Search results for "botany"
showing 10 items of 4586 documents
Galerucella nymphaeae (Col., Chrysomelidae) grazing increases Nuphar leaf production and affects carbon and nitrogen dynamics in ponds.
1990
The grazing effects of the waterlily beetle Galerucella nymphaeae on Nuphar lutea stands were studied in three ponds in Central Finland. Production of floating leaves of N. lutea and growth in the G. nymphaeae population were investigated in the ponds and bioenergetics of the beetle larvae in the laboratory. Combination of field and laboratory data enabled estimation of the effect of the beetle on the production of floating leaves of N. lutea and the consequences of grazing for the input of detritus from Nuphar into the ponds. Adults and larvae of G. nymphaeae consumed 3.0–6.1% of the net annual floating leaf production during the growing period. In addition to consumption losses, feeding a…
Hieracium barrelieri, a new hawkweed species from S Italy, with notes on Tenore’s Hieracium murorum var. barrelieri (Asteraceae)
2015
A new species from Montevergine in Campania, Hieracium barrelieri, is described in detail. It is closest to H. acanthodontoides of H. sect. Acanthodontoidea. H. murorum var. barrelieri, an obsolete taxon described by Tenore, is also discussed, as it was partly based on the same population.
The inheritance of organogenic response in melon
1996
Previous studies have demonstrated variation in organogenic competence among plants within a population ofCucumis melo. In order to determine if leaf explant response is under genetic control, we investigated the distribution of the shoot regeneration frequency in F1 and F2 generations from parents representing extreme values forin vitro organogenic response. Results suggest a genetic model with two genes, partial dominance, independent segregation and similar effects for both genes.
Influence of the storage conditions on some physicochemical and mycological parameters of honey
1994
The authors studied the changes in yeast and mould counts, pH, free and lactone acidity, colour and sugar composition undergone by honeys with water contents of 169, 188 and 220 g kg-1 on storage at refrigeration temperature (4–7°C), room temperature and 28°C for two years. Of the solid culture media assayed, honey agar and osmophilic medium fostered yeast growth while malt-extract agar and yeast-extract-malt-extract agar allowed for better development of filamentous fungi. The yeasts isolated belonged to the genera Saccharomyces, Schizosaccharomyces and Zygosaccharomyces, while filamentous moulds were of the genera Aspergillus, Penicillium, Fusarium and Alternaria. The honeys studied under…
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…
Reproductive success ofDactylorhiza incarnatassp.incarnata(Orchidaceae): the effects of population size and plant visibility
2007
Reproduction of plants pollinated solely by flower-visiting animals depends on the ability of the population and each of its flowering member to attract pollinators. Factors affecting the pollination of nectarless species differ somewhat from those affecting the pollination of rewarding species due to the avoidance behaviour of pollinators after visiting empty flowers. We studied a non-mimic food-deceptive orchid, Dactylorhiza incarnata ssp. incarnata, in 16 populations in central Finland to examine if population properties and plant size affected reproductive success of plants. We found that the number of flowering plants increased total pollinia removal and seed production of the populati…
RAPD evidence for a sister group relationship of the presumed progenitor-derivative species pairSenecio nebrodensis andS. viscosus (Asteraceae)
1998
The phylogenetic and phenetic analysis of 109 RAPD polymorphisms inS. nebrodensis, a perennial and self-incompatible endemic of four mountain ranges in Spain, andS. viscosus, a self-compatible annual widespread in Europe, as well asS. lividus, S. sylvaticus andS. vulgaris revealed a sister group relationship between the first two species. This result contrasts sharply with the earlier hypothesis based on isozyme variation thatS. viscosus originated from within a paraphyleticS. nebrodensis and that the two species represent a progenitor-derivative pair. After considering possible reasons for the sister group relationship found, including the possibility of rooting artefacts, it is concluded …
The phylogeny and biogeography of Gentiana L. sect. Ciminalis (Adans.) Dumort.: A historical interpretation of distribution ranges in the European hi…
1998
Abstract Gentiana sect. Ciminalis consists of seven mostly ecologically or geographically vicariant and closely related species which are distributed throughout the South and Central European high mountains. The analysis of a RAPD data set and trn L-intron and ITS sequences resulted in slightly different phylogenetic hypotheses. In the preferred hypothesis the group consists of two completely resolved main lineages: 1) G. clusii and G. alpina. 2) G. dinarica, G. acaulis, G. ligustica, G. angustifolia and G. occidentalis. The most important conclusions we have drawn from this phylogenetic hypothesis and from the observed patterns of molecular variation are: 1) The calcifuge ecology of G. aca…
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…
Characterization and classification of different genotypes in a population of Cucumis melo based on their ability to regenerate shoots from leaf expl…
1995
Variability of the in vitro organogenic response from leaf explants of a seed population of Cueumis melo L. ev. Cantaloupe Charentais was analyzed to detect genotypic variability among individual seeds for shoot regeneration. Variation in shoot regeneration frequency among plants from different seeds was compared to that found among clonal replicas of each original plant. Clonal propagation was performed using in vitro culture of apical and axillary buds of axenic plants to avoid somaclonal variation. Results demonstrate the existence of highly significant differences among plants from the seed population. Regeneration frequency of leaf explants derived from clonally propagated sets of a si…