Branka Ljevnaić-Mašić

Nutrient removal by Phragmites australis (Cav.) Trin. ex Steud. In the constructed wetland system

AbstractsSignificant results are achieved with the use of semiaquatic vegetation for purification of municipal wastewater as well as other types of waste waters. The first constructed system for purification of municipal wastewater was made at the end of 1970s years in the United Kingdom, with semiaquatic plants playing the role of phytoremediation plants. In Serbia, municipal waste water purification based on constructed wetland system method was applied for the first time in the village of Glo an near Novi Sad and it was put in operation in 2004. The recipient of purified municipal wastewater has been the Danube River. Biological factors in this anthropogenic ecosystem are emergent plants, with dominance of the common reed. This emergent plant with its roles in phytofiltration and phytoaccumulation positively influences the quality of waters finally discharged into the Danube. The paper presents the results of nutrients (N, P, K), organic matter and total ash contents in dry matter of dominant plant species Phragmites australis (Cav.) Trin. ex Steud. in Glo an constructed wetland system in the period from 2004 to 2007.

Vegetation of the Hydrochari-Lemnete and Potametea classes in the Danube-Tisza-Danube hydrosystem (Serbia)

Aquatic vegetation of Hydrochari-Lemnetea and Potametea classes in the Danube-Tisza-Danube hydrosystem (Hs DTD) was studied in 2009–2012, by applying the standard Braun-Blanquet method. The canal network vegetation comprises 14 associations, with Trapetum natantis and Ceratophylletum demersi being the most widely distributed. Hs DTD is also a habitat for several important endangered species, which serve as edificators of the following phytocenoses: Nymphaeetum albae, Nymphaeetum albo-luteae, Nymphoidetum peltatae, Trapetum natantis, Lemno-Spirodeletum, Salvinio-Spirodeletum polyrrhizae, Lemno-Utricularietum vulgaris, Potametum nodosi, Myriophyllo-Potametum and Najadetum marinae. In the studied vegetation, we also found an invasive phytocenosis Elodeetum canadensis that did not have an expanding tendency, and Ceratophyllo demersi-Vallisnerietum spiralis that had this tendency, which made monitoring its stands necessary. Physico-chemical analyses of water, conducted at localities in which the studied phytocenoses thrive, revealed that the development and distribution of most phytocenoses is closely linked with specific habitat conditions. Among the studied parameters, the most significant for the phytocenoses differentiation were: pH, alkalinity, COD-MnO4, BOD5, NO3−, NO2−, PO43− and the concentration of total phosphorus.

Impact of climate changes on aquatic vegetation of hydromeliorative facilities

Distributions of 20 aquatic associations in the Danube-Tisza-Danube hydrosystem were mapped using published data and personal field observations resulting in 562 georeferenced collection sites. The Maxent modeling software was used to estimate the current potential and future distribution of the associations by the year 2050 (2xCO2 climate conditions, CCM3 model). Based on the Principal Component Analysis (PCA), climate data at the collection sites described climatic preferences of different aquatic associations. The central-eastern part of the investigated area showed the most favorable climatic conditions for aquatic vegetation growth and thus the highest potential for future biodiversity. The stands of Lemnetum trisulcae, Ceratophyllo-Azolletum filiculoides, Najadetum marinae, Salvinio natantis-Spirodeletum polyrhizae, Elodeetum canadensis and Potametum denso-nodosi associations displayed a marked invasive potential in the forecasted distribution scenarios. The results revealed that the stands of Nymphaeetum albae and Nymphaeo albae-Nupharetum luteae subass. nupharetosum associations are likely to be significantly less abundant in the future. As the key climatic factors used in the analysis were annual mean temperature, as well as mean temperature of the wettest and warmest quartile, the findings suggest that, if adequate protective measures shall not be taken, these provenances could become degraded in the next decade and some could even become extinct at the locations where they presently occur naturally.

