| comparison between antifungal and antibacterial activities of several strains of epicoccum purpurascens from the mediterranean area. | the antimicrobial activities of seven epicoccum purpurascens strains isolated either from evergreen oak leaves (quercus ilex) collected over a period of one year, or from the atmosphere were compared in vitro. two strains sporulated and conspicuously inhibited the growth of staphylococcus aureus and trichophyton mentagrophytes. thin-layer chromatographic studies showed the existence of some compounds, such as flavipin, which were common to all the strains. epicorazine b was present in the extrac ... | 1991 | 1784310 |
| honeydew of aphids as a source of sugar for phlebotomus ariasi. | wild-caught phlebotomus ariasi tonnoir, starved until their sugar meals had been digested, were caged for 24 h with plants or plants infested with aphids and then tested for fructose, a constituent of plant sap. no evidence was found that the flies took sap directly from nine types of plants present in their habitat. about two-thirds of flies caged with oak (quercus ilex l.) infested with an aphid [lachnus roboris (l.)] and about a fifth kept with leaves of the french bean (phaseolus vulgaris l. ... | 1987 | 2979545 |
| honeydew sugars in wild-caught phlebotomus ariasi detected by high performance liquid chromatography (hplc) and gas chromatography (gc). | phlebotomus ariasi tonnoir sandflies were caught in light traps hung in oak trees and in a house in the cévennes focus of leishmaniasis in the south of france. the flies were cryopreserved either immediately on removal from the traps, or after starvation for 6-7 days, or after 6-7 days starvation followed by exposure to oak infested with the aphid genera lachnus or thelaxes. after transportation to the laboratory, the sandflies were thawed and aqueous extracts of the crushed flies were analysed ... | 1987 | 2979559 |
| assessment of sensitization to holm oak (quercus ilex) pollen in the mérida area (spain). | sensitization to quercus ilex (holm oak) was studied in 760 patients with clinically suspected sensitization to aeroallergens. prick tests with commercial extracts of q. ilex proved positive in 27 patients; none were monosensitive. nasal and conjunctival provocation tests and specific ige (rast) performed with q. ilex extracts in these patients were negative in all but one patient, who exhibited specific ige titer (by rast) of 7 pru/ml (class 3). we conclude that q. ilex pollen, though obtained ... | 1995 | 7573837 |
| trace metal biomonitoring in the soil and the leaves of quercus ilex in the urban area of naples. | the concentrations of pb, cu, fe, and mn were analyzed in surface deposit and tissue of quercus ilex leaves from several sites of the urban area of naples, exposed to different degrees of air pollution. these included some major roads with heavy traffic loads, squares, and three urban parks. the soil from the trunk base area of q. ilex trees in the same sites was also analyzed for total and available metal contents. pb, cu, and fe contents in the surface deposit and leaf tissue were significantl ... | 1996 | 8834387 |
| visualization of the cytoskeleton within the secondary vascular system of hardwood species. | a single fixation technique has been devised to demonstrate localization of alpha-tubulin (for microtubules) and f-actin (for microfilaments) within the secondary vascular system of hardwood trees by indirect immunofluorescence microscopy using butyl-methylmethacrylate-embedded material. application of this technique to problems of cytomorphogenesis during secondary growth and its versatility are demonstrated with the hardwood species aesculus hippocastanum l., salix viminalis l., s. burjatica n ... | 1997 | 9316269 |
| assessing trace metals in leaves of quercus ilex l. by energy dispersive x-ray spectrometry. | | 1997 | 9442471 |
| anaphylactic reaction to ingestion of quercus ilex acorn nut. | a patient experienced an anaphylactic reaction after eating acorn nuts, fruit of the holm oak (quercus ilex), one of the most abundant trees in spain. several urticaria episodes upon ingestion of peanuts were also referred. | 1998 | 9677139 |
| effects of quercus ilex l. and punica granatum l. polyphenols against ethanol-induced gastric damage in rats. | | 1999 | 9987803 |
| effects of aqueous extracts from quercus ilex l. root bark, punica granatum l. fruit peel and artemisia herba-alba asso leaves on ethanol-induced gastric damage in rats. | the gastroprotective effect of tannic acid and the aqueous extract of quercus ilex l. root bark, punica granatum l. fruit peel and artemisia herba-alba asso leaves was investigated in the rat against ethanol-induced damage. tannic acid, q. ilex and p. granatum extracts gave 100% precipitation of ovine haemoglobin in vitro, whereas a. herba-alba extract was devoid of any protein-binding property. oral administration of these plant extracts or tannic acid induced a significant decrease in gastric ... | 1999 | 10189949 |
| seasonal patterns of terpene content and emission from seven mediterranean woody species in field conditions. | the seasonal pattern of terpene content and emission by seven mediterranean woody species was studied under field conditions. emission rates were normalized at 30 degrees c and 1000 µmol.m.s pfd (photosynthetic photon flux density). bupleurum fruticosum, pinus halepensis, and cistus albidus stored large amounts of terpenes (0.01-1.77% [dry matter]) with maximum values in autumn and minimum values in spring. they emitted large amounts of terpenes (2-40 µg.g dm.h), but with no clear seasonal trend ... | 2000 | 10636836 |
| biochemical and molecular characterization of a laccase from marasmius quercophilus. | the basidiomycete marasmius quercophilus is commonly found during autumn on the decaying litter of the evergreen oak (quercus ilex l.), a plant characteristic of mediterranean forest. this white-rot fungus colonizes the leaf surface with rhizomorphs, causing a total bleaching of the leaf. in synthetic liquid media, this white-rot fungus has strong laccase activity. from a three-step chromatographic procedure, we purified a major isoform to homogeneity. the gene encodes a monomeric glycoprotein o ... | 2000 | 10698753 |
| monoterpene synthase activities in leaves of picea abies (l.) karst. and quercus ilex l. | in addition to direct ecological functions in the interaction of plants with the environment, the emission of monoterpenes, especially from the foliage of evergreen trees, is of great importance for the production of ozone and photochemical oxidants in the troposphere. in the present work, we established a reproducible non-radioactive standard enzyme assay and characterized monoterpene synthase activities in needles of norway spruce (picea abies (l.) karst.) and in leaves of holm oak (quercus il ... | 2000 | 10870179 |
| effect of polyethylene glycol on in vitro degradability of nitrogen and microbial protein synthesis from tannin-rich browse and herbaceous legumes. | determination of microbial degradability of n is important in formulating a sound supplementation strategy for efficient utilisation of basal as well as supplementary diet components. in vitro degradability of n (ivdn) from tannin-containing browses (acacia cyanophylla, acacia albida, acioa barteri and quercus ilex) and two herbaceous legumes (desmodium intortum and desmodium uncinatum) was determined using the in vitro gas-production method coupled with nh3-n measurement in the presence and abs ... | 2000 | 10961163 |
