Ljiljana Nikolić

Primary production dynamics of dominant hydrophytes in Lake Provala (Serbia)

The objective of this investigation was to analyze the primary production of the dominant hydrophytes by monitoring levels of organic matter and organic carbon and estimating photosynthetic potential via the total chlorophyll content. The survey was conducted in Lake Provala (Serbia) throughout the peak vegetation period of the year 2000. The contents of organic matter and organic carbon for Myriophyllum spicatum L. were 105.11 g m−2 and 73.66 g m−2, Nymphoides peltata (Gmel.) Kunt. were 95.51 g m−2 and 45.26 g m−2 and Ceratophyllum demersum L. were 52.17 g m−2 and 29.75 g m−2. Chlorophyll A (Chl a) and chlorophyll A+B (Chl a+b) pigments ranged from 1.54 mg g−1(Chl a) and 2.1 mg g−1(Chl a+b) in M. spicatum to 5.27 mg g−1(Chl a) and 7.53 mg g−1(Chl a+b) in C. demersum. At full leaf out, the latter aquatic plants exceeded 50% cover of the open water surface. All species achieved maximum growth in June, but significant differences in growth dynamics were observed. At the end of the vegetation period, these plants sink to the bottom and decompose

Nymphoides peltata (Gmel.) Kuntze, Myriophyllum spicatum L. and Ceratophyllum demersum L. biomass dynamics in Lake Provala (the Vojvodina Province, Serbia)

Sixty-five plant species have been found in Lake Provala (the Vojvodina Province, Serbia) and its riparian zone. Among them, three hydrophytes were dominant: Nymphoides peltata, Myriophyllum spicatum and Ceratophyllum demersum. As interactions between different ecological factors, especially light, temperature and nutrient level, are of prime importance for productivity of macrophytes, we analyzed the main physical and chemical indicators of water quality in the studied location. In the vegetation period of the year 2000, the dominant hydrophytes were analyzed for biomass production dynamics in the studied aquatic ecosystem, including fresh weight (FW), dry weight (DW) and ash free dry weight (AFDW). The studied plant species achieved maximum biomass production in June, with statistical differences among the species at the significance level of α = 0.05.

Relationship between plant life forms and ecological indices in a lacustrine ecosystem

This study is the first to analyze the relationship between ecological indices (substrate moisture, nutrient content, substrate dispersion/aeration, substrate pH and humus content) and life forms of the vascular flora in and around Lake Provala; these relationships may serve as reliable indicators of the ecological conditions prevailing in this ecosystem. Since the development of certain life forms, in addition to climatic conditions, depends on plant requirements for several major environmental factors expressed as ecological indices, we established the relationship between the ecological index and life form of vascular plants collected over an eight year period in this system using correspondence analysis. We found a significant correlation between the development of certain life forms and levels of substrate moisture, nutrient content and substrate dispersion/aeration. These relationships help explain the predominance of hemicryptophytes and hydro-helophytes in the riparian zone of the lake, as these forms are perfectly adapted to water-saturated or aquatic environments rich in nutrients and relatively well aerated. There was no significant relationship between life forms and substrate pH or the content of organo-mineral compounds (humus) in the soil.

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.

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.

Floristic composition and weed biomass in organic alfalfa crop

The paper presents the results of floristic composition and weed biomass in organic alfalfa crop in different years of alfalfa growing. The experiment was conducted in experimental plots in Futog, during the vegetation period of 2015. The presence of 60 weed species was noted, 49 of all weeds were noticed in the third, 48 in the fourth and 34 in the fifth year of organic alfalfa growing. Quantitative and qualitative structure of weed community depended on the age of alfalfa crop. By the analysis of cover values and the degree of the presence of weed species, it can be seen that species: Rumex obtusifolius L., Taraxacum officinale Web., Cynodon dactylon Pers. and Artemisia vulgaris L. had the greatest significance on weed infestation of alfalfa. The largest number of weed species belonged to the families Poaceae and Asteraceae. The biological spectrum of weeds species was defined by the terophyta dominance, whose number was reduced due to the age of the crop, while the share of hemicryptophytes and geophytes was more or less constant. Although we found a considerable level of infestation of alfalfa, alfalfa biomass reached acceptable values that were significantly higher than the weed biomass, which was statistically highly significant.

ANTIOXIDANT SYSTEMS IN SOME RARE AND ENDANGERED PLANT SPECIES FROM THE PANNONIAN SALINE MEADOWS AND GRASSLANDS

In order to establish the level of oxidative stress, antioxidant status was evaluated in several rare and endangered plant species from southern parts of the Pannonian plain, in Vojvodina province. The quantities of reactive oxygen species and malonyldialdehyde, activities of several antioxidant enzymes and content of reduced glutathione were determined. Also, the DPPH-radical scavenging activity of plant extracts was measured. Several different systems were found to be involved in plant defence against oxidative stress. It seems that antioxidant status could serve as a suitable biochemical criterion for evaluation of the level of stress in plants.