Weed Flora in Organic Common Mallow (Malva sylvestris L.)

Summary The aim of this study was to examine weed flora occurring in an organic common mallow (Malva sylvestris L.), a newly established crop at the experimental field Bački Petrovac, Institute of Field and Vegetable Crops, Novi Sad, during the growing season of 2014. The weed flora consisted of six species, with even a half being invasive for Vojvodina region (Sorghum halepense, Amaranthus retroflexus, Datura stramonium). The observed low floristic diversity may be related to unbalanced ecological conditions in a newly established crop, invasive species, comparatively low fertilization, allelopathic relations, and possibly robust habitus of the main crop. However, although the flora was low in diversity, both narrow and broadleaf species were represented, with the average infestation as high as 16 individuals per m2. In addition, since the recorded weeds flower from Mart to November, until the development of more efficient methods that are in compliance with the principles of organic agriculture, mechanical weeding should be performed at least three times during the growing season. To our knowledge, this is the first such report on organic common mallow in agro ecological conditions of Serbian province Vojvodina and represents the first step in establishing the adequate weed control measures.

Assessing Selection Parameters for Improving Yield in Organically Grown Onion

Summary An increasing interest in organically grown vegetables has led to an increasing demand to select cultivars meeting the requirements of the production system. This two-year field study was undertaken to assess the effects of organic and conventional nutrient regimes on onion (Allium cepa L.) yield and several yield contributing characters, as well as to identify the traits that could be important when selecting genotypes attended for different production systems. The trial involved five commercially grown onion cultivars and four nutrient regimes: bacterial fertilizer, fully decomposed farmyard manure, without fertilization (organic) and NPK fertilization (conventional). Onion yield, bulb weight, number of bulbs plot−1, number of days from sowing to emergence, vegetation period, plant height, neck diameter, neck length, bulb diameter, bulb height and bulb index have been analyzed. Significant differences concerning all analyzed traits have been found among the cultivars, treatments and years, with significant corresponding interactions. The obtained results imply the specific adaptation to the particular treatments and weather conditions and therefore the possibility to select onion cultivars performing well in organic environments. Path coefficient analysis revealed positive direct effects of bulb weight and number of bulbs plot−1 on yield, as well as negative direct effects of plant height and number of days from sowing to emergence; therefore, those traits should be considered when selecting genotypes attended for different production systems. Other traits affected yield indirectly, mostly positively via bulb weight.

Flora of natural pasture near village Idjos as a indicator of habitat conditions

The natural and semi-natural pastures are highly endangered habitats in Serbia and the world and they are habitats of the unique flora and vegetation. Many of them are on the list of priority habitats for biodiversity conservation. Therefore, the starting point for the assessment, monitoring and conservation of biodiversity of pastures is to study the they flora and vegetation. These ecosystems are very sensitive to environmental conditions and anthropogenic influences, and the understanding of the relationship between plants and environmental factors is essential. The development of plants on a habitat depends of environmental factors, because they are excellent indicators of the habitat conditions. The aim of this paper is to assess the prevalent environmental conditions based on the ecological analysis of flora of natural pasture near village Iđos. This would assist its sustainable use and maintenance of its agricultural productivity, and also helped the recovery of this endangered natural ecosystem. The studied paature flora comprises 137 taxa (129 species, 7 subspecies and 1 variety). Based on the ecological analysis of the identified taxa, near village Iđos, the studied ecosystem - in temperate climate conditions (Kx= 3,18), on a soil characterized by considerable degree of salinity in places (S+ = 35,04%) - is moderately moisture (Fx = 2,80), neutral to mildly acidic (Rx = 3,26), moderately rich in nitrogen and nitrogen compounds (Nx = 3,05), and in organic compounds (Hx = 2,96), moderately aerated (Dx = 4,08), and subject to a favorable light (Lx = 3,80) and thermal regimen (Tx = 3,91).