| photosynthetic acclimation to light in woody and herbaceous species: a comparison of leaf structure, pigment content and chlorophyll fluorescence characteristics measured in the field. | acclimation of foliage photosynthetic properties occurs with varying time kinetics, but structural, chemical and physiological factors controlling the kinetics of acclimation are poorly understood, especially in field environments. we measured chlorophyll fluorescence characteristics, leaf total carotenoid (car), chlorophyll (chl) and nitrogen (n) content and leaf dry mass per area (lma) along vertical light gradients in natural canopies of the herb species, inula salicina and centaurea jacea, a ... | 2012 | 21972867 |
| anatomy of subterranean organs of medicinally used cardueae and related species and its value for discrimination. | numerous species of the asteraceae, the composites, are famous for their use in both traditional and conventional medicine. reliable anatomical descriptions of these plants and of possible adulterations provide a basis for fast identification and cheap purity controls of respective medicinal drugs by means of light microscopy. nevertheless, detailed comparative studies on root and rhizome anatomy of valuable as well as related inconsiderable composite plants are largely missing yet. the presente ... | 2011 | 21617780 |
| earthworm and belowground competition effects on plant productivity in a plant diversity gradient. | diversity is one major factor driving plant productivity in temperate grasslands. although decomposers like earthworms are known to affect plant productivity, interacting effects of plant diversity and earthworms on plant productivity have been neglected in field studies. we investigated in the field the effects of earthworms on plant productivity, their interaction with plant species and functional group richness, and their effects on belowground plant competition. in the framework of the jena ... | 2009 | 19526252 |
| survey of microfungi in the kleinwalsertal (austrian alps). | during an excursion to the alps near the german/austrian border (kleinwalsertal) in august 2007, we were able to collect more than 40 species of microfungi as parasites or saprophytes on different parts of wild plants. some of them have been observed only rarely until now. most of the species collected belong to the classes ascomycotina, basidiomycotina, and deuteromycotina. for example: -leptosphaeria jaceae holm on centaurea jacea l.; -mycosphaerella equiseticola bond.-mont. on equisetum telma ... | 2008 | 19226751 |
| biological monitoring of ozone: the twenty-year italian experience. | tropospheric ozone is a growing environmental menace in italy and in the whole mediterranean basin. the importance of active biomonitoring of this pollutant with hypersensitive bel-w3 tobacco plants is stressed, and several examples of field studies carried out in italy with this technique are presented. current limitations are discussed, with special emphasis on data quality assessment and the opportunity of adopting easy-to-use kits based on tobacco germlings instead of adult plants. a standar ... | 2006 | 16395456 |
| microfungi on compositae in the ruhr basin. | forty-three microfungi have been observed on thirty species of the compositae occurring in several locations in the ruhr basin in north rhine-westphalia. many fungi belong to the ascomycetes (erysiphales, diaporthales, dothideales, leotiales and pleosporales) and to the deuteromycetes (melanconiales, moniliales and sphaeropsidales). other fungi wich were found in our investigation belong to the basidiomycetes (uredinales) and to the oomycetes (peronosporales). some recorded microfungi have been ... | 2002 | 12701426 |
| effects of elevated co2 on flowering phenology and nectar production of nectar plants important for butterflies of calcareous grasslands. | effects of elevated co2 on flowering phenology and nectar production were investigated in trifolium pratense, lotus corniculatus, scabiosa columbaria, centaurea jacea and betonica officinalis, which are all important nectar plants for butterflies. in glasshouse experiments, juvenile plants were exposed to ambient (350 μl l(-1)) and elevated (660 μl l(-1)) co2 concentrations for 60-80 days. elevated co2 significantly enhanced the development of flower buds in c. jacea. b. officinalis flowered ear ... | 1998 | 28307818 |
| patterns of allozyme variation in diploid and tetraploid centaurea jacea at different spatial scales. | the extent and spatial patterns of genetic variation at allozyme markers were investigated within and between diploid and autotetraploid knapweeds (centaurea jacea l. sensu lato, asteraceae) at contrasted geographic scales: (1) among populations sampled from a diploid-tetraploid contact zone in the northeastern part of the belgian ardennes, and (2) within mixed populations from that zone where diploids and tetraploids coexist. our data were also compared with a published dataset by sommer (1990) ... | 2001 | 11430655 |
| pollination, seed set and seed predation on a landscape scale. | we analysed the combined effects of pollination and seed predation on seed set of centaurea jacea in 15 landscapes differing in structural complexity. in the centre of each landscape, a patch of centaurea plants was established for standardized measurements of flower visitation, seed predation and seed set. both the number of flower-visiting bees and the proportion of flower heads damaged by seed predators increased with landscape complexity, which was measured as the proportion of semi-natural ... | 2001 | 11506681 |
