Bioclimatic requirements for olive flowering in two Mediterranean regions located at the same latitude (Andalucia, Spain and Sicily, Italy).
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The Mediterranean Region is the major area devoted to olive tree crop, and therefore a study of olive flowering is of great interest for the European Community. On the other hand, olive pollen is one of the main causes of pollen allergy in the Mediterranean area. Olive flowering is affected by climatic factors such as temperature and photoperiod, which vary geographically in latitude and altitude. Temperature has been used to study those processes that lead to flowering in the olive tree. The aim of the present paper is firstly the comparison of the flowering full bloom dates in two Mediterranean areas, Sicily (Italy) and Cordoba (Spain), located in the same latitudinal band (37-38 degrees N) and to calculate the heat requirement until flowering by determination of different threshold temperatures and methods of heat accumulation. A delay of the full flowering dates in the Spanish compared with the Italian olive groves was observed. The most suitable threshold temperatures were carried out in a 7 degrees -15 degrees C range by considering the heat accumulation start on 1 January in each olive grove. In particular, some causes were indicated as responsible for the different threshold temperatures recorded in the 2 study areas: First, the different climatic conditions (continental and insular climate) secondly the different cultivars present in the olive groves. (+info)
Airborne ragweed pollen concentration in north-eastern Croatia and its relationship with meteorological parameters.
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Airborne ragweed pollen concentration in the north-eastern part of Croatia was investigated in relation to some meteorological factors. Data was obtained for three consecutive years (2001, 2002 and 2003) using volumetric method (Burkard trap). The correlation between the concentration of pollen grains in the atmosphere and maximum, minimum and mean daily temperature, daily temperature range, sunshine hours, relative humidity and precipitation from daily monitoring was studied. The critical ragweed pollen season appears from 33rd to 38th week, with its peak at the beginning of September each year. Statistically significant correlation between the ragweed pollen count and selected meteorological variables were found in some study years, but only a correlation with the mean air temperature and ragweed pollen presence in the air was significant over time. (+info)
Aerobiological investigation in Bitlis, Turkey.
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A continuous aeropalynological survey of the atmosphere of Bitlis was carried out from January 2001 to December 2002 by means of the gravimetric method using Durham apparatus. Weekly pollen grains in per cm(2) were calculated. During two years, a total of 3,323 pollen grains/cm(2) which belong to 46 taxa, 21 of total belong to arboreal (AP) and 25 of total non-arboreal (NAP) plants, and unidentified pollen grains were recorded. In 2001, 1,833 pollen grains and in 2002, 1,490 pollen grains were recorded. Total pollen grains consist of 39.39 % AP, 59.28 % NAP plants and 1.32 % unidentified pollen grains. Gramineae, Urticaceae, Juglans spp., Quercus spp., Umbellifereae, Cupressaceae/Taxaceae, Fraxinus spp., Salix spp., Plantago spp., Pinus spp., Rumex spp., Moraceae and Chenopodiaceae/Amaranthaceae were responsible for the greatest amounts of pollens in the investigated region. 58.38 % of total pollen grains were appeared during May and June. (+info)
Responses of grassland production to single and multiple global environmental changes.
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In this century, increasing concentrations of carbon dioxide (CO2) and other greenhouse gases in the Earth's atmosphere are expected to cause warmer surface temperatures and changes in precipitation patterns. At the same time, reactive nitrogen is entering natural systems at unprecedented rates. These global environmental changes have consequences for the functioning of natural ecosystems, and responses of these systems may feed back to affect climate and atmospheric composition. Here, we report plant growth responses of an ecosystem exposed to factorial combinations of four expected global environmental changes. We exposed California grassland to elevated CO2, temperature, precipitation, and nitrogen deposition for five years. Root and shoot production did not respond to elevated CO2 or modest warming. Supplemental precipitation led to increases in shoot production and offsetting decreases in root production. Supplemental nitrate deposition increased total production by an average of 26%, primarily by stimulating shoot growth. Interactions among the main treatments were rare. Together, these results suggest that production in this grassland will respond minimally to changes in CO2 and winter precipitation, and to small amounts of warming. Increased nitrate deposition would have stronger effects on the grassland. Aside from this nitrate response, expectations that a changing atmosphere and climate would promote carbon storage by increasing plant growth appear unlikely to be realized in this system. (+info)
Genecology of Douglas fir in western Oregon and Washington.
