In this study, we report genetic characterization of Orobanche cumana, the causal agent of sunflower wilting in Serbia. The genetic diversity of this parasitic plant in Serbia was not studied before. ...Random amplified polymorphic DNA (RAPD) markers and partial rbcL gene sequences analysis were used to characterize the O. cumana populations at the molecular level. While phylogenetic analyses of RAPD-PCR amplicons were performed using unweighted pair-group Method analyses, rbcL gene sequences were analyzed using neigbor joining method and minimum spanning tree. Molecular analyses of RAPD-PCR analysis revealed high genetic diversity of O. cumana populations which indicated high adaptive potential of this parasitic weed in Serbia. Further analyses of rbcL gene using minimum spanning tree revealed clear differences among diverse sections of Orobanche genus. Although this molecular marker lacked the resolution to display intrapopulation diversity it could be a useful tool for understanding the evolution of this parasitic plant. Our results suggested that O. cumana has great genetic potential which can lead to differentiation of more virulent races which is important for determining crop breeding strategies for their control.
Riparian areas experience strong invasion pressures worldwide and represent important points of spread for invasive alien plants (IAPs) in the European mainland. The Danube Basin is a well-known ...point of high plant invasion levels. Given that the middle part of the Danube Basin is critically understudied and the general lack of data for Serbia, the study aimed to provide an insight into the spatial patterns of plant invasions in the riparian areas of Serbia (Middle Danube Basin area). A total of 250 field sites, distributed along 39 rivers (nine catchment areas) and six canal sections, were studied during a four-year period (2013–2016) for the presence and abundance of IAPs. At the landscape scale, we studied distribution patterns of IAPs, differences in invasion levels in different catchment areas and between rivers and canals. At the local scale, we investigated how the proximity to roads/railway lines, housing areas, different land-use types (primarily agriculture), and dominant vegetation on site related to invasion patterns. Of the 26 studied IAPs, those with a well-known weedy behavior, long history of cultivation and strong affinity for riparian areas prevailed in the study area. Riparian zones of the Danube catchment exhibited the highest invasion levels in terms of IAPs richness and abundance, followed by the catchment areas of the Timok, Sava and Zapadna Morava rivers. Surprisingly, the Danube-Tisa-Danube canal network had the lowest invasion level. At the local scale, agriculture in proximity of the field site and dominant vegetation on site were observed as significant predictors of the invasion level. On the other hand, proximity to roads/railway lines and housing areas was not related to the invasion level. Finally, our study provides the first systematic overview of IAPs’ distribution data for riparian areas of the Middle Danube Basin in Serbia, which could provide a basis for long-term monitoring of IAPs and development of future management plans.
Ambrosia artemisiifolia (common ragweed) and A. trifida (giant ragweed) are
very important weed species that are invasive in Serbia and are often found
in agricultural regions. When these weeds are ...present at high densities, crop
yields can be significantly reduced or even completely destroyed. Unlike A.
artemisiifolia, A. trifida is locally present in the Central Backa region
(Vojvodina province), and it is expected that its area of distribution will
expand in the future. Starting from the assumption that future distribution
of A. trifida could take on larger proportions than now, the aim of this
study was focused on examining the interaction between these two species.
Experiments were conducted using the replacement design model, in which
Ambrosia trifida/Ambrosia artemisiifolia per m2, were planted as density
ratios of 10/0; 8/2; 4/6; 6/4; 2/8, and 0/10, in a completely randomized
block system with four replications. The vegetative parameters (height and
dry mass) of A. artemisiifolia were measured in July, August and September
over a period of two years (2016 and 2017), and the results were
statistically analysed in the Statistical Package for the Social Sciences
(SPSS 23). In July 2016, the average height of A. artemisiifolia was in the
range between 35.00 and 50.40 cm, in August it was from 68.00 to 95.50 cm,
and between 83.75 and 99.80 cm in September. In the following season (2017),
the corresponding values ranged from 56.19 to 78.50 (July), 98.38 to 125.50
cm (August) and 111.19 to 148.50 (September). An increase in the number of A.
artemisiifolia plants and decrease in A. trifida counts per m2 caused an
increase in the dry mass of A. artemisiifolia per plant. The dry mass of A.
artemisiifolia ranged from 4.22 to 6.11 g/plant (July), 8.96 to 10.27 g/plant
(August) and 7.04 to 19.53 g/plant (September). In the following season,
these values ranged from 9.62 to 14.60 g/plant, 14.37 to 28.90 g/plant, and
23.43 to 40.47 g/plant in July, August and September, respectively. Minimum
values of vegetative parameters were recorded in the treatment with 2 plants,
and maximum in the treatment with 10 A. artemisiifolia plants/m2. This means
that interspecific competition is more pronounced in this ragweed species
than intraspecific competition.
