摘要:

Pollen morphological studies have been carried out by SEM on 23 species ofSorghum(Gramineae) in order to resolve the exine surface patterns in sectionsEu-sorghum(subsectionArundinacea-seriesSpontaneaandSativaand subsectionHalepensia), andPara-sorghum. Basically, two exine ornamentation types have been observed viz. granular and insular. In sectionEu-sorghum, seriesSpontaneaandSativa(of subsectionArundinacea) are heterogeneous having both types of exine pattern. In the same section, subsectionHalepensiais characterised by having only a granular exine. SectionPara-sorghumshows a marked pollen morphological similarity with subsectionHalepensiaof sectionEu-sorghum. Snowden's concept that the two seriesSpontaneaandSativaare closely related and that the cultivatedSorghum(seriesSativa) might have evolved from the wildSorghum(seriesSpontanea), is supported by the present observations.

ISSN:0017-3134    

DOI:10.1080/00173139409428987

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A particular pollen type is observed in the speciesEuphorbia caputmedusaewhich is distributed in South Africa. The exine of this pollen is clearly rugulose and beset with coarse granules. In addition 10 to 25% of the pollen grains are heteropolar and have a characteristic aperture type which is something between tricolporate and parasyncolpate. The pollen morphology of this species gives grounds for suggesting its removal from the sectionEuphorbiumto a separate section, as suggested by Carter (1988).

ISSN:0017-3134    

DOI:10.1080/00173139409428988

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Honey bees,Apis mellifera, forage readily on flowers of upland cotton,Gossypium hirsutum, to harvest nectar. The abundant pollen gets caught in the haircoat of the bees, but cotton pollen is nevertheless rarely collected. Honey bee pollen collection effectiveness was therefore investigated in a flight room using cotton and five other spheroidal pollen taxa presented in sequence. Honey bees visited all pollen dishes, but okra pollen (Abelmoschus esculentus) was never packed successfully by the bees landing in the pollen dish. Cotton pollen was collected by 16% of the landing foragers, pumpkin pollen (Cucurbita pepo) by 71%, and pollen of corn (Zea mays), pigweed (Amaranthus palmeri), and sunflower (Helianthus annuus) were readily collected by nearly all foragers. The amount of time spent in the pollen dish was always short (1 to 9 seconds) and homogeneous among all pollen taxa, indicating that none of them was strongly repellent to the bees. The reduced effectiveness with which honey bees collected cotton pollen was demonstrated by the longer amount of time needed for pollen grooming and packing between two consecutive landings in the pollen dish and the small size of cotton pollen pellets (averages of 0.42 mg and 8.23 mg per pellet for cotton and corn pollen, respectively). This reduced efficiency in cotton pollen collection was associated primarily with the length of the spines on cotton pollen which physically interfered with the pollen aggregating process used by honey bees.

ISSN:0017-3134    

DOI:10.1080/00173139409428989

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The Maastrichtian chalks of Denmark and the Danish North Sea contain a new gonyaulacoid dinoflagellate cyst,Glaphyrosphaera glabragen. et sp. nov. The new genus is holocavate and laterally compressed with precingular archeopyle, type P (3″) and is unique in having a funnelshaped process which connects the peri-and endophragm in the sulcal areas. The new genus is currently monotypic and restricted to the Maastrichtian Stage.

ISSN:0017-3134    

DOI:10.1080/00173139409428990

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Pollen grains of 10 anemophilous and entomophilous species of angiosperms were kept at 4 relative humidities (RH) (15, 51, 79 and 98%) and their viability tested by fluorochromatic reaction after time lapses ranging from 6 to 144 h. Pollen viability in the anemophilous species decreased more rapidly than in the entomophilous ones with the exception of the dioecious palmChamaerops humilis. The modes of anther and flower opening, times of anther exposure etc. were recorded: Cytological data are discussed and compared with these aspects of reproductive ecology.

ISSN:0017-3134    

DOI:10.1080/00173139409428991

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The occurrence of airborne Scots pine pollen was continuously monitored with Burkard traps at five locations situated along a 1000 kilometre transect in Finland during the ten-year period 1982–1991. The variation between years in airborne pollen dispersal was significant. The pollen season (defined as 10% of the cumulative pollen count for the year) began in South Finland, on average, on June 1st, and in North Finland 24 days later. The length of the mean local pollen season was 11 days, increasing towards the north. On average over 21% of the total pollen count of the year was caught on one single day. The temperature sums (d.d. >+5°C) required for the start of the pollen season decreased almost linearly from 193 d.d. in the south to 132 d.d. in the north. However, in several years the pollen seasons overlapped between sites at a distance of 500 km or more. The temperature sum on June 1st explained over 80% of the variation in the onset, median and end of the pollen season in Finland.

