Influence of nearby stands of Artemisia on street-levelversus roof-top-level ratio's of airborne pollen quantities

Among aerobiologists it is commonly accepted that forlong-term monitoring of atmospheric pollen quantities,observations at roof-top level (15–30 m) areappropriate. Yet, possible differences in airbornepollen concentrations at different heights are hardlyinvestigated, particularly in relation to nearbypollen sources. In a six-year survey with twovolumetric pollen traps, airborne concentrations ofpollen from eight selected taxa at roof-top level arecompared with those at street level. For pollen fromplants further away than 1000 m from the street-leveltrap, no difference between quantities of pollen atroof-top and street level is found. Concentrations ofairborne pollen from sources closer than 20 m to thestreet-level trap are 1.2 to 6.8 times higher atstreet level than those at roof-top level,particularly for mugwort (Artemisia). Aftercutting mugwort plants in an area of 100 m around thestreet-level trap, the ratio dropped from 4.8 to 2.7,averagely for the season. It seems that, also in theabsence of nearby sources, airborne mugwort pollenquantities of street level are higher than those atroof-top level but, at least in Leiden, not as much ashas been reported earlier by others.     

A mathematical model for mugwort (Artemisia vulgaris L.) pollen forecasts

Pollen forecasts are a fundamental prerequisite to obtain prophylactic measures for allergic individuals. Mugwort belongs to the most relevant allergenic pollen types after grasses and birch. An approach to modeling of mugwort pollen concentrations has not been attempted previously in Germany. A process-oriented mathematical model for the relative local daily average mugwort airborne pollen concentration was developed on the basis of pollen and weather data measured during a 6-year period. The model depends on the daily minimum and maximum temperature, amount of precipitation and atmospheric pressure, which have to and can be supplied by measurement and prediction. The comparison of modeling results and pollen counting for an additional year confirms the fitness of the model. A computer program was written, which rests upon the model and supplies daily predictions of mugwort pollen flight during the period of the weather forecast. The latter should allow a pollen forecasting period of about 5 days, with an accuracy of about 32–63% explained variance, which in view of the low mugwort pollen counts (nine grains/m³ maximum in the validation year) represents a high relative measurement error. The mathematical model may serve to improve and rationalize of present pollen forecasts.     

Precision of the daily pollen count. Identifying sources of variation using variance component models

Summary During the pollen season, a daily account of airborne pollen is reported by radio and newpapers in Denmark as «Today's pollen count». The Aerobiological Group under the Danish Asthma and Allergy association is responsible for the daily identification and counting of pollen. In 1984 the Group set up a trial to investigate the reproducibility of the pollen count.Three trained pollen counters independently examined the same specimens from two Burkard pollen traps. The traps were located on the roof of the Meterological Institute in Copenhagen 15 meters above ground level in the northern outskirts of central Copenhagen. This is the usual sampling site. Specimens from each trap from 20 days during the grass pollen season were selected. Four species groups were identified in sufficient numbers for statistical analysis. These were, in order of occurrence, spruce/pine (Picea/Pinus), grass (Poaceae), nettle (Urtica) and mugwort (Artemisia).Identification of sources of variation and assessment of their relative importance were carried out using variance components models. A detailed account of the method is given.Qualitatively equivalent conclusions were reached for each group: i) The expected seasonal variation was identified; ii) The counters contributed significantly to the variation of pollen counts; iii) The traps did not contribute to the variance, but a day-trap interaction was identified. This interaction was interpreted. as a problem of instrumental variation over time of traps of variation in meteorological conditions; iv) The total variance was larger than originally expected. The relative uncertainty was greater than 50 per cent.The variance of the daily pollen count cannot be reduced much by reducing counter variation or day-trap interaction. The variation among pollen counters is small, and the day-trap interaction is difficult to fully comprehend. The basic measurement error can be reduced by examining a larger area of each specimen. Although this implies a greater cost, it is probably the most effective method of reducing the uncertainty of «Today's pollen count».     

