Biologia, Bratislava 55 (4), 2000
Double fertilisation presents the more progressive trend in the reproductive system of phylogenetically most advanced gymnosperms. This phenomenon is doubtless closely connected with the origin and powerful evolution of angiosperms. The hybrid character of the endosperm as the nutritional and regulatory tissue for the embryo seems to be not only the advantage for the embryo development but also for the adaptability of the sexual progeny to the environmental changes.
Key words: double fertilisation, endosperm, embryo, isolated embryos, in vitro fertilisation, angiosperms.
The studied reservoir resulted from peat exploitation and its plant cover continually expands. Its specific diatom flora resulted from acid water and considerable isolation. A total of 161 diatom taxa were identified. In the classification of water-pH-related occurrence (Van Dam et al., 1994) they were divided into acidobionts (occurring at pH < 5.5), Eunotia exigua, E. paludosa, Frustulia rhomboides var. crassinervia, Navicula festiva, Pinnularia braunii, Tabellaria quadriseptata, and acidophils (occurring at pH <5.5 and <7.0), Anomoeoneis brachysira, A. styriaca, Cyclotella antiqua, Cymbella gracilis, C. hebridica, Eunotia arculus, E. implicata, E. incisa, E. intermedia, E. minor, E. monodon var. bidens, E. praeupta, E. serra var. tetraedron, Frustulia rhomboides, Navicula hambergii, N. subtilissima, Neidium affine var. longiceps, Pinnularia acoricola, P. appendiculata, P. divergentissima, P. gibba var. linearis, P. nodosa, P. subcapitata, Stauroneis anceps f. gracilis, Tabellaria flocculosa. On the basis of taxa that are dominant, subdominant or characteristic for the reservoir its water may be determined as oligotrophic-dystrophic, scarce in electrolytes, of pH ranging from 5.3 to 6.7.
Key words: diatoms, peat post-excavation pit, pH-dependent occurrence, Poland.
The results of phytoplankton species diversity studies of the Albanian part of Lake Shkodra in 1998-1999 are presented. Lake Shkodra is the largest lake in the Balkan Peninsula situated transboundary between the Yugoslavian Federal Republic (Montenegro) and Albania. It is a large, but shallow lake of an oligotrophic character. In material collected from 9 sampling stations altogether 142 genera with 455 species and infraspecific taxa were determined; majority of them (255) have not been recorded in the Montenegro part of Lake Shkodra by Petkovia (1981). The highest number of species and infraspecific taxa were found in Bacillariophyceae (242) and Chlorophyceae (97), followed by Conjugatophyceae (35), Euglenophyceae (35) and Cyanophyceae (24); other groups were represented only by some taxa. In spite of a relatively rich phototrophic microflora, Lake Shkodra according to the phytoplankton species composition can be classified oligotrophic.
Diatoms dominated in most samples, with Cyclotella ocellata, C. distinguenda, Asterionella formosa, Fragilaria ulna, Aulacoseira ambigua, Cymbella affinis, Gomphonema acuminatum, Navicula capitatoradiata. From other algal groups belonged to the characteristic species of Lake Shkodra phytoplankton: Ceratium hirundinella from Dinophyta, Dinobryon sociale and D. divergens from Chrysophyceae, Merismopedia glauca, Microcystis aeruginosa and Radiocystis aphanothecoidea from Cyanophyta, Pediastrum simplex, P. duplex var. gracillimum, Coelastrum polychordum and Scenedesmus perforatus from Chlorophyceae.
Key words: phytoplankton, species diversity, Lake Shkodra, Albania.
The aquatic macrophyte vegetation of sawgrass (Cladium mariscus Pohl.) was found to be suitable substrate for colonisation of epiphytic diatoms in Plitvice Lakes (Croatia). Taxonomic composition, frequency of appearance, abundance, floral similarity and saprobity index of diatoms on live and dead stalks of Cladium mariscus, were determined. Total number of species 137, have been determined in the epiphytic community. 96 species were found on live, 111 on dead stalks, while 51% of total number were common species. The dominant community was Cymbella-Achnanthes-Gomphonema-Fragilaria-Navicula. High coefficient of floral similarity between live and dead stalks was calculated. The low index of saprobity indirectly indicated low content of dissolved organic matter and stability of the ecosystem.
Key words: epiphytic diatoms, cell size, karstic waters, saprobity, Plitvice Lakes, Croatia.
Effects of autumnal stratification on phytoplankton communities at different depths were studied in Lake Solumsjö, NE Sweden. Species number, Shannon-Weaver’s, Margalef’s and Menhinick’s indices as well as cluster analyses using presence-absence with abundance matrices were applied. All diversity indices used clearly indicated higher diversity in epilimnion compared to that in hypolimnion. This pattern can be explained by sole dominance of Trachelomonas volvocinopsis under predominantly anoxic conditions and high concentrations of iron and manganese below the thermal gradient. Stratification disappeared between September 29 and October 4, thus leading to homogenisation of water column and similar phytoplankton communities at all depths. Cluster analyses using presence-absence with abundance matrices turned out to be a powerful tool when studying temporal changes in phytoplankton communities as a result of stratification patterns. Two distinct clusters at depths of 0, 2 and 10 m were clearly separated: one containing algal communities during stratification and one containing algal communities after the thermal gradient disappeared. At the depth of 5 m more homogeny between phytoplankton communities under stratified and mixed conditions was observed.