| ericoid mycorrhizal fungi are common root associates of a mediterranean ectomycorrhizal plant (quercus ilex). | mycorrhiza samples of neighbouring quercus ilex and erica arborea plants collected in a postcutting habitat were processed to see whether plants differing in mycorrhizal status harbour the same root endophytes. three experiments were performed in parallel: (i) isolation, identification and molecular characterization of fungi from surface-sterilized roots of both plant species; (ii) re-inoculation of fungal isolates on axenic e. arborea and q. ilex seedlings; (iii) direct inoculation of field-col ... | 2000 | 11050558 |
| model for the study of the impact of atmospheric heavy metals on soil microbial biomass. | in the castelporziano (rome) protected area the inputs of atmospheric heavy metals on the soil-plant system were evaluated by the analysis of stem-flowing water from quercus ilex l. the heavy metals detected in the soil under the canopies exhibited higher concentrations near to the tree trunks, highlighting the tree's capacity to concentrate such polluting substances. microbial biomass, its specific respiration and the biomass calculated as a percentage of total soil organic matter, were utilise ... | 2000 | 11218259 |
| internal remobilization of carbohydrates, lipids, nitrogen and phosphorus in the mediterranean evergreen oak quercus ilex. | remobilization of internal resources is an important mechanism enabling plants to be partly independent of external nutrient availability. we assessed resource remobilization during the growing period in woody and foliar tissues of leafy branches of mature evergreen mediterranean oak (quercus ilex l.) at three field sites. we compared nonstructural carbohydrates, lipids, nitrogen and phosphorus pools in leaves and stems before bud burst (march) and at the end of the growing period (july). we als ... | 2001 | 11260819 |
| water stress responses of seedlings of four mediterranean oak species. | effects of water stress on phenology, growth, stomatal activity and water status were assessed from april to november 1996 in 2-year-old seedlings of quercus frainetto ten. (quercus conferta kit.), quercus pubescens willd., quercus macrolepis kotschy (quercus aegilops auct.) and quercus ilex l. growing in containers in northern greece. all four species developed more than 50% of their total leaf area before the beginning of june--an adaptation to arid climates. well-irrigated plants tended to de ... | 2000 | 11269958 |
| within-tree variation in transpiration in isolated evergreen oak trees: evidence in support of the pipe model theory. | within-tree variation in sap flow density (sfd) was measured in two isolated evergreen oak (quercus ilex l.) trees growing in an oak savannah (dehesa) in southwest spain. sap flow was estimated by the constant heating method. three sensors were installed in the trunk of each tree in three orientations: northeast (ne), northwest (nw) and south (s). sap flow density was monitored continuously from may 18 to september 27, 1993. daily values of sfd ranged between 500 and 4500 mm3 mm-2 day-1. there w ... | 2001 | 11282581 |
| frequent cytoplasmic exchanges between oak species that are not closely related: quercus suber and q. ilex in morocco. | chloroplast (cp) and mitochondrial (mt) dna variation were studied in 97 populations of cork oak (quercus suber) in morocco; in 31 of these populations, holm oak (quercus ilex), a clearly distinct species, also occurred and was compared with q. suber. three cpdna and one mtdna primer pairs were used in the survey, each in combination with one restriction enzyme. six haplotypes belonging to two very divergent lineages were detected; one lineage predominates in each species, and is probably ancest ... | 2001 | 11555243 |
| different sources of reduced carbon contribute to form three classes of terpenoid emitted by quercus ilex l. leaves. | quercus ilex l. leaves emit terpenes but do not have specialized structures for terpene storage. we exploited this unique feature to investigate terpene biosynthesis in intact leaves of q. ilex. light induction allowed us to distinguish three classes of terpenes: (i) a rapidly induced class including alpha-pinene; (ii) a more slowly induced class, including cis-beta-ocimene; and (iii) the most slowly induced class, including 3-methyl-3-buten-1-ol. using 13c, we found that alpha-pinene and cis-be ... | 1996 | 11607702 |
| isolation and functional analysis of a cdna encoding a myrcene synthase from holm oak (quercus ilex l.). | an 859-bp cdna segment of a terpene synthase gene was amplified by pcr from the evergreen sclerophyllous holm oak (quercus ilex l.) using heterologous primers for conserved regions of terpene synthase genes (tps) in dicotyledonous plants. based on the sequence of this segment, homologous primers were designed for amplification by race-pcr of a cdna segment carrying the monoterpene synthase gene myrs. the gene encodes a protein of 597 amino acids including an n-terminal putative plastid transit p ... | 2001 | 11683887 |
| vertical distribution of fine root density, length density, area index and mean diameter in a quercus ilex forest. | we used minirhizotrons to determine the vertical distribution of fine roots in a holm oak (quercus ilex l.) forest in a typical mediterranean area over a 3-year period (june 1994-march 1997). we measured fine root density (number of roots per unit area), fine root length density (length of roots per unit area), fine root area index (area of roots per unit area) and fine root mean diameter. variables were pooled for each 10-cm depth interval to a depth of 60 cm. fine roots tended to decrease with ... | 2001 | 11359714 |
| seasonal pattern of monoterpene synthase activities in leaves of the evergreen tree quercus ilex. | monoterpene synthase activities were measured in current year and 1-year-old leaves of holm oak (quercus ilex l.). the monoterpene synthase activities of the leaves strongly changed with leaf development and leaf age. enzyme activities increased rapidly in spring after leaf emergence, reaching maximum values in summer, which declined during the following winter period. in the next spring monoterpene synthase activities recovered in the old leaves to about one-third of values in the previous year ... | 2002 | 12060257 |
| photosynthetic responses to water deficit in six mediterranean sclerophyll species: possible factors explaining the declining distribution of rhamnus ludovici-salvatoris, an endemic balearic species. | we sought to explain the declining distribution in the balearic islands of the endemic shrub rhamnus ludovici-salvatoris r. chodat, by comparing its photosynthetic response to drought with that of several widely distributed, competing mediterranean species (r. alaternus l., quercus ilex l., pistacia lentiscus l., q. humilis mill. and p. terebinthus l.). all of the study species, except for the two rhamnus species, avoided desiccation by rapidly adjusting their stomatal conductance at the onset o ... | 2002 | 12091150 |
| influence of environmental factors and air composition on the emission of [alpha]-pinene from quercus ilex leaves. | we studied the emission of [alpha]-pinene from quercus ilex leaves. only the abaxial side of the hypostomatous q. ilex leaf emits [alpha]-pinene. light induced photosynthesis and [alpha]-pinene emission. however, the response of photosynthesis to dark-to-light transitions was faster than that of [alpha]-pinene, suggesting that atp controls the emission. the emission was higher at 30 than at 20[deg]c, whereas photosynthesis did not change. therefore, the relationship between photosynthesis and [a ... | 1996 | 12226182 |
