prilično limitirane. I dok niko sa sigurnošću ne može da pretpostavi šta će se dešavati u budućnosti, trenutna kretanja na svetskom tržištu i procene analitičara govore da i dalje treba očekivati održavanje cene na visokom nivou. Imajući to u vidu, cilj ovog istraživanja je da se ukaže na značaj promene cene goriva za optimizaciju ukupnih troškova upotrebe poljoprivredne mehanizacije za obradu zemljišta, da se otkriju najvažniji faktori koji na to utiču i da se sagleda njihov uticaj, uz nastojanje da se na taj način doprinese uspešnijem formulisanju odgovora na napred postavljena pitanja. Na osnovu dosadašnjih rezultata istraživanja može se konstatovati da je za povećanje efikasnosti korišćenja poljoprivredne mehanizacije i minimiziranje troškova njihove upotrebe, od presudnog značaja celishodno i blagovremeno sprovođenje adekvatnih mera iz oblasti menadžmenta. To je svakako jedan od sigurnih načina za ublažavanje posledica izazvanih visokom cenom goriva na čije formiranje prevashodni uticaj imaju kretanja na svetskom tržištu derivata