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BACKGROUND AND AIMS: Genecological knowledge is important for understanding evolutionary processes and for managing genetic resources. Previous studies of coastal Douglas fir (Pseudotsuga menziesii var. menziesii) have been inconclusive with respect to geographical patterns of variation, due in part to limited sample intensity and geographical and climatic representation. This study describes and maps patterns of genetic variation in adaptive traits in coastal Douglas fir in western Oregon and Washington, USA. METHODS: Traits of growth, phenology and partitioning were measured in seedlings of 1338 parents from 1048 locations grown in common gardens. Relations between traits and environments of seed sources were explored using regressions and canonical correlation analysis. Maps of genetic variation as related to the environment were developed using a geographical information system (GIS). KEY RESULTS: Populations differed considerably for adaptive traits, in particular for bud phenology and emergence. Variation in bud-set, emergence and growth was strongly related to elevation and cool-season temperatures. Variation in bud-burst and partitioning to stem diameter versus height was related to latitude and summer drought. Seedlings from the east side of the Washington Cascades were considerably smaller, set bud later and burst bud earlier than populations from the west side. CONCLUSIONS: Winter temperatures and frost dates are of overriding importance to the adaptation of Douglas fir to Pacific Northwest environments. Summer drought is of less importance. Maps generated using canonical correlation analysis and GIS allow easy visualization of a complex array of traits as related to a complex array of environments. The composite traits derived from canonical correlation analysis show two different patterns of variation associated with different gradients of cool-season temperatures and summer drought. The difference in growth and phenology between the westside and eastside Washington Cascades is hypothesized to be a consequence of the presence of interior variety (P. menziessii var. glauca) on the eastside. (+info)
Contamination of malt barley and wheat by Fusarium graminearum and Fusarium culmorum from the crop years 2001-2003 in eastern Croatia.
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This study investigated infection levels with Fusarium graminearum and Fusarium culmorum in malt barley and wheat in eastern Croatia. The contamination was surveyed over three consecutive crop years (2001-2003) on five locations for barley and three wheat cultivating locations. F. graminearum loads reached levels of potentially serious threat for the commercial production of malting raw materials in both cereals (up to 29.1%). On the other hand, the mean percentage of kernels infected with F. culmorum was low to medium (up to 6.1%). The fungal invasions for years and locations were affected by meteorologic and other environmental factors and the pattern seemed to be consistent with species-specific optimal conditions reported by other authors. (+info)
Annual variation of fungal spores in atmosphere of Porto: 2003.
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The seasonal distribution of fungal spore concentration in the city of Porto, Portugal, was continuously studied, from 1 January to 31 December 2003, using a 7-day volumetric Burkard trap. In Portugal, aerobiological studies are scarce, and to our knowledge there are no published data on the atmospheric concentration of fungal spores. The aim of this work therefore is to initiate the aeromycological studies in Porto. The total airborne spore concentration fluctuated between 2 and 2,198 spores/m(3) per day with an daily mean of 403 spores/m(3). The highest airborne spore concentration was found during the summer and the early autumn, while the lowest concentration was registered during the winter. A range of allergenic and phytopathogenic fungal spores was present in the atmosphere of Porto throughout the entire year, although in different concentrations. Among the 22 fungal spore types identified Cladosporium (74.5 %), Ganoderma (11.7 %), Aspergillaceae (2.9 %), Ustilago (2.5 %), Coprinus (1.5 %), Alternaria (1.3 %) and Botrytis (1.3 %) were the most frequent. Seasonally, spore levels of Cladosporium and Alternaria peaked in the autumn and winter, Ganoderma peaked toward autumn, whilst spore levels of the basidiomycete Coprinus fluctuated throughout the year. The total spore concentration was negatively correlated with wind speed and positively correlated with temperature and relative humidity. (+info)
Airborne pollen of Olea in five regions of Portugal.
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The aim of this work was to study spatial and temporal distribution of Olea europeae airborne pollen in different Portuguese regions: Reguengos de Monsaraz (south); Bairrada (west); Braga (northwest); Valenca do Douro and Foz Coa (north-east). Airborne pollen sampling was conducted from 1998-2003 using "Cour" type samplers located in each region. The main pollen season (MPS) of Olea lasted on average 36 days and occurred from late April until middle-to-end of June. During the studied period, inter-annual variations among and within regions, concerning the total annual pollen counts and the beginning, peak and ending dates of the MPS, were reported. Reguengos de Monsaraz and Bairrada registered the earliest MPS starting date, followed by Valenca do Douro and Foz-Coa, and the latest date was verified in Braga that also had the shortest MPS. Reguengos de Monsaraz presented the longest MPS with the highest differences in the beginning and ending dates, but minimum differences in the dates of the maximum pollen peak. Our results showed an increase in the Olea annual pollen index, from north to south, and from the west to the east regions of the country. (+info)