| evidence of the photosynthetic origin of monoterpenes emitted by quercus ilex l. leaves by 13c labeling. | the carbon of the four main monoterpenes emitted by quercus ilex l. leaves was completely labeled with 13c after a 20-min feeding with 99% 13co2. this labeling time course is comparable with the labeling time course of isoprene, the terpenoid emitted by other quercus species and synthesized in leaf chloroplasts. it is also comparable with that of phosphoglyceric acid. our experiment therefore provides evidence that monoterpenes emitted by q. ilex are formed from photosynthesis intermediates and ... | 1996 | 12226263 |
| effect of elevated co2 on monoterpene emission of young quercus ilex trees and its relation to structural and ecophysiological parameters. | we investigated growth, leaf monoterpene emission, gas exchange, leaf structure and leaf chemical composition of 1-year-old quercus ilex l. seedlings grown in ambient (350 microl l(-1)) and elevated (700 microl l(-1)) co2 concentrations ([co2]). monoterpene emission and gas exchange were determined at constant temperature and irradiance (25 degrees c and 1000 micromol m(-2) s(-1) of photosynthetically active radiation) at an assay [co2] of 350 or 700 microl l(-1). measurements were made on intac ... | 2001 | 11340044 |
| spatial distribution of photosynthetic response to long-term influence of elevated co(2) in a mediterranean macchia mini-ecosystem. | during an open-top chamber experiment performed in evergreen 'macchia' ecosystem, which was represented by the clumps of natural vegetation dominated by quercus ilex trees, the trees were exposed to one of two co(2) concentrations (ambient co(2), ac-variant and elevated co(2), i.e. ambient plus 350 &mgr;mol co(2) mol(-1), ec-variant) continuously over 5 years. clumps of natural vegetation were enclosed in open top chambers (otcs). within the crowns of investigated quercus ilex trees in otcs, two ... | 2001 | 11337069 |
| foliar antioxidant status of adult mediterranean oak species (quercus ilex l. and q. pubescens willd.) exposed to permanent co2-enrichment and to seasonal water stress. | foliar antioxidants were measured in adult individuals of holm oak (quercus ilex l.) and white oak (q. pubescens willd.) growing in the field either within the vicinity of natural co2 springs or at a nearby control site under ambient co2, which had been previously exposed to either daily irrigation or no irrigation. in oak trees permanently exposed to elevated co2 the activities of antioxidant enzymes tended to be lower and the ascorbate pool was larger and more in reduced form, suggesting an at ... | 2001 | 11789922 |
| fine roots dynamics in a mediterranean forest: effects of drought and stem density. | summer drought is a characteristic trait of mediterranean climates and can limit primary production. the holm oak (quercus ilex l.) forest at the prades experimental complex of catchments (pecc, ne spain) was managed by clearcutting until the 1950s. as a result of this practice, the forest has a high density (13000 stems ha(-1)) that is causing growth stagnation and intense competition for water. a thinning experiment was conducted to release resources, reduce stem competition and improve forest ... | 1998 | 12651348 |
| photosynthesis and photoprotection in quercus ilex resprouts after fire. | plants that resprout after fires often have higher rates of photosynthesis than before a fire. to elucidate the mechanism of this response, we studied gas exchange and chlorophyll fluorescence in quercus ilex l. plants growing on control (unburned) sites and on sites that had been burned the preceding summer. in early july, photosynthetic rates and stomatal conductance were similar in plants on unburned and burned plots, and in young and old foliage within unburned plots. at this time, photochem ... | 1998 | 12651349 |
| seasonal embolism and xylem vulnerability in deciduous and evergreen mediterranean trees influenced by proximity to a carbon dioxide spring. | we investigated how proximity to natural co(2) springs affected the seasonal patterns of xylem embolism in quercus ilex l., quercus pubescens willd., fraxinus ornus l., populus tremula l. and arbutus unedo l., which differ in leaf phenology and wood anatomy. xylem embolism was evaluated in both artificially dehydrated branches and in hydrated apical branches collected at monthly intervals during a 20-month sampling period. initial specific hydraulic conductivity was also evaluated. we found spec ... | 1999 | 12651570 |
| influence of increased atmospheric co(2) concentration on quality of plant material and litter decomposition. | nitrogen (n) and lignin concentrations in plant tissues and litter of plants grown in greenhouses or open-top chambers in elevated atmospheric co(2) concentration were compared with those of plants grown in ambient air in short-term studies. we also compared the n concentration of plant material of quercus ilex l. and q. pubescens willd. growing in the vicinity of natural co(2)-springs with that of the same species growing at a control site. in the short-term studies, elevated co(2) caused signi ... | 1999 | 12651573 |
| the chemistry of precipitation, throughfall and stemflow in two holm oak (quercus ilex l.) forests under a contrasted pollution environment in ne spain. | atmospheric deposition was studied through measurements of bulk deposition, throughfall and stemflow at two sites of contrasted exposure to pollution in the montseny mountains (northeastern spain). to explore the contribution of local or distant sources at both sites, concentration data and precipitation amounts (log transformed) for both bulk deposition and net throughfall were fitted by linear regression. these models indicated the more important contribution of washout scavenging processes an ... | 2003 | 12670768 |
| soil persistence and biodiversity of ericoid mycorrhizal fungi in the absence of the host plant in a mediterranean ecosystem. | the occurrence of suitable mycorrhizal inocula may be an important factor affecting the dynamics of plant communities. we investigated the persistence and diversity of ericoid mycorrhizal fungi in the soil of a mature quercus ilex forest where ericaceous hosts were absent. erica arborea was used as a bait plant and results were compared to soil samples from experimental plots where cuttings had allowed reappearance of this ericaceous species. fungal endophytes were isolated and tested in mycorrh ... | 2003 | 12682828 |
| epiphytic lichens as sentinels for heavy metal pollution at forest ecosystems (central italy). | the results of a study using epiphytic lichens (parmelia caperata) as sentinels for heavy metal deposition at six selected forest ecosystems of central italy are reported. the woods investigated are characterized by holm oak (quercus ilex), turkey oak (quercus cerris) and beech (fagus sylvatica) and represent the typical forest ecosystems of central italy at low, medium and high elevations, respectively. the results showed that levels of heavy metals in lichens were relatively low and consequent ... | 2003 | 12685761 |
| fruit abortion, developmental selection and developmental stability in quercus ilex. | fruit abortion has been hypothesized to be a parental means of selective removal of propagules with low viability. in particular, aborted zygotes have been suggested to have developmentally deviant phenotypes, and surviving offspring may therefore give rise to adults with a developmentally stable phenotype. we tested predictions from this hypothesis using acorns of holm oaks quercus ilex as a model system. fecundity of oak trees was negatively related to mean fluctuating asymmetry of leaves, and ... | 2003 | 12721827 |