ISSN:0017-3134    

DOI:10.1080/00173139409428992

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Atmospheric pollen was collected with a Burkard spore trap in Ankara, Turkey, from January 1990 to January 1993. A total of 135.787 grains/m3belonging to 47 taxa were observed. The local pollen season started in February in 1990 and 1991 and in March in 1992. Relatively low pollen concentrations were recorded in 1990 and 1992, probably because of precipitation and low wind speed in the spring. A relatively high pollen concentration was recorded in 1991 which could be caused by higher wind speed in the spring and more precipitation during the winter. Cupressaceae/Taxaceae, Pinaceae, Gramineae,Betula, Moraceae,Platanus, Populus, Acer, Quercus, Chenopodiaceae/Amaranthaceae,Plantago, Rumexare found to be the dominant pollen types in the atmosphere in Ankara. The pollen composition generally reflects the vegetation of gardens, parks and roadsides, while the natural steppe vegetation of the area around Ankara is not properly represented.

ISSN:0017-3134    

DOI:10.1080/00173139409428993

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The conidia ofColletotrichum gloeosporioideswere found to be dispersed during rainfall by wash-off and splash mechanisms. The initiation and development of onion anthracnose was found to depend on the frequency of rainfall and the movement of conidial inoculum during rainfall. Experiments conducted under controlled conditions in the laboratory employing splash and wash-off assemblies showed that impacting incident water drops (splash) and flowing water (wash-off) liberated the conidia from the anthracnose lesions of the onion leaf/peduncle. Peak liberation of conidia occurred with 3 to 5 water drops and most of the conidia were removed from the source within 90 seconds. A possibility of the dispersal of conidia ofC. gloeosporioidesfrom soil to lower leaf by splash mechanisms and then from the leaves to the neck of the onion bulb and to the bulb by wash-off mechanisms is indicated.

ISSN:0017-3134    

DOI:10.1080/00173139409428994

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Outdoor air-sampling surveys were conducted in February, May, August and December 1992 with a Samplair-MK1 particle sampler at 50 randomly chosen sites in the Kitchener-Waterloo area of southern Ontario, Canada. Canonical Correspondence Analysis of the resulting data revealed that the influence of some environmental factors on the airborne fungal spora varied with the season of the year. Among the 16 environmental factors measured at each sampling time, the most important were found to be: relative humidity, rain, vegetation, cloud, temperature, and wind speed, in descending order. The composition of the airborne fungal spora also changed with the season. The dominantCladosporium, AlternariaandAspergillus + Penicilliumwere found at all seasons, butGanoderma, Leptosphaeria, Coprinus, and Polythrinciumoccurred mainly in summer. Positive relations were revealed between, on the one hand, (1a) relative humidity, (1b) rain, (1c) cloud and (1d) temperature, and on the other hand, (2) high spore counts ofLeptosphaeria, Xylariaceae, unidentified Ascomycetes, andGanoderma. A similar relationship was detected between (1) vegetation and (2)AlternariaandOidium. (1) Higher wind speeds were positively related with (2) hyphal fragments and relatively large spores, such as those ofDrechslera, Nigrospora, Periconia, andOidium. Canonical Correspondence Analysis provides both a new approach to the analysis of aeromycological data and informative graphical presentations of the results.

ISSN:0017-3134    

DOI:10.1080/00173139409428995

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The antigenity of outdoor dust which has settled on surfaces has been a neglected subject in aerobiological and allergological studies, although this dust is undoubtedly one of the main sources of airborne antigenic particles which cause allergic symptoms. Dust samples for birch pollen antigen analyses were taken with a vacuum sampler from horizontal surfaces, and from birch and maple leaves once a week after the peak birch pollination period. The samples were analysed by a modification of the IgG-ELISA-procedure. The antigenicity of dust on all surfaces remained high for months after birch pollination, even on days when no pollen grains were microscopically detected in the dust samples. Outdoor dust being one of the sources of indoor dust is thus a component of the mixture which brings about an allergy to house dust. Dust with a high antigenicity, carried inside from outdoors may be one cause of the occurrence of allergic symptoms outside of the pollen season.

ISSN:0017-3134    

DOI:10.1080/00173139409428996

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor