首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Abstract

The terrestrial orchid, Orchis pauciflora Ten., growing in poor grassland and garrigue of Central Mediterranean region, is local and rare and has been included in the red lists of several Italian regions. We investigated the diversity of fungal associates in O. pauciflora adult plants collected in two protected areas of Tuscany (Central Italy). Genomic DNA was extracted from mycorrhizal roots of 12 orchid plants and the fungal ITS were amplified and sequenced. Several fungal associates, belonging to different taxa of basidiomycetes (Tulasnellaceae) and ascomycetes such as Leptodontidium, Exophiala and Phialophora species, were recovered. The trophic role of these fungi and their impact on O. pauciflora growth and conservation are discussed.  相似文献   

2.
3.
Abstract

The woodland vegetation of Central Albania is studied and discussed along an altitudinal gradient in the Dajti National Park (DNP). The plant species combinations recorded in 168 plots were classified and subjected to indirect gradient analysis using environmental variables of geology, soil, topography, disturbance and grazing impact. The transect over more than 1300 m reflects the biogeographically intermediate paramediterranean vegetation zonation and the relatively humid Mediterranean “hygric series” at its eastern margins. It reveals the total range of woodland types known to occur in Central Albania, thus stressing the representativity of the area regarding biodiversity and biogeography, and its importance for nature conservation. Along the elevation gradient, we found three plant communities of the mesomediterranean Quercetalia ilicis, five of the supramediterranean Quercetalia pubescentis and five of the montane or oromediterranean Fagetalia sylvaticae.  相似文献   

4.
Abstract

Totally, 26 xerohalophytic species belonging to the associations Cakilo-Xanthietum italici and Echinophoro-Elymetum farcti were registered at the Velika pla?a beach (Montenegro); they were distributed following the spatial succession common in this type of habitat. Three transects of different terrain morphology (positioned perpendicularly to the shoreline) were surveyed to establish if there were any differences in the floristic composition and species distribution due to the configuration discrepancy. Moreover, each transect was divided into zones: The first zone from 0 to 30 m inland, the second zone from 30 m to 60 m inland, and the third zone from 60 m to the end of beach (75–115 m, depending on transect length). The floristic composition was relatively uniform in the different transects. However, the number of individuals per species differed significantly among these transects. An analysis of the qualitative composition of transects/zones showed high differences between zones within transects I and II, whereas species composition of zones within transect III was mostly similar. When analyzing the quantitative composition of species, a positive correlation between the distance from the shoreline and the number of individuals per species in transects I and II was registered for most analyzed species (Spearman correlation, p < 0.001). This indicates that terrain configuration affected the ability of present species to become established and propagate.  相似文献   

5.
In the present study, the chemical composition of the essential oils from aerial parts of Centaurea grinensis Reuter (K) collected at ?uta Lova, near Senj (Croatia), and aerial parts (L1) and flowers (L2) of C. apiculata Ledeb. collected near Rebro village, near Breznik town, Znepole Region (Bulgaria), both belonging to subgenus Lopholoma (Cass.) Dobrocz, was evaluated by GC and GC-MS. The main components of K were 4-vinyl guaiacol (21.5%), hexadecanoic acid (16.2%), acetophenone (12.5%). Caryophyllene oxide (15.8%) together with sphathulenol (14.5%) and humulene epoxide II (9.4%) were recognized as the main constituent of both the aerial part (L1) and flowers (L2) of C. apiculata. Furthermore, a complete review on the composition of the essential oils of all the Centaurea taxa belonging to subgenus Lopholoma studied so far has been inserted and cluster analysis (PCA) was carried out.  相似文献   

6.
Abstract

Five populations belonging to three subspecies of Dianthus rupicola Biv. (D. rupicola subsp. rupicola, D. rupicola subsp. aeolicus, and D. rupicola subsp. lopadusanus) and growing in different geographical areas of Sicily were tested for seed germination at various temperatures. All populations showed high germination rates with an optimum temperature between 15°C and 25°C. Efficient seed germination might contribute significantly to the preservation of these subspecies which are currently exposed to several environmental threats.  相似文献   