| 12co2 emission from different metabolic pathways measured in illuminated and darkened c3 and c4 leaves at low, atmospheric and elevated co2 concentration. | the detection of 12co2 emission from leaves in air containing 13co2 allows simple and fast determination of the co2 emitted by different sources, which are separated on the basis of their labelling velocity. this technique was exploited to investigate the controversial effect of co2 concentration on mitochondrial respiration. the 12co2 emission was measured in illuminated and darkened leaves of one c4 plant and three c3 plants maintained at low (30-50 ppm), atmospheric (350-400 ppm) and elevated ... | 2003 | 12773522 |
| phylogeographical variation of chloroplast dna in holm oak (quercus ilex l.). | variation in the lengths of restriction fragments (rflps) of the whole chloroplast dna molecule was studied in 174 populations of quercus ilex l. sampled over the entire distribution of this evergreen and mainly mediterranean oak species. by using five endonucleases, 323 distinct fragments were obtained. from the 29 and 17 cpdna changes identified as site and length mutations, respectively, 25 distinct chlorotypes were distinguished, mapped and treated cladistically with a parsimony analysis, us ... | 2002 | 12406243 |
| sap flow of three co-occurring mediterranean woody species under varying atmospheric and soil water conditions. | we studied the seasonal patterns of water use in three woody species co-occurring in a holm oak forest in northeastern spain. the three species studied, quercus ilex l., phillyrea latifolia l. and arbutus unedo l., constitute more than 99% of the total basal area of the forest. the study period included the dry seasons of 1999 and 2000. water use was estimated with granier-type sap flux sensors. standard meteorological variables, soil water content and leaf water potentials were also monitored. ... | 2003 | 12839728 |
| stomatal responses to drought at a mediterranean site: a comparative study of co-occurring woody species differing in leaf longevity. | we studied stomatal responses to decreasing predawn water potential (psipd) and increasing leaf-to-air water vapor pressure difference (vpd) of co-occurring woody mediterranean species with contrasting leaf habits and growth form. the species included two evergreen oaks (quercus ilex subsp. ballota (desf.) samp. and q. suber l.), two deciduous oaks (q. faginea lam. and q. pyrenaica willd.) and two deciduous shrubs (pyrus bourgaeana decne. and crataegus monogyna jacq.). our main objective was to ... | 2003 | 12952785 |
| tracing carbon uptake from a natural co2 spring into tree rings: an isotope approach. | we analyzed 14c, 13c and 18o isotope variations over a 50-year period in tree rings of quercus ilex l. trees growing at a natural co2 spring in a mediterranean ecosystem. we compared trees from two sites, one with high and one with low exposure to co2 from the spring. the spring co2 is free of 14c. thus, this carbon can be traced in the wood, and the amount originating from the spring calculated. the amount decreased over time, from about 40% in 1950 to 15% at present for the site near the sprin ... | 2003 | 12952786 |
| cryopreservation of quercus suber and quercus ilex embryonic axes: in vitro culture, desiccation and cooling factors. | this study examines different factors included in the cryopreservation protocols for quercus ilex and q. suber embryonic axes. in vitro incubation temperature played an important role in the appropriate development of q. ilex axes, as 15 degrees c was superior to 25 degrees c. q. suber axes proved to be more sensitive to desiccation and cooling. poor survival (35%) was observed when axes were included into cryovials and then in liquid nitrogen, and none when immersed in sub-cooled liquid nitroge ... | 2002 | 12447487 |
| effects of tension wood on specific conductivity and vulnerability to embolism of quercus ilex seedlings grown at two atmospheric co2 concentrations. | to determine whether there are decreases in hydraulic function of a woody stem when it has increased mechanical loading, quercus ilex l. seedlings were grown upright or inclined to force the production of large amounts of tension wood (tw). seedlings were grown in ambient or elevated carbon dioxide concentrations ([co2]) for 16-17 months to provide two sets of seedlings differing in growth rates and allocation patterns. in both co2 environments, inclination caused formation of large amounts of t ... | 2003 | 12642240 |
| assessment of nutritional status and trace element contamination of holm oak woodlands through analyses of leaves and surrounding soils. | the nutritional status and trace element contamination of holm oak woodlands in vesuvius national park were assessed by analyses of quercus ilex l. leaves and surrounding soils. the concentrations of cd, cr, cu, fe, k, mg, mn, na, ni, pb, v and zn were measured in 1-year-old leaves, and in the soils at 0-5 and 15-20 cm depths. the potentially available concentrations were also measured for the soils. the leaf element concentrations were similar to the q. ilex chemical fingerprint, thus indicatin ... | 2003 | 12826392 |
| biomonitoring of trace element air contamination at sites in campania (southern italy). | surface soils and one-year-old quercus ilex l. leaves were investigated for element concentrations to evaluate the air quality of some sites in campania (southern italy). sampling was carried out at 7 natural and 7 urban sites from september 1998 to february 1999. the investigated elements were cd, cr, cu, fe, mn, ni, pb, v and zn. at the urban sites, cr, cu, fe, ni and pb leaf concentrations were on average two fold higher than at the natural sites. cu, pb and zn soil concentrations were also h ... | 2003 | 14650629 |
| changes in soil and leaf trace element concentrations: a study in naples city centre. | the spatial and temporal changes of trace element concentrations in leaves and soils of an urban area were investigated simultaneously. for this purpose, in may and september 2001 and in january and may 2002, samples of quercus ilex leaves and surrounding soils were taken at 5 sites in central naples and on mt. vesuvius, a remote area, as control. the contents of cd, cr, cu, fe, mn, pb, v and zn were analysed in both matrices by atomic absorption spectrometry. the urban sites in naples showed di ... | 2003 | 14650632 |
| delta(13)c and tree-ring width reflect different drought responses in quercus ilex and pinus halepensis. | holm oak (quercus ilexl.) and aleppo pine (pinus halepensismill) are representative of two different functional types of trees extensively found in the mediterranean: evergreen sclerophyllous and drought-adapted conifers. the former is considered a partially drought-tolerant species, whereas the latter is a typically drought-avoiding, water-saving species. we postulated that contrasting strategies in response to water deficits in q. ilex and p. halepensis would lead to a differential sensitivity ... | 2003 | 14505023 |
| impact of ozone on monoterpene emissions and evidence for an isoprene-like antioxidant action of monoterpenes emitted by quercus ilex leaves. | quercus ilex (l.) leaves emit monoterpenes, particularly alpha-pinene, beta-pinene and sabinene. apart from the monoterpene pools that are stored in specialized structures and have a clear defensive or attractive role, the function of monoterpenes in q. ilex leaves is unknown. we tested whether monoterpenes have an antioxidant role, as has previously been found for isoprene in isoprene-emitting leaves. we exposed q. ilex leaves to either mild and repeated ozone exposure (experiment i) or to a si ... | 2004 | 14757575 |
| site-specific water relations and stomatal response of quercus ilex in a mediterranean watershed. | intraspecific variations in the water relations and stomatal response of quercus ilex l. were analyzed under field conditions by comparing trees at two locations within a mediterranean watershed (l'avic, catalonia, ne spain). distinct environmental gradients exist between the two sites (referred to as ridge top at 975 m and valley bottom at 700 m) with greater soil depth for water storage, reduced radiation, reduced wind and higher water vapor pressure deficits at the valley bottom than at the r ... | 1994 | 14967677 |