Airborne behaviour of <Emphasis Type="Italic">Echium</Emphasis> pollen

Species of Echium are clearly entomophilous, but they release great amounts of pollen into the atmosphere with its consequent anemophilous transport, because their high pollen production, the smallness of the grains, and the exserted position of their anthers. Using three volumetric airborne sporetraps in Extremadura (SW of Spain) between 1994 and 1998, we found that Echium pollen reached pollen concentrations similar to or greater than other anemophilous plants. The main pollination period appeared from April to June. The maximum peak daily concentration reached 35.9 grains/m³ and the annual recorded totals showed interannual variations between 64.2 and 614.4. Correlations were calculated between the daily pollen concentrations and the meteorological parameters rain, temperature, wind direction and velocity and relative humidity. Wind direction seems to be significant, warm dry air seems to facilitate the release of pollen into the atmosphere and increase its concentrations. Hourly pollen concentration reached a maximum between 11:00 and 12:00 and a minimum at 07:00, and the patterns were very similar in the three localities studied. This would indicate that the presence of Echium pollen in the atmosphere is related to the processes of anthesis of the populations near the traps, and would not correspond to a model of transport from distant zones.     

Variation of pollen and ovule parameters among different ploidy levels ofCorydalis (Fumariaceae)

The size and number of pollen grains and ovules are compared between 20 populations of different ploidy levels in two self-incompatible species ofCorydalis (Fumariaceae), to test the presence of ploidy-related variation in these reproductive characters. In both species, higher ploidy levels are associated with larger pollen grains, ovules and corolla, but the number of pollen grains and ovules are not different between ploidy levels. The investment per flower is consequently larger at higher ploidy levels, but the flower number per individual is lower, suggesting that the mode of partition of the investment for sexual reproduction varies between different ploidy levels. InC. orthoceras, sex allocation estimated by pollen:ovule ratios in number and volume is more female-biased in polyploids than in diploids. In spite of these variations, the characters studied can not be used as indicators of ploidy level due to the large overlaps between the ploidy levels.     

Comparison of diurnal variation of airborne pollen in Mar del Plata (Argentina)

Intradiurnal variation of arboreal pollen (AP) in Mar del Plata city is compared during three non - consecutive years of survey and described in relation to the associated weather. The daily pattern of pollen abundance has a maximum between 10:00 and 12:00?h, while a minimum occurs at 18:00?h. The first two years of survey showed homogeneous daily trends, but in 1995 the maximum and minimum concentrations were delayed because of the change in position of the collecting station. Arboreal pollen spectrum presented qualitative and quantitative changes in the three years analysed. Results indicate optimal conditions for diurnal dispersion of arboreal pollen are high temperatures and low relative humidity. Also interaction between source position and wind direction has important effects on the timing of the peaks of some pollen types.     

Ragweed and mugwort pollen in Szczecin, Poland

Ragweed (genus Ambrosia) and mugwort (Artemisia vulgaris) pollen grains are known to be very potent aeroallergens, often noted to enter into cross reactions. The aim of the study was to analyse ragweed and mugwort pollen release in Szczecin (western Poland) during the period 2000–2003. Measurements were performed by the volumetric and gravimetric method. Pollen seasons were defined as the periods of 90% of the total catch. Of the 4 years studied, the lowest concentration of ragweed pollen was observed in 2000. In 2000, the annual ragweed pollen count was very high, threefold higher than in 2001. There was a high Ambrosia pollen count in 2003, with the highest daily value of 84 grains/m³. The mugwort pollen season started in the third 10-day period of July and lasted to the end of August in all of the years studied. Analysis of pollen deposition from different Szczecin city’s districts showed that the highest exposure to ragweed pollen allergens occurred in the Majowe district, which is related to the presence of numerous plants of Ambrosia in that district. The mugwort pollen deposition was more abundant in the Żelechowa district, which is an area with villas and gardens. Statistically significant correlations were found between the ragweed pollen count in the air and the maximum wind speed, air temperature and relative humidity and between the mugwort pollen count in the air and air temperature and relative humidity.     