7.
Abstract

A two-year study has been conducted in an abandoned Pb/Zn mining site, with the aim of investigating the feasibility of phytoremediation using two native Mediterranean plants (Pistacia lentiscus and Scrophularia bicolor) and of assessing the performance of amendments able to reduce the toxic effects of heavy metals. The amendments used were compost, chemical fertilizer, and zeolites, used singly or in combination. Depending on the amendments applied, the two species showed different mortality rates in the different plots, but all produced an increase in P. lentiscus survival, while S. bicolor survival improved only when amended with zeolite or zeolite + fertilizer. Scrophularia bicolor proved to be a more efficient accumulator than P. lentiscus, especially for Pb uptake. Pistacia lentiscus accumulated metals mostly in the roots. The effect of amendments was to generally reduce the bioavailable metal fraction, especially lead, in the plots amended with compost. Pistacia lentiscus proved to be the most suitable species for phytostabilization and environmental restoration, both for its resistance to metals and high phytomass production. The experiments demonstrate that the use of compost not only encourages this kind of revegetation in degraded areas, but is also an economical option that uses a by-product of solid municipal waste treatment.  相似文献   

8.
Abstract

All four diastereoisomers of 3-thymine-1-(tbutoxycarbonyl)aminocyclopentane- 1-carboxylic acid have been synthesised from (S)-dimethyl malate and thymine monomer 12 has been incorporated into an α-cycloPNA oligomer.  相似文献   

9.
Giant bear-dogs of the genera Amphicyon and Ischyrocyon (Carnivora, Amphicyonidae, Amphicyoninae) were the largest carnivorans in North America during middle and late Miocene (17.5–8.8 Mya) with a dental and skeletal morphology that combined features found in living Ursidae, Canidae, and Felidae. This study tests previously proposed models of diet and hunting behaviour of these extinct carnivorans. Relative grinding area (RGA) of lower molars and wear pattern on upper molars suggest that bear-dogs were carnivorous. Amphicyon and Ischyrocyon possessed skeletal features of both ambush (short distal limb segments) and pursuit (caudally bent olecranon process of ulna) living predators. Therefore, bear-dogs probably pursued their prey (mediportal ungulates) for a longer distance but at a slower speed than do living ambush predators. Upon catching up to its prey a bear-dog probably seized it with powerfully muscled forelimbs and killed it by tearing into its ribcage or neck with canines set in a narrow rostrum.  相似文献   

10.
Abstract

To analyze biomass and nutrient dynamics of Mediterranean seasonal dimorphic shrubs, aboveground biomass (AGB) and belowground biomass (BGB), litterfall (LF), aboveground net annual primary production (ANPP), and nutrient allocation and turnover were estimated in Cistus salviifolius and C. ladanifer, during two years, in southern Portugal. AGB, BGB, LF, and ANPP of C. salviifolius are within the range reported for other seasonal dimorphic plants, while those of C. ladanifer are closer to evergreen sclerophylls. Leaf renewal was higher for C. salviifolius than for C. ladanifer, especially for winter leaves, while root-to-shoot ratio and accumulation of live wood was greater in the latter. The concentrations of N, K, Ca, and Mg were lower in leaves of C. ladanifer than in those of C. salviifolius, suggesting less nutritive requirements for the former. Moreover, leaf nutrient translocation was higher in C. ladanifer than in C. salviifolius. Therefore, C. ladanifer shrubs seem to be more efficient with respect to carbon uptake, even during severe drought, while those of C. salviifolius act as weaker sinks more susceptible to the negative effects of drought. Additionally, C. ladanifer seems to have a competitive advantage in more arid conditions, as a great proportion of its annual nutrient requirement may derive from internal sources.  相似文献   