| phenolic compounds and fatty acids from acorns (quercus spp.), the main dietary constituent of free-ranged iberian pigs. | the aim of the present work was to identify and quantify the phenolic compounds and fatty acids in acorns from quercus ilex, quercus rotundifolia, and quercus suber. the concentration of oleic acid was >63% of total fatty acids in all cases, followed by palmitic and linoleic acids at similar concentrations (12-20%). the concentrations of alpha-tocopherol in q. rotundifolia, q. ilex, and q. suber were 19, 31, and 38 mg/kg of dry matter (dm), respectively, whereas the concentrations of gamma-tocop ... | 2003 | 14518951 |
| thinning effects on carbon allocation to fine roots in a quercus ilex forest. | the dynamics of the fine root system are relevant to calculations of the carbon balance of the ecosystem, and there is also a need to quantify changes in this component caused by disturbances. mediterranean forest systems have historically been coppiced to obtain charcoal. as a result of the resprouting capacity of holm oaks (quercus ilex l.), these forests present more than 50% of their biomass below ground (stump + roots > 1 cm in diameter), but the effects of thinning on the fine root system ... | 2003 | 14597431 |
| removal of toxic metals from solution by leaf, stem and root phytomass of quercus ilex l. (holly oak). | increased consciousness for safeguarding the aqueous environment has prompted a search for alternative technologies for the removal of toxic metal ions from aqueous solutions. in this regard, a wide variety of biomass is being considered as adsorbents of heavy metals for treatment of industrial and domestic wastewaters as well as natural waters, including drinking water. in the present investigation, the potential of quercus ilex phytomass from stem, leaf and root as an adsorbent of chromium (cr ... | 2000 | 15092842 |
| relationship between leaf life-span and photosynthetic activity of quercus ilex in polluted urban areas (rome). | anatomical, morphological and physiological leaf traits of quercus ilex in response to different traffic levels (high traffic level, type a sites; average traffic level, type b sites; control sites, type c sites) were analysed in rome. superficial leaf deposits were analysed comparing unwashed and washed leaf samples. washing lowered pb 61% in a, 54% in b and 27% in c. sr, fe, cu, zn and al showed the same trend as pb. the higher photosynthetic activity of 1-year-old leaves (pn=7.0+/-2.9 micromo ... | 2000 | 15092853 |
| temporal and spatial variation in c, n, s and trace element contents in the leaves of quercus ilex within the urban area of naples. | this paper presents a comparative analysis of the concentrations of c, n and s and several trace elements (fe, mn, na, zn, cu, v, pb, ni, cr, cd) in leaves of quercus ilex, an evergreen oak, collected in the urban area of naples in 1989 and 1996. the samplings were carried out from 25 urban sites (roads with different traffic flows as well as urban and suburban parks) and from two remote areas as controls. relative to 1989, the values measured in 1996 denote a strong decrement of s, fe, na, pb, ... | 2000 | 15092919 |
| biomonitoring of airborne metals in urban environments: new tracers of vehicle emission, in place of lead. | samples of quercus ilex leaves and of the inhalable fraction of atmospheric particulate (pm(10)) were collected along a busy road and in a park in florence (italy). quantitative comparisons and correlations of element concentrations in pm(10) collected by air samplers at two sites showed that ba, cu, fe, mn, pb and zn were the main metal pollutants emitted by vehicles in florence. very similar results were obtained by the analysis of q. ilex leaves which were found to accumulate airborne metals ... | 2000 | 15092978 |
| antimicrobial effects of quercus ilex l. extract. | the antimicrobial activities of the methanol extract of quercus ilex l. (pirnal oak) leaves were tested in vitro against a wide range of human and plant-associated microorganisms. a total of 132 microbial organisms belonging to 55 bacteria and five fungi and yeast species were studied using a disc-diffusion method and microdilution assays. the results were evaluated as inhibition zones around the disc impregnated with q. ilex extract at a concentration of 300 micro l/ml. the results showed that ... | 2004 | 15103667 |
| analysis of serpentinophytes from north-east of portugal for trace metal accumulation--relevance to the management of mine environment. | in north-east of portugal, the serpentinized area is about 8000 ha with a characteristic geology and flora. the serpentine plant community and respective soils were analyzed to examine the trace metal budget in different tissues of the plants exhibiting resistance to trace metals. one hundred and thirty five plant species belonging to 39 families and respective soils have been analyzed for total co, cr, cu, fe, mn, ni, pb and zn. substantial amounts of ni, cr, co and mn were detected in plant ti ... | 2004 | 14675842 |
| drought tolerance and transplanting performance of holm oak (quercus ilex) seedlings after drought hardening in the nursery. | drought stress is the main cause of mortality of holm oak (quercus ilex l.) seedlings in forest plantations. we therefore assessed if drought hardening, applied in the nursery at the end of the growing season, enhanced the drought tolerance and transplanting performance of holm oak seedlings. seedlings were subjected to three drought hardening intensities (low, moderate and severe) for 2.5 and 3.5 months, and compared with control seedlings. at the end of the hardening period, water relations, g ... | 2004 | 15294761 |
| airborne ethylene may alter antioxidant protection and reduce tolerance of holm oak to heat and drought stress. | plant-emitted ethylene has received considerable attention as a stress hormone and is considered to play a major role at low concentrations in the tolerance of several species to biotic and abiotic stresses. however, airborne ethylene at high concentrations, such as those found in polluted areas (20-100 nl l(-1)) for several days, has received far less attention in studies of plant stress tolerance, though it has been shown to alter photosynthesis and reproductive stages (seed germination, flowe ... | 2004 | 15448201 |
| herbivore effects on developmental instability and fecundity of holm oaks. | plants are able to compensate for loss of tissue due to herbivores at a variety of spatial and temporal scales, masking detrimental effects of herbivory on plant fitness at these scales. the stressing effect of herbivory could also produce instability in the development of plant modules, and measures of such instability may reflect the fitness consequences of herbivory if instability is related to components of plant fitness. we analyse the relationships between herbivory, developmental instabil ... | 2004 | 14968355 |
| trace element analyses in an epiphytic lichen and its bark substrate to assess suitability for air biomonitoring. | total concentrations of cd, cr, fe, ni, pb and zn were compared from october 1996 to april 1998 in physcia biziana (massal.) zhalbr. v. leptophylla vezda and in the bark of quercus ilex l. sampled from the same trees at an urban park. trace metal concentrations were also measured in the bark covered by the lichen thalli. the lichens showed significantly higher cr, fe, ni and zn concentrations than both uncovered and covered barks. by contrast, both types of barks had higher concentrations of cd ... | 2004 | 15473529 |