| allozyme segregation and inter-cytotype reproductive barriers in the polyploid complex centaurea jacea. | in eastern belgium, diploid and tetraploid knapweeds (centaurea jacea l. s. l.) show a parapatric distribution with a contact zone. to compare the success of inter- and intra-cytotype crosses, and to investigate the pattern of allozyme segregation, controlled crosses involving plants from this contact zone were performed. polysomic inheritance at two loci was observed in tetraploids, suggesting an autopolyploid origin. two crosses allowed the detection of double reduction events in tetraploids a ... | 2001 | 11703503 |
| intra-specific variability of ozone sensitivity in centaurea jacea l., a potential bioindicator for elevated ozone concentrations. | brown knapweed (centaurea jacea l.) has been suggested as a potential bioindicator for tropospheric ozone (o3), but little is known about the intra-specific variation in o3 sensitivity in this wild species. the aim of this study was to quantify the differences in o3 sensitivity among and within five populations, and to relate the differences to morphological, phenological, and genetic characteristics. these parameters were periodically recorded in two consecutive experiments on a total of 357 pl ... | 2004 | 15210270 |
| the interplay between shifts in biomass allocation and costs of reproduction in four grassland perennials under simulated successional change. | when perennial herbs face the risk of being outcompeted in the course of succession, they are hypothesized to either increase their biomass allocation to flowers and seeds or to invest more in vegetative growth. we tested these hypotheses in a 3-year garden experiment with four perennials (hypochaeris radicata, cirsium dissectum, succisa pratensis and centaurea jacea) by growing them in the midst of a tall tussock-forming grass (molinia caerulea) that may successionally replace them in their nat ... | 2006 | 16400509 |
| ozone stress and antioxidant substances in trifolium repens and centaurea jacea leaves. | ozone-sensitive (nc-s clone) and resistant plants (nc-r clone) of trifolium repens and centaurea jacea were exposed to moderate ozone concentrations in ambient air. the aim of this study was the investigation of the relation between ozone-sensitivity and leaf concentrations of antioxidants (ascorbic acid, total phenolics and total antioxidant capacity). nc-r clone showed the highest concentrations of antioxidants with 50-70% more ascorbic acid than nc-s. nc-r had about 5 times more ascorbic acid ... | 2007 | 16753243 |
| characterization and isolation of some genes of the shikimate pathway in sensitive and resistant centaurea jacea plants after ozone exposure. | centaurea jacea has been suggested as a potential bioindicator for ozone, but little is known about its intraspecific variation in sensitivity, especially at molecular level. the effects of ozone (200 ppb, 5 h) on sensitive and resistant lines of centaurea have been investigated at the end of fumigation. sensitive plants showed characteristic symptoms of injury in the form of diffuse discoloration stipples on leaves. a pcr-based approach was used to identify and isolate a partial-length cdna cod ... | 2008 | 17706847 |
| effective long-distance pollen dispersal in centaurea jacea. | agri-environment schemes play an increasingly important role for the conservation of rare plants in intensively managed agricultural landscapes. however, little is known about their effects on gene flow via pollen dispersal between populations of these species. | 2009 | 19707542 |
| cytogenetic studies of three european species of centaurea l. (asteraceae). | cytogenetic analysis of several populations of centaurea jacea (2n = 4x = 44), c. oxylepis (2n = 4x = 44) and c. phrygia (2n = 2x = 22) was performed using flow cytometry, differential chromosome staining and fish. in all species arabidopsis-type telomeric repeats hybridized only to the terminal part of chromosomes. in c. phrygia three pairs and in c. oxylepis six pairs of chromosomes revealed the hybridization signals of 45s rdna. centaurea jacea showed polymorphism in the 45s rdna loci number, ... | 2009 | 19765095 |
| metal concentrations in the soils and native plants surrounding the old flotation tailings pond of the copper mining and smelting complex bor (serbia). | in this study concentrations of metals in the native plants and soils surrounding the old flotation tailings pond of the copper mine were determined. it has been established that the soil is heavily contaminated with copper, iron and arsenic, the mean concentrations being 1585.6, 29,462.5 and 171.7 mg kg(-1) respectively. all the plants, except manganese, accumulated metallic elements in concentrations which were either in the range of critical and phytotoxic values (pb and as) or higher (zn), a ... | 2012 | 22314513 |
| bioactivity-guided isolation of antiproliferative compounds from centaurea jacea l. | bioassay-guided fractionation of the chloroform extract of centaurea jacea l. afforded the isolation of cirsiliol, apigenin, hispidulin, eupatorin, isokaempferide, axillarin, centaureidin, 6-methoxykaempferol 3-methyl ether, trachelogenin, cnicin, 4'-acetylcnicin and three aliphatic glucose diesters, including the new natural product 1β-isobutanoyl-2-angeloyl-glucose. the structures of the compounds were established on the basis of spectroscopic analyses (uv, ms and nmr). all compounds were isol ... | 2012 | 22537643 |
| secondary metabolites from the aerial parts of centaurea pannonica (heuff.) simonk. from serbia and their chemotaxonomic importance. | the non polar extract of centaurea pannonica (heuff.) simonk., growing wild in serbia, was studied and twenty-five compounds including 14 sesquiterpene lactones, 7 flavonoids, 3 lignans and 1 phenylpropanoid glycoside were isolated. all compounds were isolated for the first time from this species. among them, one germacranolide 2α-hydroxy, 8-dehydroxy 15-o-methacrylate salonitenolide (1) and two guaianolides 2α,8α-dihydroxy-dehydrocostus lactone (2) and pannonin (3) are new natural compounds. th ... | 2013 | 23827325 |