濒危植物大别山五针松母树林花粉传播规律

大别山五针松是典型的风媒传粉植物,花粉流是种群基因流的重要形式。用重力玻片法研究大别山五针松母树林的花粉飞散特征,分析了时间和空间对花粉飞散的影响,结合林分密度和气象因子探讨花粉飞散的特点。结果表明:大别山五针松从5月中旬开始传粉,散粉期为14d,盛粉期为3d,种植密度低的下坡花粉密度比密度大的上坡的要高。日散粉最大值出现在10:00～14:00,植株中上部花粉密度较高,距花粉源50m处花粉密度最高。建议对种植密度大的区域移栽以促进花芽生成,以保证结实率与提高种子品质。     

<Emphasis Type="Italic">Cyperaceae</Emphasis> and <Emphasis Type="Italic">Juncaceae</Emphasis> pollination measured in the air at two sites in SW Spain

The presence of airborne Cyperaceae and Juncaceae pollen was quantified using volumetric aerobiological traps over a 10-year period at two sites in SW Spain separated by 60 km (Badajoz 10 years, Mérida 3 years). The Pearson correlation coefficient was calculated between the daily and hourly concentrations. The values of the principal meteorological parameters—temperature, rainfall, relative humidity, and speed and direction of the wind—were calculated during the study period, and with the accumulated values corresponding to the period prior to pollination. The beginning and ending dates and the duration of the main pollen season (MPS) were also analyzed. Even though both families are anemophilous, the presence of their pollens in the air was low. The annual accumulated daily concentrations were in the range 1.8–15.8 for Juncaceae and 111.8–473.9 for Cyperaceae—values far lower than any other anemophilous pollen type. The Cyperaceae pollen concentration peaked between 09:00 and 12:00. The meteorological factor most closely related to its daily variations was found to be the wind direction, showing that location of the sources is of great importance. The results lend support to the hypothesis of a limitation of allogamous reproduction in favour of vegetative multiplication in both families. Nevertheless, the principal source of the airborne Cyperaceae pollen was found to be Scirpus holoschoenus, whose pollen is distinguishable from the rest. Hence, because of its large production of pollen, this species can be characterized as anemophilous and allogamous. Rainfall in the preceding autumn seemed to be responsible for the amount of Cyperaceae pollen in the air, since a lack of rain was found to be associated with lower densities in the traps. For the Juncaceae, it seems that the temperatures of the preceding December constituted the most limiting meteorological parameter.     

Relationship between pollen emission and fruit production in olive (Olea europaea L.)

Aerobiological data of pollen emission concentrations is used to predict fruit production. The principal aim of this work was to study the relationship between pollen emission patterns, emission homogeneity and fruit production in olive (Olea europaea L.). Data of daily pollen concentrations in the atmosphere during the flowering period, collected over a 20‐year period in Perugia (Central Italy), and the corresponding fruit production data were analysed. Correlation and regression analyses on the partial pollen amounts (subdivisions of the whole flowering period), their statistical variability (expressed as coefficients of variation of the daily pollen concentration), and the production values in the different years demonstrate that pollen emission, during the seven to ten day period immediately preceding the maximum pollen emission day, appears to be most closely related to fruit production. Moreover, the pollen emission homogeneity (minimal variability in daily pollen concentrations) during the “critical” flowering period is very important for fertilization.     

三倍体丹参杂交种的花粉形态研究

三倍体丹参是以二倍体丹参为父本、人工染色体加倍的四倍体白花丹参为母本杂交选育的杂交种。为深入了解三倍体丹参花粉的特性,以及为三倍体种质利用提供孢粉学依据,该文以二倍体丹参为对照,研究了三倍体丹参杂交种花粉的形态变异规律。利用光学显微镜和扫描电镜对二倍体和三倍体丹参的花粉萌发沟、外壁纹饰、花粉粒形状等特征进行了显微和超微形态观察,综合进行了花粉形态差异比较,并对花粉大小和形状数据进行了差异显著性分析和正态检验。结果表明:(1)二倍体丹参为6沟花粉,三倍体花粉萌发沟有6沟和8沟两种类型,沟内疣状颗粒分布不匀,出现畸形萌发沟。(2)二倍体和三倍体花粉外壁均为网状雕纹。二倍体花粉网眼内具多个多边形穿孔,穿孔大; 6沟和8沟两种类型的三倍体花粉网眼无穿孔或仅有几个小穿孔,6沟和8沟花粉的外壁雕纹相同。(3)三倍体花粉的极轴长(P)和赤道宽(E)均值显著小于二倍体花粉,花粉大小呈偏正态分布,P*E的差异系数大于二倍体花粉,且有极值存在。三倍体和二倍体丹参的萌发沟和雕纹存在差异,而花粉形状差异不显著。综上结果表明三倍体丹参花粉在倍性效应和杂合性的双重影响下发生了形态变异,且有多种形态变化。     