| habitat quality as a predictor of spatial variation in blue tit reproductive performance: a multi-plot analysis in a heterogeneous landscape. | vertebrate studies have rarely investigated the influence of spatial variation in habitat richness on both short-term (breeding) and long-term (offspring recruitment) reproductive performance using simultaneously multi-patch, multi-habitat type and multi-year approaches at landscape level. here we present results of such an approach using the influence of two oak tree (quercus ilex, q. humilis) species on reproductive performance in corsican blue tits (parus caeruleus ogliastrae) as a model syst ... | 2004 | 15549399 |
| bigger is not always better: conflicting selective pressures on seed size in quercus ilex. | most theoretical treatments of the evolutionary ecology of offspring size assume a simple and direct effect of investment per offspring on offspring fitness. in this paper i experimentally determine the relationship between seed mass and several main fitness components of the oak quercus ilex, to estimate phenotypic selection acting on seed mass during the early life cycle and to discover any potential selective conflicts occurring between different stages from dispersal to establishment. i foun ... | 2004 | 15058720 |
| ozone monitoring in a mediterranean forest using diffusive and continuous sampling. | ambient ozone was measured in a forest in castelporziano (italy) characterised by the prevailing presence of holm-oak trees (quercus ilex l.) from june to november 2003. two methods for measuring ozone were used: long-term monitoring using diffusive samplers at three heights within the canopy, and continuous monitoring at two heights using the uv method. results for one week mean ozone levels above and below the canopy from the diffusive samplers were compared to those obtained using the automat ... | 2004 | 15452678 |
| stomatal limitation to co2 assimilation and down-regulation of photosynthesis in quercus ilex resprouts in response to slowly imposed drought. | holm oak (quercus ilex l.) is native to hot, dry mediterranean forests where limited water availability often reduces photosynthesis in many species, and forest fires are frequent. holm oaks resprout after a disturbance, with improved photosynthetic activity and water relations compared with unburned plants. to better understand the role of water availability in this improvement, watering was withheld from container-grown plants, either intact (controls) or resprouts after excision of the shoot, ... | 2004 | 15123453 |
| seasonal changes in photosynthesis and photoprotection in a quercus ilex subsp. ballota woodland located in its upper altitudinal extreme in the iberian peninsula. | quercus ilex l. subsp. ballota (desf.) samp., a mediterranean evergreen species growing in a continental mediterranean climate, did not experience water stress and showed greater sensitivity to winter stress than to summer stress over a 12-month period. net co2 assimilation rates and photosystem ii (psii) efficiency decreased markedly during the cold months and recovered completely in spring. lutein, neoxanthin and beta-carotene to chlorophyll (chl) molar ratios all showed the same trend through ... | 2005 | 15741152 |
| diversity and specificity of ectomycorrhizal fungi retrieved from an old-growth mediterranean forest dominated by quercus ilex. | we analysed the ectomycorrhizal (ecm) fungal diversity in a mediterranean old-growth quercus ilex forest stand from corsica (france), where arbutus unedo was the only other ecm host. on a 6400 m2 stand, we investigated whether oak age and host species shaped below-ground ecm diversity. ectomycorrhizas were collected under q. ilex individuals of various ages (1 yr seedlings; 3-10 yr saplings; old trees) and a. unedo. they were typed by its-rflp analysis and identified by match to rflp patterns of ... | 2005 | 15869659 |
| post-fire, seasonal and annual dynamics of the ectomycorrhizal community in a quercus ilex l. forest over a 3-year period. | two study plots, burned and control, were established in autumn 1998 in a quercus ilex forest located in northern spain, part of which had been affected by a low intensity fire in 1994. soil samples for ectomycorrhizae (ecm) were taken over a 3-year period in each study plot in spring, summer, autumn and winter. ecm morphotypes were identified and the relative abundance of each morphotype in each soil sample calculated, along with species richness, shannon diversity index and percentage of mycor ... | 2005 | 15889285 |
| nitrogen transport in the xylem sap of quercus ilex: the role of ornithine. | the storage and remobilization of nitrogen in deciduous and evergreen species is a major source of n, supporting the seasonal growth of trees. in evergreens, in addition to wood and roots, older leaves are important reservoirs of n used in the growth of new foliage. just before bud burst, when transpiration is inactive or low, and when uptake of nitrogen by the roots may be restricted due to low temperatures, levels of organic n in the xylem are high. amino acids usually comprise the bulk of thi ... | 2005 | 15940878 |
| [sensitization to castanea sativa pollen and pollinosis in northern extremadura (spain)]. | castanea sativa pollen allergy has generally been considered to be uncommon and clinically insignificant. in our geographical area (plasencia, cáceres, spain) castanea sativa pollen is a major pollen. | 2005 | 15946627 |
| statistical and geostatistical modelling of preliminarily adjusted defoliation on an european scale. | since 1987 tree crown condition is surveyed annually in large parts of europe mainly in terms of defoliation. the plot-wise means of defoliation from 1994 to 2000 were evaluated by general linear models (glm) in order to describe country-specific levels of defoliation and age-trends. additional runs with estimates for influences of insects and fungi were performed. the amount of variance of defoliation explained by country, age and its interaction was between 35% and 59% for the main tree specie ... | 2005 | 15736885 |
| trace element accumulation in the moss hypnum cupressiforme hedw. and the trees quercus ilex l. and pinus halepensis mill. in catalonia. | we studied trace element accumulation in the moss hypnum cupressiforme and the widely distributed mediterranean trees quercus ilex and pinus halepensis located at increasing distances from the barcelona metropolitan area. hypnum cupressiforme, quercus ilex and, to a somewhat lesser extent, pinus halepensis, have proved to be adequate as possible accumulative monitoring species in relation to trace elements pollution. no significant effects of crown orientation were found. one-year old leaves gen ... | 2005 | 16018901 |
| photoinhibition and drought in mediterranean woody saplings: scaling effects and interactions in sun and shade phenotypes. | interacting effects of high light and drought on the performance of sun and shade phenotypes were experimentally undertaken following survival, chlorophyll fluorescence and gas exchange in 2-year-old saplings of four mediterranean trees (quercus ilex and q. coccifera as water-saving species, and pistacia lentiscus and p. terebinthus as water-spending species). half of the saplings were grown in full sunlight and the other half in the shade (6% sunlight). half of each combination of species-pheno ... | 2005 | 15569705 |
