The effects of ambient levels of ozone and summer drought were assessed on a poplar clone (Populus maximowiczii Henry X P. × berolinensis Dippel - Oxford clone) in an open top chamber experiment carried out at the Curno facilities (Northern Italy). Chlorophyll (Chl) a fluorescence parameters (from both modulated and direct fluorescence) were assessed at different hours of the day (predawn, morning, midday, afternoon, and evening), from June to August 2008. This paper compares the results from predawn (PD, before sunrise) and afternoon (AN, in full sunlight) measurements, in order to evaluate the role of high sunlight as a factor influencing responses to ozone stress. Sunlight affected the maximum quantum yield of primary photochemistry (decrease of Fv/Fm) thus indicating photoinhibition. The effective quantum yield (ΦPSII) and the photochemical quenching (qP) were enhanced in the afternoon with respect to the predawn, whereas the nonphotochemical quenching (NPQ) was reduced. The effect of ozone was detected with fluorescence on well watered plants in the first week of July, before the onset of visible symptoms. As far as Fv/Fm are concerned, the differences between ozone-treated and control plants were statistically significant in the predawn, but not in the afternoon. Ozone exerted only minor effects on drought exposed plants because of the reduced stomatal ozone uptake, but effects on the IP phase of the fluorescence transient were observed also in drought-stressed plants., R. Desotgiu ... [et al.]., and Obsahuje bibliografii
Hvězdoše patří k nejběžnějším a přitom nejvíce přehlíženým vodním rostlinám naší květeny. Jsou charakterizovány na jedné straně celkovou redukcí tělní stavby, na druhé straně vysokou měrou fenotypové plasticity – schopností pružně reagovat na změny prostředí změnou habitu. Kvůli těmto vlastnostem patří hvězdoše mezi determinačně obtížné skupiny. Překvapivě však existuje u hvězdošů pozoruhodné množství různých opylovacích způsobů: dokáží se opylovat na vzduchu, po vodní hladině i pod vodou. Kombinace všech těchto tří způsobů opylení není známa u žádných jiných rostlin. Všechny opylovací systémy se pak u hvězdošů kombinují s ojedinělými a kuriózními způsoby samoopylení., Water-starworts (Callitriche) are some of the most common and yet largely overlooked aquatic plants in European flora. They are characterized by overall reduction of the plant body and also exhibit an extraordinary phenotypic plasticity in response to environmental changes, which makes the starwort species very difficult to determine. It is the only genus known to possess all three types of pollination: by air, on the water surface and under water, in addition to some unique self-fertilization mechanisms., and Jan Prančl.
In the CR located on the bio-geographical crossroads of Central Europe, several vegetation types reach their distribution limit here, whereas only three vegetation types and complexes unique or significantly concentrated here are identified: grasslands in the White Carpathian Mts. (the world’s highest number of vascular plant species per certain areas smaller than 50 m2); sandstone pseudokarst landscapes (sharply contrasting vegetation at very short distances); fishponds (specific vegetation especially on their exposed bottoms when drained). and Milan Chytrý, Handrij Härtel, Kateřina Šumberová.
Botanická zahrada v Rio de Janeiru je zajímavým východiskem k pozorování bromeliovitých rostlin. Nachází se v oblasti obzvláště bohaté na zástupce čeledi Bromeliaceae. Zvláštní kapitola je věnována robustním druhům rodu Alcantarea a jejich ekologii. Je zmíněn slavný zahradní architekt Roberto Burle Marx, který uvedl druh Alcantarea imperialis do svých věhlasných zahradních aranžmá., The Botanical Garden of Rio de Janeiro is an interesting starting point for observation of bromeliads. It is located in an area particularly rich in species of the family Bromeliaceae. An emphasis is given to robust species of the genus Alcantarea and their ecology. Roberto Burle Marx, a famous garden and park designer, is mentioned because he introduced the species A. imperialis in his well-known garden arrangements., and Miloslav Studnička.
The flora of the CR harbours 48 endemic (sub)species of vascular plants (plus 26 taxa considered as near-endemic). Most of them occur above the timberline in the High Sudetes Mts. while others are restricted to lowland habitats with specific edaphic or topographic features (serpentine outcrops, calcareous fens, rocks in steep river valleys). Apomicts clearly prevail (49 taxa, especially Hieracium and Sorbus). All endemics are evolutionarily young (neoendemics) and their origin is mostly associated with the Quaternary climatic oscillations. and Jan Suda, Zdeněk Kaplan.
Vedle přímého parazitismu na okolních rostlinách představuje mykoheterotrofie, tedy závislost rostliny na uhlíku získaném od mykorhizních hub, další strategii umožňující přežít bez chlorofylu a vlastní fotosyntézy. Díky sekvenování DNA mykorhizních hub a analýze stabilních izotopů se zjišťuje, že mykoheterotrofní rostliny se často velmi specificky pojí s mykorhizními houbami okolních stromů a že tato strategie je běžnější, než se čekalo. Tento způsob výživy byl totiž nalezen nejen u mnoha nepříbuzných druhů nezelených rostlin, ale i u některých zelených lesních orchidejí a hruštiček, které kombinují mykoheterotrofii s fotosyntézou. Výzkum by se měl více zaměřit na tropické oblasti, kde je nalézáno mnoho odlišností od dobře prozkoumaných druhů mírného pásu., Beside direct parasitism on other plants, plant mycoheterotrophy, i.e. dependence on carbon received from mycorrhizal fungi, is another strategy enabling plants to live without chlorophyll and to perform their own photosynthesis. With the recent use of fungal DNA sequencing and stable isotope analyses it appears that mycoheterotrophic plants mostly highly specifically associate with fungi mycorrhizal on trees, and that the strategy is more widespread than previously expected. It was found not only among many unrelated non-green species, but also among some green forest orchids and pyroloids, which combine mycoheterotrophy with photosynthesis. More research is needed in tropical areas, where the rules observed in temperate regions do not seem to apply., and Marc-André Selosse, Mélanie Roy, Tamara Těšitelová.
Lichens are characterized by the production of a large amount of secondary metabolites. Most of them are specific to these organisms. Lichenologists commonly use the metabolites to distinguish between phenotypically similar taxa. To achieve this aim, they use a plethora of detection methods, including spot reactions, chromatography, and microcrystalization tests. and Jiří Malíček.