Study onPlatanus hispanica Miller pollen content in the air of Seville, southern Spain

The work was carried out using a Cour trap that sampled the air of the city for 8 consecutive years (1987–1994). The pollen ofPlatanus hispanica is the fourth most abundant in the air of Seville (a mean of 11.05% of the total pollen collected). The variation throughout the years in the sum of weekly concentrations ofPlatanus hispanica pollen presents a certain biennial rhythm, in which years of high and low collection of pollen alternate. The starting day of the main pollination period (MPP) is negatively related with the mean of the mean temperatures for February (r=0.73,r ²=0.53,P=0.0398) and is earlier (at the beginning of March) when the mean temperature for February is high, and vice versa. The pattern of pollen variation inPlatanus hispanica remains constant through the years—pollen appears abruptly in high weekly concentrations (> 150 grains/m³) in March (sporadically at the beginning of April), with a week of maximum pollen emission (WMPE) in which more than 50% of the annual pollen is collected (in 6 of the 8 years), and a main pollination period (MPP) of 2 or 3 weeks (except in 1989 when it was 5 weeks). In every year (except 1989), weekly mean temperatures increased during the MPP, the duration of which depends on mean temperature and mean rainfall: mean temperatures > 16°C and absence of rainfall shorten the MPP, while lower temperatures and presence of rainfall lengthen it. The meteorological conditions most often found during the WMPE are mean temperatures > 15°C and rainfall absent or almost so.     

Seasonal fluctuations of the airborne pollen spectrum in Murcia (SE Spain)

During six consecutive years (1993–1998), aBurkard volumetric pollen trap was continuouslyoperated to sample pollen from the air of thecity of Murcia. The aim of the study was toelucidate the spectra of airborne pollen andthe variations during the year, and toelaborate a pollen calendar. This time spanincludes the end of the period with severedrought from 1990–1995, which particularly affected the south-eastern region of Spain.The total sum of daily average pollenconcentrations amounted to 148,645 pollen grainsbelonging to 93 different taxa. A daily averageof 74 pollen grains/m³ and 11 taxa wererecorded, with maxima of 1157 and 27respectively. The total pollen amountregistered in a year correlated with yearlyrainfall, but there was no relation with meanannual temperature. As for annual fluctuations,there seemed to be no influence by totalrainfall or temperature. Spring and winter werethe seasons with the highest pollen counts andpollen diversity.From the 93 identified taxa, 36 are included inthe pollen calendar. Noteworthy findings are:(i) the presence of Thymelaeaceae,Robinia, Betula, Castanea,Zygophyllum, Caryophyllaceae andCannabis, (ii) a long pollen season ofChenopodiaceae/Amaranthaceae, Urticaceae,Poaceae, Arecaceae and Plantago, (iii)the occurrence of summer, autumn and winterflowering of Artemisia, (iv) the lateappearance of Corylus pollen, and (v) theminor presence of Casuarina pollen duringthe mid winter and late spring.     