11.
The forests in the Spa?va Basin are a complex of lowland forests in the region of Slavonia (eastern Croatia). The present state of the forests is strongly influenced by intensive exploitation and hydro-ameliorative activities carried out in the past. The aim of this study was to consider the extent of changes in species composition, and the extent of environmental changes in forest communities of the Spa?va Basin in relation to research conducted between 1969 and 1971. The species composition of four communities (Carpino betuli-Quercetum roboris, Genisto elatae-Quercetum roboris aceretosum tatarici, and caricetosum remotae, and Leucojo-Fraxinetum angustifoliae) is studied by comparing 41 old and 57 new relevés. Changes were estimated using ordinations (RDA, CCA, DCA) and changes in species frequency and cover. A general trend of moisture reduction was noticeable among all communities. All vegetation types are becoming floristically more similar. An increase in frequency and cover of flood intolerant woody species (such as Carpinus betulus, Cornus sanguinea, Tilia tomentosa, and Acer tataricum) as well as a decrease of vernal species related to wet habitats are particularly evident. The succession of all studied communities is resulting in loss of the mosaic community pattern characteristic of lowland alluvial forests.  相似文献   

12.
Total extracts and kuwanon G from Morus nigra root bark showed antifungal activity against several phytopathogenic fungi, with minimal inhibitory concentration (MIC50) ranging from 32 to 128 μg/ml and from 16 to 64 μg/ml, respectively. Acetonic extracts inhibited 60% B. cinerea biofilm formation at concentration of 128 μg/ml.  相似文献   

13.
P. Petrou 《Plant biosystems》2013,147(3):522-533
Abstract

The present study was carried out in abandoned fields in central Cyprus. The main objective was to examine the impact of the regeneration environment on the establishment and survival of Pinus brutia seedlings. Sixty-four permanent plots of 16 m2 were randomly established in two distinct sites. Four regeneration environments were recorded: (a) bare soil under the crown of a P. brutia tree, (b) soil under the canopy of a P. brutia tree and low shrubs, (c) bare soil in open areas, and (d) soil under the canopy of low shrubs in open areas. All P. brutia seedlings were classified in categories according to their regeneration environment. In all plots, the density of the P. brutia seedlings was measured in three different seasons (spring, summer, autumn). Soil temperatures were recorded, samples of surface soil were taken and the percentage of soil organic matter was measured. The main conclusions drawn from this research were the following: (1) the mature P. brutia trees and low shrubs facilitate the establishment and especially the survival of P. brutia seedlings, as all seedlings in bare vegetation ground had died by the end of the growing season, and (2) the importance of facilitation increases as abiotic stress rises.  相似文献   

14.
Constraining the origin of animal groups is allowed, to some extent, by discoveries of Cambrian Lagerstätten that preserve both mineralizing and nonmineralizing organisms. A new species is reported here of the Cambrian arthropod Skania, which bears an exoskeleton that shares homologies with the Neoproterozoic (Ediacaran) organism Parvancorina and firmly establishes a Precambrian root for arthropods. A new monophyletic group, Parvancorinomorpha, is proposed as the first clade within the arthropod crown group demonstrably ranging across the Neoproterozoic–Paleozoic transition. The Parvancorinomorpha is interpreted to be the sister group of the Arachnomorpha. Incipient cephalization in Skania and related genera represents a step in the progression toward division of a cephalon from a large posterior trunk as shown in Cambrian arachnomorphs such as naraoiids and the addition of a pygidium and thoracic tergites as shown in the arachnomorph clade basal to trilobites. This evidence can serve as a new calibration point for estimating the divergence time for the last common ancestor of arthropods and priapulids based on molecular clock methods.  相似文献   

15.
Abstract

A new species of Stipa, endemic to Sicily, named Stipa valdemonensis is described here. The new taxon is related to Stipa crassiculmis. Owing to the small number of individuals observed, in few restricted localities only, it is assigned the IUCN threat status “vulnerable”.  相似文献   

16.
The present work is aimed at studying several Asperula (Rubiaceae) sect. Cynanchicae populations in southern Apennines, Italy, with particular reference to those referred to A. calabra, by employing biometrical methods on macromorphological data. Among other historical misapplications, A. cynanchica subsp. cynanchica seems to be very rare or missing in southern Italy. The enigmatic Asperula calabra, confirmed to be limited to a single mountain population in Calabria, appears to be strictly related to A. aristata subsp. scabra, so we suggest to treat it as a further subspecies of A. aristata. This latter species is otherwise distributed throughout southern Italy with subsp. scabra and subsp. aristata, characterised by slight morphological differences, which are correlated to altitudinal ranges.  相似文献   