Key words: phytoplankton, stratification, diversity indices, multivariate methods, eutrophic lakes, Sweeden.
Genus Solenopsora in Slovakia is discussed. The species S. candicans, not included in checklists or overviews of Carpathian lichen-flora, is reported from Slovakia for the first time. Data on distribution of S. carpatica, having been known in Slovakia only from its locus classicus, were supplemented.
Key words: lichens, Solenopsora, the Carpathians , Slovakia.
In Bratislava, an important industrial centre, air pollution has significantly increased since 1960. A grove, called Panónsky háj, situated 12 km NE from the city centre and on the border of the air pollution field, was chosen to study epiphytes on permanent plots. The investigations started in 1973, a trunk of Quercus robur was examined. A collapsible wire net of 312 quadrates was used, covering 54,750 cm2. Observations were carried out until 1989. Steady deterioration of the epiphytes was registered, with a decrease of number of species at individual quadrates and an increase of number of quadrates with only one species present. Nevertheless, symptoms of certain restoration in the last years were noted, due to the decrease of air pollutants concentration. Parmelia tiliacea disappeared totally, Parmelia glabratula and Evernia prunastri distinctly decreased too. Pertusaria albescens showed no changes in its frequency. That of Parmelia sulcata (represented only by young thalli) slightly increased. The same was true about Pleurococcus vulgaris, whereas the frequency of Hypnum cupressiforme increased significantly. During the period of 16 years the plot was not permanently colonised by any new species.
Key words: epiphytic lichens, mosses, algae, permanent plot, air pollution, monitoring, SW Slovakia.
Oreas martiana (Hoppe et Hornsch.) Brid. was long considered to be a species restricted to the alpine zone of the Alps. In due course it was found in the Himalayas and the Caucasus Mts. Later finds were made in Siberia, Mongolia, China and Japan. Recently it has been found in North America (Colorado), British Columbia, Alaska and Greenland. The species was unknown from the Carpathians and from the north of Europe. In 1999 the species was found by the second author (R. Šoltés) in the Carpathians in the High Tatra Mts.
Considering that the High Tatra Mts. are well explored from bryological point of view, Oreas martiana could be a neophyte, or glacial relic species. Further investigation is needed. With respect to its distribution, Oreas martiana is a genuine arcto - alpine circumpolar species.
Key words: Oreas martiana, bryophytes, taxonomy, distribution, Slovakia.
Karyological data on Erysimum odoratum Ehrh. in Slovakia are given. Two cytotypes, 2n = 14 and 2n = 32 of this species, and the map of their distribution on the West Carpathian and Pannonian territory are presented. The hybrid Erysimum odoratum ´ E. wittmannii (2n = 14) was karyogically analyzed for the first time. The records about 2n = 16 plants of E. odoratum Ehrh. from the Stratenská hornatina Mts. and Muránska planina Plain were not confirmed. Notes on previous records from European literature, compared with our own results are included.
Key words: Brassicaceae, Erysimum, Erysimum odoratum, Erysimum wittmannii, karyology, chromosome numbers, hybridization, Slovakia
This paper presents the results of karyological analysis of four species from the section Alchemilla Rothm., subsection Calycantum Rothm., series Calycinae Bus. Specimens studied karyologically originated from Northeast Anatolia (Turkey). Their chromosome numbers were as follows: A. transcaucasica Rothm. 2n=128-140; A. retinervis Bus. 2n=101-106; A. ellenbergiana Rothm. 2n=120-132; A. dura Bus. 2n=108-126. From cytological point of view Alchemilla presents a diffucult object. All studied species from Northeast Anatolia are proven to be high polploids like species of Alchemilla investigated from various geographic areas.
Key words: chromosome numbers, Alchemilla, Turkey.
In the present paper we show that the concept of the alliance Alyssion euboei (Cisto-Micromerietea), an endemic vegetation unit described from Euvoia island (Greece) by Brullo et al. (1997), is very heterogeneous (comprising a woodland, phrygana, and therophyte-rich communities) and its name should be rejected as nomen dubium. Also the Erico manipuliflorae-Pinetum halepensis (designated as holotype of the alliance) should be rejected as nomen dubium because of problematic selection of the nomenclature type. The other two associations assigned to the Alyssion euboei (Stachyo-Alyssetum euboei and Malcolmio-Alyssetum densistellati) were also invalidly described.
