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Among the angiosperms, features of pollen morphology such as grain size, aperture number and surface ornamentation display striking variation. It is less well appreciated that pollen morphology may vary within and among population...
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Among the angiosperms, features of pollen morphology such as grain size, aperture number and surface ornamentation display striking variation. It is less well appreciated that pollen morphology may vary within and among populations of the same species as well as within individual plants. In some species, individual plants produce multiple types of fertile pollen grains (called pollen heteromorphism). Aspects of pollen morphology, such as aperture number, are likely to affect fertilization success with different morphologies favored in different local competitive and ecological environments. This study surveys variation in pollen grain morphology among species throughout the genus Thalictrum. Pollen from individuals of 36 species was rehydrated from herbarium specimens, and light microscopy was used to quantify pollen grain aperture number and size. I find that pollen aperture-number heteromorphism is present within all Thalictrum species studied, and distributions of aperture-number morphs vary both within and among species. This study provides an example of significant pollen heteromorphism within a genus that also varies widely for pollination mode and sexual system.
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? 2022 SAABIntroduction: Triticum aestivum is a self-pollinated species with a high proportion of cleistogamous flowers constituting a blockade for out-crossing. Therefore, male parent characteristics are the main goal in the prod...
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? 2022 SAABIntroduction: Triticum aestivum is a self-pollinated species with a high proportion of cleistogamous flowers constituting a blockade for out-crossing. Therefore, male parent characteristics are the main goal in the production of hybrid wheat seeds. Methods: In a two-year study conducted in Lublin (Poland), the features of flowering biology that can be relevant for the cross-pollination ability of the pollen donor were investigated in winter wheat genotypes. In particular, the anther extrusion capacity, pollen production at the anther and spike levels, and pollen biological value were examined. The pollen production in the anthers was established using an electronic particle counter. The pollen biological value was assessed based on viability (acetocarmine staining) and in vitro pollen germination (raffinose medium) assays. Results: The inter-genotype effect for anther extrusion was significantly correlated to the post-anthesis filament length. The anther extrusion for the individual genotypes fluctuated significantly between the years of the study; however, the interaction with meteorological factors was not assessed. The considerable inter-genotype variability in the pollen donor capability for cross-pollination was highly significantly correlated with the proportion of extruded anthers rather than pollen production, indicating that anther extrusion plays a more important role in the contribution to the final amount of pollen available for cross pollination. The pollen viability determined by staining was high (between 97.5% and 100%), while the in vitro pollen germination varied substantially among the genotypes (between 17.3% and 87.8%). Conclusion: The pollen dispersal ability for cross-pollination in wheat can be improved mainly by increasing the proportion of extruded anthers; however, the pollen production and pollen germination potential cannot be ignored if complete characterization of the ideal male idiotype is to be achieved.
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A uniformidade dos gr?os de pólen de Poaceae aliada aos poucos dados sobre a morfologia polínica no sul do Brasil ocasionam baixa resolu??o taxon?mica em registros polínicos. Neste estudo, foram realizadas análises em gr?os de...
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A uniformidade dos gr?os de pólen de Poaceae aliada aos poucos dados sobre a morfologia polínica no sul do Brasil ocasionam baixa resolu??o taxon?mica em registros polínicos. Neste estudo, foram realizadas análises em gr?os de pólen de espécies campestres de Poaceae de diferentes regi?es do Sul do Brasil, e apresenta-se a diversidade polínica de 70 espécies (59 gêneros, 15 tribos e 6 subfamílias) dos biomas Pampa e Mata Atlantica. As análises morfométricas dos gr?os de pólen indicaram que espécies de campos úmidos apresentaram tamanho maior que os de espécies de campos secos. Apesar das médias das medidas apresentarem pequenas diferen?as entre os tamanhos dos gr?os de pólen dos biomas, esses dados n?o podem ser aplicados aos registros fósseis, uma vez que diferen?as n?o significativas ocorreram entre as amostras, as quais também foram verificadas no tamanho de pólen de espécies C3 e C4, devido à alta varia??o do tamanho dos gr?os de pólen de espécies C3. Esses registros fornecem relevantes inferências ecológicas de gr?os de pólen de Poaceae para a aplica??o em reconstru??es da vegeta??o. Além disso, quanto às rela??es taxon?micas, os resultados sugerem a tendência de diminui??o no tamanho do gr?o de pólen nas tribos mais derivadas. Palavras-chave: registros polínicos, Palinologia, bioma Pampa, gramíneas, gr?os de pólen diporados.