Agrotechnical measures are the main factor defining the vineyard weed flora
structure and composition, while adequate weed control measures
simultaneously ensure that vineyards are being ...well-managed, thus securing
good grapevine health and high quality of wine. Given that the biological
spectrum of weeds affects the choice of weed control measures, the aim of
this study was to determine the biological properties of the weed flora in
Vrsac vineyards, by assessing dominant life forms and phenology of the
identified weeds. The floristic analysis was conducted during the 2016
vegetation season (March-November) at 60 plots (1 m2), at three field sites.
The presence of 97 plant taxa, belonging to 26 families, was determined. The
biological spectrum of the vineyards weed flora has shown a
thero?phyto-hemicryptophyte character (therophytes: 57.73% and
hemicryptophytes: 34.02%). The scapose herbaceous plants with
summer-flowering phenology were dominant within the therophytes and
hemicryptophytes. The obtained results have shown a higher weed diversity in
vineyards, when compared to previous research of the weed flora in the study
area, but similar to more recent studies conducted in the neighbouring
countries. Furthermore, the dominant presence of therophytes in the vineyard
weed flora was expected, bearing in mind the primarily mechanical weed
control measures traditionally applied in vineyards.
Institutions of higher education address the challenges of globalization by increasing their internationalization. This paper addresses the issue of consumers’ decision-making in higher education, ...based on a literature review. The aim of this paper is to formulate a theoretical model, identifying and systematizing factors, influencing the high school graduates’ decision to study abroad. The proposed model consists of 114 factors, divided into six groups. The model allows the assessment of each factor and its influence on the student’s decision, as well as the assessment of the factors’ interactions. The model can be used by the stakeholders of the higher education system, as to define the policies and strategies of individual institutions.
Glyphosate may cause injury to non-target plants. The first detectable symptom after glyphosate treatment is the growth inhibition, followed by noticeable yellowing (chlorosis) of the treated tissue. ...Five to ten days after the treatment, the chlorosis turns into necrosis and the plants begin to die. Greenhouse research was conducted in 2007 to investigate the response of glyphosate resistant (GR) soybeans PAN 520 line and non-glyphosate resistant EGRET line of soybeans to glyphosate trimesium sulphosate and to evaluate soybeans injury to help in weed resistance detection. The methods used to detect changes were dose response test, HPLC measurement based on glyphosate induced accumulation of shikimate, and morpho-anatomical changes (light and electron microscopy). Damaged chloroplasts are a clear indication of a glyphosate injury. If the injury rating is related to increased shikimate levels, there is greater certainty that differences among biotypes are due to glyphosate tolerance.
The germination ecology of Ambrosia artemisiifolia and A. trifida glyphosate susceptible biotypes sampled in marginal areas, was compared with that of the same species but different biotypes ...suspected of glyphosate resistance, common and giant ragweed, respectively. The suspected resistant biotypes were sampled in Roundup Ready® soybean fields. Within each weed species, the seeds of the biotype sampled in marginal area were significantly bigger and heavier than those of the biotype sampled in the soybean fields. A. artemisiifolia biotypes exhibited a similar dormancy and germination, while differences between A. trifida biotypes were observed. A. artemisiifolia biotypes showed similar threshold temperature for germination, whereas, the threshold temperature of the susceptible A. trifida biotype was half as compared to that of the resistant A. trifida biotype. No significant differences in emergence as a function of sowing depth were observed between susceptible A. artemisiifolia and suspected resistant A. trifida biotype, while at a six-cm seedling depth the emergence of the A. artemisiifolia susceptible biotype was 2.5 times higher than that of the A. trifida suspected resistant biotype. This study identified important differences in seed germination between herbicide resistant and susceptible biotypes and relates this information to the ecology of species adapted to Roundup Ready® fields. Information obtained in this study supports sustainable management strategies, with continued use of glyphosate as a possibility.
Recent reports of the presence of Ambrosia trifida (AT) in areas infested by A. artemisiifolia (AA) in Serbia warn of the impending establishment of a more damaging crop weed. Here, we test the ...potential competitive effects of these two weed species. We conducted a field competition study in 2016 and 2017 as a replacement series experiment arranged in a split plot, with main plots (20.5 m × 2 m) at total plant densities of 10 and 100 plants/m2, and sub‐plots (3 m × 2 m) at the proportion of AT to AA of 100:0, 80:20, 60:40, 40:60, 20:80 and 0:100. Individual plant biomass (IPB) for AT was lowest when grown in monoculture, while AA reached its highest IPB in its monoculture. With AT < 40%, the AT IPB was larger than (2017) or the same as AA (2016). With AT > 40%, its IPB decreased due to increased intraspecific competition. We obtained the lowest sub‐plot biomass (SPB) of AT + AA in mixtures with 40:60 and 60:40 ratios, and also the highest SPB of other weed species. We show that despite a larger leaf area, AT may not fully replace AA and thus not become a new threat to crops, as it not only suffers from intraspecific competition at high densities, but also from interspecific competition with AA. Therefore, crops may benefit from a stable coexistence of both species as compared to highly dominant AT or AA. Further studies in the presence of crops are needed to confirm this hypothesis.
PDF