软质与硬质地表对树木花粉日飘散变化的影响

以油松(Pinus tabulaeformis)、白玉兰(Magnolia denudata)、白皮松(Pinus bungeana)、臭椿(Ailanthus altissima)为被试树种,对比研究了春季静风晴朗天气中软质与硬质两种地表条件下不同树种在距树10m高度1.5m处花粉浓度的日变化特征。研究结果表明:(1)4个树种在相同地表环境的花粉浓度日变化趋势基本一致,但同一树种花粉浓度的日变化特征在软、硬两种地表条件下的差异明显。软质地面一天内空气中花粉浓度最大值出现14:00时前后,04:00时花粉浓度最低,这与全天内空气温度的变化正好一致,而与空气相对湿度的变化恰好相反。硬质地表近地空间空气中的花粉浓度则呈现"双峰型"日变化特征,两次峰值分别出现在14:00时和20:00时,硬质地面花粉浓度20:00时晚高峰的出现时间与硬质地面温度日峰值一致。(2)分析硬质地表20:00时花粉浓度高峰出现的原因可能与硬质地面的散热特性有关,硬质地面夜间释放积蓄热量的过程会在一定程度上增强近地面空气的对流运动,并辅助空气中的花粉粒子不断飘散,形成花粉浓度晚高峰。(3)相对于软质地面来讲,硬质地表对空气中花粉飘散的影响作用持续时间更长,这也在一定程度上延长了致敏花粉的危害时间,加剧了致敏花粉的污染程度。研究还进一步在花粉致敏树种栽植、地表覆盖方式等方面进行了讨论;同时建议花粉症患者根据花粉污染发生规律合理规避花粉浓度聚集高峰期出行,从而有效缓解致敏花粉对易感人群的健康威胁。     

<Emphasis Type="BoldItalic">Betula</Emphasis> spp. pollen in the atmosphere of Novi Sad (2000–2002)

Pollen of Betula spp. is one of the main European aeroallergens. The aim of this study was to determine characteristics and occurrence of the Betula pollen in Novi Sad atmosphere, based on 3-year observations (2000–2002), and to compare pollen season start dates calculated by different methods. Pollen samples have been collected by Hirst volumetric method with a 7-day Burkard spore trap. Four methods (Sum 75, 2.5%, 30 and 1 pg/m ³) have been used for determination of the start dates of the Betula pollen season and the results have been compared. The total annual pollen sum increased during the observed period. In 2000, 2001 and 2002, the highest daily pollen concentrations were 97, 137 and 1034 pg/m ³, respectively. The earliest Betula pollen season start has been calculated by the 1 pg/m ³ method.     

Floral trait variation in fourCyclamen (Primulaceae) species

The purpose of this study is to examine floral trait variation between fourCyclamen species that show variation in their ability to reproduce in the absence of pollinators and in levels of inbreeding. Pollen and ovule production, pollen/ovule ratio, pollen volume, petal length and width, diameter of the corolla mouth, pistil and stamen length, and stigma-anther separation varied significantly between the four study species. Flower, pollen and ovule production, pollen volume and corolla size were generally highest inC. hederifolium, the species with the lowest level of inbreeding (mean F_is = 0.329), intermediate in both species with relatively high levels of pollinator-mediated inbreeding,C. repandum (mean F_is = 0.658) andC. creticum (mean F_is = 0.748), and lowest in the highly inbredC. balearicum (mean F_is = 0.930). The two species with the most different inbreeding coefficients,C. hederifolium andC. balearicum, had lower pollen-ovule ratios and shorter longevities of stigma receptivity and pollen viability thanC. creticum andC. repandum. These patterns of variation in floral traits are discussed in relation to the relatedness, pollination ecology and levels of inbreeding of the four species.     

外来入侵植物意大利苍耳的传粉生态学特性

从开花物候、花粉活力、柱头可受性、传粉媒介、花粉散布距离、雄性、雌性功能以及繁育系统等方面系统地研究了意大利苍耳的传粉生态学特性,旨在为揭示该物种成功入侵的机理提供科学依据。研究结果显示:意大利苍耳种群的花期较长,雌花花期可达40d,雄花花期可达30d。其雄性和雌性功能都很强,意大利苍耳单株雄花序和花粉量分别高达3847个/株和37903037粒/株,单株雌花序和单株胚珠数高达3847个/株和7694枚/株,种群平均结实率高达80.59%,即平均每株个体能形成6200枚成熟的果实。花粉活力的日变化呈单峰型曲线,早晨和傍晚的花粉活力最低,14:00时的活力高达99%。雌蕊柱头一经伸出总苞即具有可受性,可受期长达7d,开花后的3—4d柱头的可受性最强。意大利苍耳为风媒传粉植物,在4.5km/h的微风条件下,其花粉的散布距离可达45m,大量的花粉集中分布在距花粉源0—20m的范围内,这对于往往高密度连片分布的意大利苍耳种群来说无疑是一种高效的传粉策略。意大利苍耳的交配系统灵活多样,盛花期自然结实率达到100%,套袋试验结果表明该植物自交亲和,自株自然授粉的结实率高达93%。表明较长的花期、大量的雌雄花序及花粉数量、较高的花粉活力、较长的柱头可授期、较远的花粉风媒散布距离、混合交配系统、以及较高的结实率是意大利苍耳繁殖成功的重要保障,也是其成功入侵的重要原因。     