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Pollen descriptions of Echinopepon species and a palynological key are presented. Data on apertures, exine, polarity, shape, and size of pollen grains are included. Pollen morphology is distinctive for the species of Echinopepon a...
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Pollen descriptions of Echinopepon species and a palynological key are presented. Data on apertures, exine, polarity, shape, and size of pollen grains are included. Pollen morphology is distinctive for the species of Echinopepon and Echinocystis and in some Marah species. The main features of each taxon are illustrated by photographs.
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Self- and cross-compatibility, and the pollen-related characteristics of 18 apricot cultivars were evaluated at National Horticultural Research Institute, Suwon for three blooming seasons from 2000 to 2002. Although the number of ...
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Self- and cross-compatibility, and the pollen-related characteristics of 18 apricot cultivars were evaluated at National Horticultural Research Institute, Suwon for three blooming seasons from 2000 to 2002. Although the number of normal pollen grainsper flower ranged from 5.75 × 10~4 in 'Choha' to 8.37 × 10~3 in 'Heiwa', the numbers did not show any clear differences according to ecological group of apricot. Abnormal pollen grains per flower ranging from 2.30×10 in 'Goldrich' to 2.70×10 in 'Goldcot' were frequently observed in all cultivars. The percentage of pollen germination was high in 'Goldcot', 'Royal', 'Tirynthos', 'World Peach' more than 10%, while low in 'NY 458' and 'Yamagata No. 3' less than 1%. Many cultivars excepting 'Choha', 'Early Orange', 'Hiroshimaoomi', 'Ivonne Liverani', 'Royal', and 'Tirynthos' showed low self-compatibility, less than 5% in the percentage of fruit set. Therefore, co-planting with pollinizer cultivars was recommended for the stable fruit set. Seven major orpromising cultivars under Korean climatic condition showed enough cross-compatibility with 9 cultivars, over than 20% as the percentage of fruit set. However, low percentage of fruit set in the combination 'Choha' x 'Chinese', 'Harcot' x 'Chinese' was observed and therefore the further evaluation will be required.
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In apomictic pseudogamous reproduction, the asexual embryo requires a sexual origin of the endosperm for its nutrition; hence, fertilization is necessary for seed development to occur. Male gametophyte functionality in apomictic p...
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In apomictic pseudogamous reproduction, the asexual embryo requires a sexual origin of the endosperm for its nutrition; hence, fertilization is necessary for seed development to occur. Male gametophyte functionality in apomictic polyploids is highly variable and often linked to low values of pollen grain viability. This work evaluates pollen grain development and functional attributes in Psidium cattleyanum, a polyploid and apomictic pseudogamic species. We consider pollen grain ontogeny and pollen grain morphology, size, and viability in two ploidy levels, octoploid and heptaploid. Plants with different ploidy levels showed variation in the duration of microsporogenesis and the size of microspores. Microsporogenesis exhibited several abnormalities in all studied plants, but more frequently in heptaploids; cytomixis was detected in meiosis. Psidium cattleyanum pollen grains registered morphotypes typical of the Myrtaceae family and other heteropolar forms that were not previously described for the genus. Pollen grain size was heterogeneous but larger in octoploid plants. Pollen viability was low and varied both intra- and between ploidies; pollen morphotypes contribute differently to pollen viability depending on the ploidy of the plant. Several abnormalities detected during pollen grain ontogeny affect pollen grains performance. Polyploidy is proposed as the leading cause of meiosis abnormalities. Further, variations in pollen grain viability and final pollen size and morphology found in different plants suggest that ploidy levels can affect these attributes differently.
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The pollen morphology, viability, germination and pollen tube growth of six wide-spread plum genotypes (Prunus domestica), were studied. 'Toptaste', 'Topfive' and 'Gras ameliorat' had the largest pollen grains (> 50 um), whereas '...