| the capacity for thermal protection of photosynthetic electron transport varies for different monoterpenes in quercus ilex. | heat stress resistance of foliar photosynthetic apparatus was investigated in the mediterranean monoterpene-emitting evergreen sclerophyll species quercus ilex. leaf feeding with fosmidomycin, which is a specific inhibitor of the chloroplastic isoprenoid synthesis pathway, essentially stopped monoterpene emission and resulted in the decrease of the optimum temperature of photosynthetic electron transport from approximately 38 degrees c to approximately 30 degrees c. the heat stress resistance wa ... | 2005 | 16126854 |
| ozone exposure induces the activation of leaf senescence-related processes and morphological and growth changes in seedlings of mediterranean tree species. | four mediterranean tree taxa, quercus ilex subsp. ilex, quercus ilex subsp. ballota, olea europaea cv. vulgaris and ceratonia siliqua, were exposed to different ozone (o(3)) concentrations in open top chambers (otcs) during 2 years. three treatments were applied: charcoal-filtered air (cf), non-filtered air (nf) and non-filtered air plus 40 ppb(v) of o(3) (nf +). the photochemical maximal efficiency, fv/fm, decreased in nf + plants during the second year of exposure, especially during the most s ... | 2005 | 15589656 |
| temporal variations in pah concentrations in quercus ilex l. (holm oak) leaves in an urban area. | temporal variations of polycyclic aromatic hydrocarbon (pah) concentrations in leaves of a mediterranean evergreen oak, quercus ilex l., were investigated in order to assess the suitability of this species to biomonitor pah air contamination. leaf samples were collected at six sites of the urban area of naples (italy) and at a control site in the vesuvius national park, in may and september 2001, and in january and may 2002. pah extraction was conducted by sonication in dichloromethane-acetone a ... | 2005 | 16182861 |
| tissue-water relations of two co-occurring evergreen mediterranean species in response to seasonal and experimental drought conditions. | tissue-water relations were used to characterize the responses of two mediterranean co-occurring woody species (quercus ilex l. and phillyrea latifolia l.) to seasonal and experimental drought conditions. soil water availability was reduced approximately 15% by partially excluding rain throughfall and lateral flow (water runoff). seasonal and experimental drought elicited physiological and morphological adaptations other than osmotic adjustment: both species showed large increases in cell-wall e ... | 2005 | 16044197 |
| real-time pcr detection of biscogniauxia mediterranea in symptomless oak tissue. | real-time pcr, based on taqman chemistry, was used to detect biscogniauxia mediterranea, a fungal pathogen that after a long endophytic phase may cause charcoal disease in oak trees. | 2005 | 15960754 |
| dynamics of the enhanced emissions of monoterpenes and methyl salicylate, and decreased uptake of formaldehyde, by quercus ilex leaves after application of jasmonic acid. | jasmonic acid (ja) is a signalling compound with a key role in both stress and development in plants, and is reported to elicit the emission of volatile organic compounds (vocs). here we studied the dynamics of such emissions and the linkage with photosynthetic rates and stomatal conductance. we sprayed ja on leaves of the mediterranean tree species quercus ilex and measured the photosynthetic rates, stomatal conductances, and emissions and uptake of vocs using proton transfer reaction mass spec ... | 2006 | 16390425 |
| detection of tuber melanosporum dna in soil. | our objectives were (i) to develop a molecular method to detect mycelia of tuber melanosporum (black truffle) in soil and (ii) to test for mycelial distribution around two truffle-bearing quercus ilex trees in a truffle orchard. isolation of total dna from soil was performed, followed by pcr amplification with t. melanosporum-specific primers and restriction analysis. to address the detection sensitivity level, soil samples were inoculated with known amounts of gleba of t. melanosporum. the dete ... | 2006 | 16445753 |
| summer and winter sensitivity of leaves and xylem to minimum freezing temperatures: a comparison of co-occurring mediterranean oaks that differ in leaf lifespan. | freezing sensitivity of leaves and xylem was examined in four co-occurring mediterranean oaks (quercus spp.) grown in a common garden to determine whether freezing responses of leaves and xylem were coordinated and could be predicted by leaf lifespan. freezing-induced embolism and loss of photosynthetic function were measured after overnight exposure to a range of subzero temperatures in both summer and winter. both measures were found to be dependent on minimum freezing temperature and were cor ... | 2005 | 16313643 |
| differential light responses of mediterranean tree saplings: linking ecophysiology with regeneration niche in four co-occurring species. | the ecophysiological mechanisms underlying plant-plant interactions and forest regeneration processes in mediterranean ecosystems are poorly understood, and the experimental evidence for the role of light availability in these processes is particularly scant. we analyzed the effects of high and low irradiances on 31 ecological, morphological and physiological variables in saplings of four late-successional mediterranean trees, two deciduous (acer opalus subsp. granatense (boiss.) font quer & rot ... | 2006 | 16585040 |
| localized ozone fumigation system for studying ozone effects on photosynthesis, respiration, electron transport rate and isoprene emission in field-grown mediterranean oak species. | we used a localized ozone (o3) fumigation (lof) system to study acute and short-term o(3) effects on physiological leaf traits. the lof system enabled investigation of primary and secondary metabolic responses of similarly and differently aged leaves on the same plant to three different o3 concentrations ([o3]), unconfounded by other influences on o3 sensitivity, such as genetic, meteorological and soil factors. to simulate the diurnal cycle of o3 formation, current-year and 1-year-old quercus i ... | 2005 | 16137938 |
| the use of compost in afforestation of mediterranean areas: effects on soil properties and young tree seedlings. | in mediterranean frequently burnt areas, fire and erosion result in the decrease of soil fertility, so afforestation is a major concern. we carried out an in situ experiment of compost amendment to improve survival and growth of planted tree seedlings. one-year-tree seedlings of native species (quercus ilex, pinus halepensis and pinus pinea) were planted on a frequently burnt calcareous site. three rates of fresh co-composted sewage sludge and greenwastes (control without compost, 20 and 40 kg m ... | 2006 | 16762400 |
| role of species diversity and secondary compound complementarity on diet selection of mediterranean shrubs by goats. | goats foraging on mediterranean shrubs containing secondary compounds (toxins) may consume a variety of shrubs that contain different phytotoxins, thereby increasing shrub intake and avoiding toxicosis. we conducted eight experiments to examine whether goats offered different mixtures of shrubs containing different phytotoxins (tannins and saponins) would consume more shrub biomass than goats offered one shrub a single phytotoxin (tannin or saponin). in the first three experiments, goats fed a m ... | 2006 | 16770718 |
| the biogenic volatile organic compounds emission inventory in france: application to plant ecosystems in the berre-marseilles area (france). | an inventory describing the fluxes of volatile organic compounds (vocs), isoprene and monoterpenes, and other vocs (ovocs) from the biosphere to the atmosphere, has been constructed within the framework of the escompte project (field experiments to constrain models of atmospheric pollution and transport of emissions). the area concerned, located around berre-marseilles, is a mediterranean region frequently subject to high ozone concentrations. the inventory has been developed using a fine scale ... | 2006 | 17011024 |
