Search results for "Pollen"
showing 10 items of 302 documents
Hybridization and competition between the endangered sea marigold (Calendula maritima, Asteraceae) and a more common congener
2013
Occurrences of hybridization between the rare, endangered Sicilian endemic, Calendula maritima, and other congeners in the wild have been suspected by several authors, but never demonstrated. In San Cusumano (Trapani), one of the only three Sicilian mainland populations, C. maritima occurs in close proximity to the more common congener C. suffruticosa subsp. fulgida, and individuals morphologically intermediate between the two taxa have been observed. In order to determine whether hybridization is occurring at this site, and, if so, begin to assess the impact it could have on C. maritima, two independent tests of hybridity were conducted by studying (1) the pollen morphology and viability a…
SELFING ABILITY AND MALE STERILITY IN SENECIO VERNALIS WALDST. ET KIT. (ASTERACEAE) FROM ISRAEL
1994
Two major findings relating to the breeding system of Senecio vernalis from Israel are reported. First, isolation experiments failed to confirm the existence of a widespread, truly self-compatible and predominantly self-pollinating breeding system in Israeli populations of S. vernalis. However, a single S. vernalis plant derived from a natural stand at Jerusalem was found to be self- compatible and strongly self-pollinating. In its progeny, there were signs of inbreeding depression commonly associated with selfed offspring of outbreeding species. Selfing ability ratios in this progeny indicate a single dominant gene for selfing ability in S. vernalis. The implications of these observations …
Methods of the investigation of bee pollen and bee bread
2017
The main purpose of this publication was to evaluate which types of studies are used with the purpose of the estimation of nutritional value of bee pollen and bee bread. Bee pollen and bee bread are important bee-products that contains large amounts of nutritional and essential active biological compounds. Among different bioactive compounds with antioxidant properties which could be found in bee pollen and bread are polyphenolic substances, flavonoids, unsaturated acids and carotenoids. Bee pollen and bee bread are investigated by plenty of scientists for different quality indexes over two last decades. However, the composition of bee pollen and bee bread are not yet standardized nor defin…
Floral Diversity and Pollen Transfer Mechanisms in Bird-pollinated Salvia Species
2007
† Background and Aims Bird-pollinated (ornithophilous) Salvia species (sages) transfer pollen either by means of a staminal lever mechanism or by immovable stamens. As the distribution of the two modes within the genus is not known, we present a survey of all ornithophilous sages. The main focus is given to floral diversity especially with respect to functional lever morphology. Thereby the hypothesis is tested that, due to a pollinator shift from bees to birds, the lever mechanism became unnecessary. † Methods To get a general idea about the diversity of pollen transfer mechanisms, 186 ornithophilous Salvia species were classified according to the functional morphology of the stamen and th…
Presence of esterase inPinaceae pollen
1997
General esterases, like wall heterologous enzymes, may be implicated in allergenic mechanisms. We cytochemically examined the presence of these enzymes, bearing in mind thatPinus spp. is often considered a possible cause of allergies. Positive esterase results in fungus spores were found on the strip of a volumetric sampler. Data are reported here, together with the hypothesis of a possible esterase-allergenic link regarding fungus spores.
The Influence of Brassinosteroid, a Growth-promoting Steroidal Lactone, on Development and CO2-fixation Capacity of Intact Wheat and Mustard Seedlings
1984
In 1970, Mitchell et al. isolated a lipoidal complex from the pollen of rape (Brassica napus L.). This complex, called “Brassins” was found to have partly powerful growth-promoting properties. The novel growth response of young bean plants in the second internode assay (Worley, Mitchell 1971; Mitchell, Gregory 1972) and other physiological changes following Brassin-treatment have been studied under several aspects (Krizek, Worley 1981; Gregory 1981).
Non-hydrolysable macromolecular constituents from outer walls of Chlorella fusca and Nanochlorum eucaryotum
1992
Abstract Many green microalgae possess a thin trilaminar outer wall (TLS) with a very high resistance to chemical degradation. TLS are known to play an important protective role in living cells. They are also selectively preserved during fossilization and thus provide a major contribution to the fossil organic matter of a number of sedimentary rocks. However, little information is available on TLS chemical structure. Examination of the TLS of Chlorella fusca (a lacustrine Chlorophycea) and of Nanochlorum eucaryotum (a recently discovered marine Chlorophycea) indicated that (i) they exhibit morphological features commonly observed in other green microalgae, (ii) their non-hydrolysable macrom…
Changes of effective gene dispersal distances by pollen and seeds across successive life stages in a tropical tree
2013
Pollen and seed dispersal are the two key processes in which plant genes move in space, mostly mediated by animal dispersal vectors in tropical forests. Due to the movement patterns of pollinators and seed dispersers and subsequent complex spatial patterns in the mortality of offspring, we have little knowledge of how pollinators and seed dispersers affect effective gene dispersal distances across successive recruitment stages. Using six highly polymorphic microsatellite loci and parentage analyses, we quantified pollen dispersal, seed dispersal, and effective paternal and maternal gene dispersal distances from pollen- and seed-donors to offspring across four recruitment stages within a pop…
Effects of defoliation on male and female reproductive traits of a perennial orchid, Dactylorhiza maculata
2000
1The effects of defoliation on male reproductive traits of plants have received little attention. We conducted two field experiments with Dactylorhiza maculata (L.) Soo to examine the effects of defoliation on both male and female reproductive traits. We removed 0, 50 or 100% of leaves prior to flowering. The quality of pollen was tested by transferring pollen from the differently treated plants to untreated plants of the same population. 2The non-defoliated plants did not differ from the defoliated plants in mass of pollinia. No differences were found in the weight of seed capsules or in the proportion of embryonic seeds raised by flowers receiving pollen from differently treated pollen do…
Pollination: An Integrating Factor of Biocenoses
1991
A survey is given of the ecological constraints which affect the process of pollen transfer — and hence the gene flow — within a biocenosis. Wind pollination (anemophily) plays a dominant role in species-poor communities only. The quantity of zoophilous species increases equator-ward to up to 100 % and so does the degree of integration in animal-plant interactions. Biotic pollination is pinpointed. Manifoldness and specifity of methods reduce pollen waste and mispollinations. Saturated ecosystems dispose of a complete set of pollination syndromes and the respective pollinator guilds, narrow niche widths, a high percentage of eutropic flowers, shorter flowering times, and a temporal and spat…