17.
Abstract

The production of carotenoids from Blakeslea trispora cells in a synthetic medium has been reported, with the main products being β-carotene, lycopene, and γ-carotene. The effect of biomass pretreatment and solvent extraction on their selective recovery is reported here. Eight solvents of class II and III of the International Conference of Harmonization: ethanol, methanol, acetone, 2-propanol, pentane, hexane, ethyl acetate, and ethyl ether, and HPLC analysis were used for the evaluation of their selectivities towards the three main carotenoids with regard to different biomass pre-treatment. The average Cmax values (maximum concentration of caronoids in a specific solvent) were estimated to 16 mg/L with the five out of eight solvents investigated, whereas methanol, pentane, and hexane gave lower values of 10, 11, and 9 mg/L, respectively. The highest carotenoid yield was obtained in the case of wet biomass, where 44–56% is recovered with one solvent and three extractions and the rest is recovered only after subsequent treatment with acetone; thus, four extractions of 2.5 h are needed. Two extractions of 54 min are enough to recover carotenoids from dehydrated biomass, with the disadvantage of a high degree of degradation. Our results showed that, for maximum carotenoid recovery, ethyl ether, 2-propanol, and ethanol could be successfully used with biomass without prior treatment, whereas fractions enriched in β-carotene or lycopene can be obtained by extraction with the proper solvent, thus avoiding degradation due to time-consuming processes.  相似文献   

18.
Abstract

Synthetic routes towards different 2-α-L-arabinopyranosyl-3-thioxo-2,3-dihydro-1,2,4-triazin-5(4H)-/ones or thiones were investigated. Primary human anticancer screening of two selected compounds resulted in an active compound against SF-268 (CNS) cell line.  相似文献   

19.
Abstract

A phytosociological study of the alliance Carpinion orientalis in the hilly and subcoastal areas of the Italian peninsula is presented. These woods are included in the suballiances Laburno-Ostryenion and Lauro-Quercenion; the distinction between these two suballiances is not always easy also because of the conservation status of these forest ecosystems. The hilly and subcoastal Turkey oak woods of the alliance Carpinion orientalis are mainly distributed on the Adriatic side of the Italian peninsula, where they are found on neutro-basic substrata to which these coenoses are linked. The Turkey oak woods of the alliance Teucrio siculi-Quercion cerridis are strongly linked to the acidic substrata typical of the Tyrrhenian side, but are sporadically found on the Adriatic side within small enclaves with more acidic substrata. A numerical analysis allowed us to rearrange the lower hierarchical levels of the associations of Turkey oak woods of the alliance Carpinion orientalis. In particular, the association Lonicero xylostei-Quercetum cerridis is included in the alliance Carpinion orientalis, and the new subassociation festucetosum exaltatae is proposed. The subassociation rosetosum arvensis is proposed for the association Daphno laureolae-Quercetum cerridis, and the new subassociation cytisophylletosum sessilifolii of the association Aceri obtusati-Quercetum cerridis is described.  相似文献   

20.
Abstract

Temporal variation in allele frequencies in a natural population of wild Vigna unguiculata was studied by making monthly collections of seeds over a two-year period. Using starch gel electrophoresis, four out of seven loci analysed were shown to be polymorphic (Enp, Fdh, Fle3 and Pgd2 ). These four loci showed significant variation in allele frequencies over time. Changes in population structure over time were analysed using F-statistic estimators. Although heterogeneity was evident between loci, the analysis showed significant differentiation among months within a year for all polymorphic loci. Fixation indexes were all positive and statistically different from zero, highlighting a significant departure from random mating. Using analysis of variance (ANOVA), the pattern of inbreeding (f) showed significant changes over time (season); among the polymorphic loci, Enp most strongly contributed to this significance. Significant correlations were found between allele frequencies at different loci. The monthly average gene diversity (He) and allele frequencies at the Enp locus were found to be significantly correlated with weather conditions (temperature and rainfall distribution). These allele frequency deviations over time can be attributed to changes in pollinator behaviour, and frequent genetic bottlenecks that are associated with changes in environmental conditions.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号