| effects of 'target' plant species body size on neighbourhood species richness and composition in old-field vegetation. | competition is generally regarded as an important force in organizing the structure of vegetation, and evidence from several experimental studies of species mixtures suggests that larger mature plant size elicits a competitive advantage. however, these findings are at odds with the fact that large and small plant species generally coexist, and relatively smaller species are more common in virtually all plant communities. here, we use replicates of ten relatively large old-field plant species to ... | 2013 | 24349177 |
| influence of different plant species on methane emissions from soil in a restored swiss wetland. | plants are a major factor influencing methane emissions from wetlands, along with environmental parameters such as water table, temperature, ph, nutrients and soil carbon substrate. we conducted a field experiment to study how different plant species influence methane emissions from a wetland in switzerland. the top 0.5 m of soil at this site had been removed five years earlier, leaving a substrate with very low methanogenic activity. we found a sixfold difference among plant species in their ef ... | 2014 | 24586894 |
| plant density can increase invertebrate postdispersal seed predation in an experimental grassland community. | janzen-connell effects are negative effects on the survival of a plant's progeny at high conspecific densities or close to its conspecifics. although the role of janzen-connell effects on the maintenance of plant diversity was frequently studied, only few studies targeted janzen-connell effects via postdispersal seed predation in temperate grassland systems. we examined effects of conspecific density (abundance of conspecific adult plants) on postdispersal seed predation by invertebrates of thre ... | 2016 | 27231530 |
| the anthelmintic ingredient moxidectin negatively affects seed germination of three temperate grassland species. | in animal farming, anthelmintics are regularly applied to control gastrointestinal nematodes. there is plenty of evidence that also non-target organisms, such as dung beetles, are negatively affected by residues of anthelmintics in faeces of domestic ungulates. by contrast, knowledge about possible effects on wild plants is scarce. to bridge this gap of knowledge, we tested for effects of the common anthelmintic formulation cydectin and its active ingredient moxidectin on seed germination. we co ... | 2016 | 27846249 |
| evaluation of methods to measure differential 15n labeling of soil and root n pools for studies of root exudation. | to study patterns of root exudation, the effectiveness of different techniques for in situ 15n labeling of brassica napus, centaurea jacea and lolium perenne with ammonium nitrate was tested. stem infiltration was found to effectively label plants with thicker stems, whereas, for grass species, cutting and immersing the leaf tips into 15n solution proved to be most effective. a microdiffusion technique to isolate ammonium, combined with conventional cation-exchange chromatography to separate nit ... | 2004 | 15386635 |
| some popular medicinal plants and diseases of the upper palaeolithic in western georgia. | palynological studies of cultural layers of cave sediments have been used in order to better understand traditional practices. the upper palaeolithic in georgia (36,000-11,000 cal. bp) provides a rich source of such material. however, up to day from such sediments the identification of medicinal plants has hardly been achieved. large quantities of pollen most notably from entomophilous taxa in fossil spectra can serve as a tool to identify traditionally important species. as these plants are use ... | 2015 | 25769538 |
| adaptive allocation of resources and life-history trade-offs in aphids relative to plant quality. | the need to allocate a limited amount of energy between different life-history traits is a fundamental assumption in life-history theory. however, it has often turned out to be extremely difficult to measure the competing processes that contribute to costs or benefits for individual organisms. the present investigation begins by analysing how an aphid clonal lineage adapts its reproductive investment to moderate changes in host plant quality (e.g. during the life cycle of its host). using centau ... | 1995 | 28306880 |
| physiological responses of uroleucon jaceae (l.) to seasonal changes in the quality of its host plant centaurea jacea l.: multilevel control of adaptations to the life cycle of the host. | exploiters of short-lived plants have evolved strategies in response to physiological changes that occur during the development of their hosts. the ability to adapt to host quality changes is necessary particularly if the mobility of an animal is poor or risk-constrained. in the plant-aphid system centaurea jaceae-uroleucon jaceae, the responses of the aphid to the seasonal changes in its host plant grown in poor and good quality soil were investigated. coarse- and fine-tuned physiological react ... | 1992 | 28313469 |
| [studies on the glycosides of centaurea jacea l. iv. isolation, structure analysis, and synthesis of 4',5,7-trihydroxy-3'6-dimethoxyflavone-7-mono-beta-d-glucopyranoside (jaccosid), a new flavone glycoside from the root of centaurea jacea l]. | | 1973 | 4698557 |
| [investigations on the glycoside from centaurea jacea l. 3. isolation, structure and synthesis of 4,5,7-trihydroxy-3,6-dimethoxy-flavon-7-mono-beta-d-glucopyranoside, a new flavone glycoside from the roots of centaurea jacea l]. | | 1969 | 5809635 |