Key words: Cisto-Micromerietea, Greece, Mediterranean pine woods, nomenclature of syntaxa, phrygana, Quercetea ilicis, serpentine vegetation, syntaxonomy, Thero-Brachypodietea.
Scanning electron microscopy was used to examine the seeds surface of the Ornithogalum L. species distributed in Black Sea Region of Turkey. Distinct diferences were found among the micromorphological characters of the seeds of O. oligophyllum E. D. Clarke, O. wiademannii Boiss., O. sigmoideum Freyn & Sint., O. orthophyllum Ten. and O. armeniacum Baker. These variations can be used as a taxonomic criterion at specific level for this genus, but it should be combined with other morphological features.
Key words: Liliaceae, Ornithogalum, seed, micromorphology, SEM, Turkey.
The effect of various concentration of different chromium compounds ( Cr III & Cr.VI) on the growth, biochemical and physiological characteristics as well as chemical composition of Triticum aestivum L. plants during early seedling growth was studied. Root and shoot length, fresh as well as dry weight and chlorophyll concentration decreased while the content of soluble proteins and total phenols increased with increasing concentrations of all chromium compounds. An increase in content of leaf soluble proteins could serve for indication of chromium stress. The relative toxicity of Cr (VI) was higher than those of Cr (III).
Key words: Triticum aestivum, growth, chlorophyll content, proteins, chromium toxicity, Cr (III), Cr (VI).
The effect of two gelling agents, agar and Phytagel, on in vitro growth and shoot development of miniature rose and gladiolus was studied. Three parameters were tested: shoot multiplication (number of shoots), the length of the main shoot (gladiolus) or the number of leaves per shoot (rose), and the fresh weight. Significantly higher biomass production (fresh weight) was observed on Phytagel media in both species. Shoot multiplication was significantly higher on Phytagel in miniature rose culture (2.2 times higher compared with agar), but multiplication of gladiolus was more satisfactory on agar (1.26 times higher compared with Phytagel). The number of leaves per shoot of miniature rose was significantly higher on agar medium, and the length of the main shoot of gladiolus was higher on Phytagel compared with agar medium.
Key words: agar, gladiolus, micropropagation, miniature rose, Phytagel.
The green flagellate Euglena gracilis was treated for seven days with concentrations of copper ranging from 0.02 mg L-1 to 2.0 mg L-1. No inhibiting effects were detected in any physiological parameters measured. In general, it seems that enhanced copper concentrations stimulated photosynthetic efficiency (PE) of E. gracilis. Concentrations of copper reported to be critical for the other algae studied (from 0.10 mg L-1 to 0.14 mg L-1) did not show any severe negative effects on E. gracilis. An unusual trend was observed where an increase in PE was followed by an increase in light irradiance necessary to achieve light compensation point. High capacity of E. gracilis to adapt to copper stress is being discussed as a possible explanation for the trends detected.
Key words: Euglena gracilis, bioassay, copper, photosynthesis, water pollution.
The mechanism by which aluminium influences the ion uptake is still poorly understood. In this study the effects of Al on nitrate uptake, nitrate reductase and P-ATPase activity were measured in maize roots exposed to Al for different time period. In short-time experiments (Al-treatment lasting for 1 h) root growth, nitrate uptake as well as nitrate reductase activity have not been influenced by Al. Long-term experiments (Al-treatment lasting for 24 h) significantly reduced the root growth, nitrate uptake, and P-ATPase activity. At the same condition the nitrate reductase activity was slightly inhibited in apical parts of roots while stimulation was observed in root parts more distant from the root apex. The differences found out in our experiments support the prevalent view that Al may influence the ion flux by different mechanisms the extent of which is time dependent.
Key words: aluminium, maize roots, nitrate uptake, nitrate assimilation, P-ATPase activity.
The effect of hydrogen peroxide on the growth of barley, maize, haricot, melon, vegetable marrow, garden radish, and carrot was studied. It was found out that a short-time soaking of seeds in 6x10-2 - 6x10-5 M H2O2 solution enhances their germination, promotes early appearance of sprouts, and accelerates the development of plants. It was noted that swelling test seeds consume less water than control seeds. The data are consistent with the hypothesis that seeds exit from the dormancy as a result of the oxidation reaction catalyzed by NADPH oxidase.
Key words: hydrogen peroxide, plant growth, seed germination.
The naphthoquinone 7-methyljuglone, flavonols quercetin and kaempferol are the main secondary metabolites of Drosera anglica and D. rotundifolia. The content of 7-methyljuglone was evaluated in four leaf ontogenetic phases, in stem and flower of both species studied. The highest content (1.0 to 2.7 % in dry matter) was found in young and in mature green leaves. High content of quercetin was estimated in all aboveground organs of both species (3.4 to 5.7 %). In comparison with other plant organs the highest amount of kaempferol accumulates in the flower (0.41% and 0.58 % respectively).
Key words: Drosera anglica, Drosera rotundifolia, flavonols, kaempferol, 7-methyljuglone, naphthoquinone, quercetin.