Effects of Nutrient Level on Maternal Choice and Siring Success in <Emphasis Type="Italic">Cucumis sativus</Emphasis> (Cucurbitaceae)

Plants have evolved many mechanisms to increase the chance of gene dispersal mainly through pollen and environmental factors play an important role. Understanding the mechanism behind gene dispersal is therefore crucial in the correct evaluation of the use of genetically modified crops for cultivation. In this paper we address the question of weather nutrient availability for the female affects the outcome of pollen competition between two pollen donor cultivars of Cucumis sativus. We do this by carrying out controlled crosses of female plants grown at three different nutrient levels. We separated the effect of a specific donor from the effect of pollen tube growth rate by using reversed crosses of fast and slow pollen. Our results show that female effects on siring ability vary with nutrient level. Pollen with a high pollen tube growth rate was more successful when nutrient availability for the female was high. This could be the result of selection on the female to adjust preference according to environmental circumstances. Pollen tube growth rate was measured under nutrient rich circumstances, thus high performers possessed traits adapted to a nutrient rich situation. Due to trade-off effects, these traits might not be advantageous in poor environments. Instead, individuals adapted to low nutrient circumstances will have a higher pollen tube growth rate. If siring ability varies with the environment of the recipient plant, this means that assessments of gene flow must account for this variation and include both pollen donors and recipient plants subjected to a range of environmental circumstances. In risk assessments of transgenic plants, plants are often kept under experimental, homogenous conditions. If our results also apply to other species, estimates of gene flow under constant conditions may be misleading. Selection on siring ability and female preference have fundamental effects on gene flow and need to be considered in risk assessments of transgenic plants.Co-ordinating editor: I. Olivieri     

Airborne birch pollen in Neuchâtel (Switzerland): onset, peak and daily patterns

An accurate forecast of the starting point of thebirch pollen season in Neuchâtel can be made byadding the positive daily average air temperature fromFebruary 1st onward until the figure 270 is reached.At this point, the birch trees are ready to bloom.After that, the daily average temperature has toexceed 10 °C to allow pollen release.Today, the birch pollen season starts some 19 daysearlier in the year than in the 1980's, a consequenceof a recent climate change.The daily patterns of airborne birch pollen isirregular. Moreover, pollen concentrations frequentlyexceed the threshold of the appearance of allergicsymptoms, except during rainfall. Therefore, the onlybehavioral recommendation that can be given to peopleallergic to birch pollen is to shorten as much aspossible the contact with outdoor air during the mainbirch pollen season.     

Effects of pollen donors on seed formation inEspeletia schultzii (Compositae) populations at different altitudes

The influence of different pollen donors on seed formation was investigated in three populations ofEspeletia schultzii that differ in environmental conditions and life history characteristics. Self pollen and pollen from different donors (< 15m apart) within each population was used in a diallel design in order to test the genetic base of seed set variation. Three measures of seed formation were used: (1) achene number; (2) proportion of filled achenes (fruits) that distinguishes between achenes with seeds and empty achenes; (3) proportion of aborted seeds that distinguishes between viable and aborted seeds. Self-pollinations resulted in empty achenes. Achene number did not vary between the different pollen donors. A bimodal pattern of filled achenes was found in two populations in two consecutive years. On the other hand, a unimodal pattern was found in crosses between more distant donors (> 30m). These patterns seems to be the results of a sporophytic incompatibility system. Seed abortion was highest at the higher elevations and seems to be correlated with elevation rather than with any genetic effect.