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The pollen morphology, viability, germination and pollen tube growth of six wide-spread plum genotypes (Prunus domestica), were studied. 'Toptaste', 'Topfive' and 'Gras ameliorat' had the largest pollen grains (> 50 um), whereas 'Jojo', 'Anna Spath' and 'Stanley' cultivars were represented by slightly smaller pollen size (45.28 -48.41 um). Pollen shape was prolate-sheroidal (L/W ratio 1.18-1.02 um) in the polar view and spherical-triangular in the equatorial view. Pollen viability varied with the genotype: the highest percentage was observed for 'Jojo' (40.96%) and 'Toptaste' (40.87%), the lowest was recorded for 'Gras ameliorat' (26.33%). The highest pollen germination (87.0%) at the end of 24 h incubation at 10°C was recorded for 'Stanley'. 'AnnaSpath' developed the longest pollen tubes (1061.1 um) when the pollen grains were incubated at 15°C for 24 h.
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The related factors concern the dates of the appearance of pollen grains in the air, the duration of the presence of sporomorphs and the maximum concentrations in particular seasons were investigated. The aim of the study was to c...
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The related factors concern the dates of the appearance of pollen grains in the air, the duration of the presence of sporomorphs and the maximum concentrations in particular seasons were investigated. The aim of the study was to compare the airborne concentrations of allergenic pollen produced by three dominant early flowering tree taxa (Cupressus, Pinus and Olea) in the three different sites (Ajlun city (A), Rabbad castle (C), and Debbeen (D)) of Ajlun during the years 2006-2007. Measurements were performed by the volumetric method. Pollen seasons were defined as the periods in which 95% of the total catch occurred. Significant differences in the pollen count of the examined taxa were observed between two seasons: the pollen count of Cupressus washigher in 2006 than in 2007, while for Pinus and Olea the opposite was the case. Tire highest concentration and annual pollen counts of Pinus, Cupressus and Olea were measured in Ajlun city in both seasons, where the annual pollen count of Olea in 2007 was four times higher than in 2006 and equalled 4,215 grains in m~3 per 24 h. The longest pollen seasons were observed at low annual pollen counts for the pollen of Cupressus. Results of the study reveal significant differences between the seasons and thecities. The pollen counts of Cupressus, Pinus and Olea trees are determined by the weather, diversity of local flora and specific rhythm of pollination of particular taxa.
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The airborne pollen grains of Afyon have been studied for a two-year period (1999-2000) with a Durham sampler. A total of 14367 pollen grains belonging to 40 taxa have been identified and recorded with some unidentified ones. Of t...
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The airborne pollen grains of Afyon have been studied for a two-year period (1999-2000) with a Durham sampler. A total of 14367 pollen grains belonging to 40 taxa have been identified and recorded with some unidentified ones. Of them, 6732 were identified in 1999 and 7635 in 2000. Of the total pollen grains, 69.67% were arboreal, 26.64% non-arboreal and 3.68% unidentified. The majority of the investigated pollen grains were from Pinus, Gramineae, Cupressaceae, Platanus, Chenopodiaceae/Amaranthaceae, Quercus, Ailanthus, Moraceae, Juglans, Salix, Cedrus and Rosaceae. The highest level of pollen grains was in May.
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Air sampling was carried out during February 1992 to January 1994 by operating modified Durham's air sampler at three different sites at a height of 6 m from the ground. Altogether, 57 types of pollen belonging to 32 families were...
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Air sampling was carried out during February 1992 to January 1994 by operating modified Durham's air sampler at three different sites at a height of 6 m from the ground. Altogether, 57 types of pollen belonging to 32 families were observed. Asteraceaefollowed by Ulmaceae contributed maximum number of pollen in the air whereas Caricaceae, Cannaceae and Punicaceae the least. Pollen grains of tree species were encountered more as compared to herbs and shrubs. The calendar revealed two peak periods of pollen incidence i.e. (i) January - April and (ii) August - November. Pollen incidence synchronised with the flowering period of the local plant species. Also, the pollen types belonging to anemophilous were trapped in high numbers than entomophilous plant group.
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