| soda-anthraquinone, kraft and organosolv pulping of holm oak trimmings. | the operating conditions for an organosolv (ethyleneglycol) and two alkaline (soda-anthraquinone and kraft) processes for obtaining cellulose pulp and paper from holm oak (quercus ilex) wood trimmings were optimized. a range of variation for each process variable (viz. temperature, cooking time and soda or ethyleneglycol concentration) was established and a central composite experimental design involving three independent variables at three different variation levels was applied. the results obt ... | 2006 | 16269242 |
| introduction of the factor of partitioning in the lithogenic enrichment factors of trace element bioaccumulation in plant tissues. | bioindicators are widely used in the study of trace elements inputs into the environment and great efforts have been conducted to separate atmospheric from soil borne inputs on biomass accumulation. many monitoring studies of trace element pollution take into account the dust particles located in the plant surface plus the contents of the plant tissues. however, it is usually only the trace element content in the plant tissues that is relevant on plant health. enrichment factor equations take in ... | 2006 | 16648953 |
| complex adjustments of photosynthetic potentials and internal diffusion conductance to current and previous light availabilities and leaf age in mediterranean evergreen species quercus ilex. | mature non-senescent leaves of evergreen species become gradually shaded as new foliage develops and canopy expands, but the interactive effects of integrated light during leaf formation (q(int)g), current light (q(int)c) and leaf age on foliage photosynthetic competence are poorly understood. in quercus ilex l., we measured the responses of leaf structural and physiological variables to q(int)c and q(int)g for four leaf age classes. leaf aging resulted in increases in leaf dry mass per unit are ... | 2006 | 17080941 |
| drought changes the dynamics of trace element accumulation in a mediterranean quercus ilex forest. | we conducted a field drought manipulation experiment in an evergreen oak mediterranean forest from 1999 to 2005 to investigate the effects of the increased drought predicted for the next decades on the accumulation of trace elements that can be toxic for animals, in stand biomass, litter and soil. drought increased concentrations of as, cd, ni, pb and cr in roots of the dominant tree species, quercus ilex, and leaf cd concentrations in arbutus unedo and of phillyrea latifolia codominant shrubs. ... | 2007 | 17137692 |
| sensitivity of volatile monoterpene emission to changes in canopy structure: a model-based exercise with a process-based emission model. | this paper investigates the dependence of monoterpene emissions at the canopy scale on total leaf area and leaf distribution. simulations were carried out for a range of hypothetical but realistic forest canopies of the evergreen quercus ilex (holm oak). two emission models were applied that either did (sim-bim2) or did not (g93) account for cumulative responses to temperature and light. both were embedded into a canopy model that considered spatial and temporal variations of foliage properties. ... | 2007 | 17244049 |
| water-use strategies in two co-occurring mediterranean evergreen oaks: surviving the summer drought. | in the mediterranean evergreen oak woodlands of southern portugal, the main tree species are quercus ilex ssp. rotundifolia lam. (holm oak) and quercus suber l. (cork oak). we studied a savannah-type woodland where these species coexist, with the aim of better understanding the mechanisms of tree adaptation to seasonal drought. in both species, seasonal variations in transpiration and predawn leaf water potential showed a maximum in spring followed by a decline through the rainless summer and a ... | 2007 | 17331898 |
| variation in cold hardiness and carbohydrate concentration from dormancy induction to bud burst among provenances of three european oak species. | although cold hardiness is known to be a major determinant of tree species distribution, its dynamics and the factors that regulate it remain poorly understood. variation in cold hardiness and carbohydrate concentration, from dormancy induction until bud burst, were investigated in populations of two deciduous (quercus robur l. and quercus pubescens willd.) and one evergreen (quercus ilex l.) european oak. mean cold hardiness values in january were -56, -45 and -27 degrees c for q. robur, q. pub ... | 2007 | 17331900 |
| evaluating high time-resolved changes in carbon isotope ratio of respired co2 by a rapid in-tube incubation technique. | recent insights into fractionation during dark respiration and rapid dynamics in isotope signatures of leaf- and ecosystem-respired co(2) indicate the need for new methods for high time-resolved measurements of the isotopic signature of respired co(2) (delta(13)c(res)). we present a rapid and simple method to analyse delta(13)c(res) using an in-tube incubation technique and an autosampler for small septum-capped vials. the effect of storage on the delta(18)o and delta(13)c ratios of ambient co(2 ... | 2007 | 17348086 |
| pulping of holm oak wood. influence of the operating conditions. | this paper reports on the influence of independent variables in the pulping of holm oak wood (quercus ilex l.) [viz. temperature (135-195 degrees c), cooking time (30-90min) and soda concentration (10-20%)] on the yield, holocellulose content, alpha-cellulose content, brightness and viscosity of the resulting pulp. by using a central composite factorial design, equations relating each dependent variable to the different independent variables were derived that reproduced the experimental results ... | 2008 | 17350828 |
| dimethylallyl diphosphate and geranyl diphosphate pools of plant species characterized by different isoprenoid emissions. | dimethylallyl diphosphate (dmadp) and geranyl diphosphate (gdp) are the last precursors of isoprene and monoterpenes emitted by leaves, respectively. dmadp and gdp pools were measured in leaves of plants emitting isoprene (populus alba), monoterpenes (quercus ilex and mentha piperita), or nonemitting isoprenoids (prunus persica). detectable pools were found in all plant species, but p. persica showed the lowest pool size, which indicates a limitation of the whole pathway leading to isoprenoid bi ... | 2006 | 16461390 |
| parameterization of the stomatal component of the do3se model for mediterranean evergreen broadleaf species. | an ozone (o3) deposition model (do3se) is currently used in europe to define the areas where o3 concentrations lead to absorbed o3 doses that exceed the flux-based critical levels above which phytotoxic effects would be likely recorded. this mapping exercise relies mostly on the accurate estimation of o3 flux through plant stomata. however, the present parameterization of the modulation of stomatal conductance (g(s)) behavior by different environmental variables needs further adjustment if o3 ph ... | 2007 | 17450288 |
| antibacterial activity of quercus ilex bark's extracts. | the antibacterial activity of different extracts of quercus ilex bark (fagaceae) was studied in vitro against seven reference strains of bacteria by using a disc-diffusion method and agar-dilution method. the ethyl acetate extract (qe), n-butanol extract (qb) and final aqueous layer (qa) were effective against all bacterial strains tested at mics ranging from 128 to 512 microg/ml. the n-hexane extract (qh) and dichloromethane extract (qd) showed no activity. | 2007 | 17513077 |