An allozyme study of sexual and vegetative regeneration in Hieracium pilosella

2007 ◽  
Vol 85 (1) ◽  
pp. 10-15 ◽  
Author(s):  
Hans Henrik Bruun ◽  
J.F. Scheepens ◽  
Torbjörn Tyler
Keyword(s):  
Vegetative Reproduction ◽  
Clonal Diversity ◽  
Clonal Plant ◽  
Field Studies ◽  
Relative Importance ◽  
Biotic And Abiotic Stress ◽  
Hieracium Pilosella ◽  
Vegetative Regeneration ◽  
Mesic Site ◽  
Allozyme Study

Allozyme markers were used to fingerprint clones of the grassland plant Hieracium pilosella L. and, by inference, to estimate the relative importance of sexual and vegetative reproduction in a population. Field studies in populations of clonal plant species have often reported negligible or absent recruitment from seed. In contrast, studies of genetic markers have found substantial clonal diversity in populations, suggesting recruitment of new genets into established populations. Our results showed that H. pilosella regenerates from seed both within and between dense clonal patches. Two sites differing in environmental conditions were sampled to investigate how the balance between seed-derived and stolon-derived recruitment changes with biotic and abiotic stress. In a relatively drought-prone site on a south-facing slope, the balance was shifted towards recruitment from seed, compared with a mesic site in which vegetative regeneration was more important.

Clonal Diversity in Differently-Aged Populations of the Pseudo-Annual Clonal Plant Circaea lutetiana L.

Plant Biology ◽  
2000 ◽  
Vol 2 (6) ◽  
pp. 646-652 ◽  
Author(s):  
R. Verburg ◽  
J. Maas ◽  
H. J. During
Keyword(s):  
Clonal Diversity ◽  
Clonal Plant

scholarly journals Climatic controls on diffuse groundwater recharge across Australia

2012 ◽  
Vol 9 (5) ◽  
pp. 6023-6062 ◽  
Author(s):  
O. V. Barron ◽  
R. S. Crosbie ◽  
D. Pollock ◽  
W. R. Dawes ◽  
S. P. Charles ◽  
...  
Keyword(s):  
Groundwater Recharge ◽  
Vapour Pressure Deficit ◽  
Field Studies ◽  
Annual Rainfall ◽  
Temperate Climate ◽  
Relative Importance ◽  
Climate Type ◽  
Climate Parameters ◽  
Climate Controls ◽  
Temperature Climate

Abstract. Reviews of field studies of groundwater recharge have attempted to investigate how climate characteristics control recharge, but due to a lack of data have not been able to draw any strong conclusions beyond that rainfall is the major determinant. This study has used numerical modeling for a range of Köppen-Geiger climate types (tropical, arid and temperate) to investigate the effect of climate variables on recharge for different soil and vegetation types. For the majority of climate types the total annual rainfall had a weaker correlation with recharge than the rainfall parameters reflecting rainfall intensity. In regions with winter-dominated rainfall, annual recharge under the same annual rainfall, soils and vegetation conditions is greater than in regions with summer-dominated rainfall. The relative importance of climate parameters other than rainfall is higher for recharge under annual vegetation, but overall is highest in the tropical climate type. Solar radiation and vapour pressure deficit show a greater relative importance than mean annual daily mean temperature. Climate parameters have lowest relative importance in the arid climate type (with cold winters) and the temperate climate type. For 75% of all considered cases of soil, vegetation and climate types recharge elasticity varies between 2 and 4, indicating a 20% to 40% change in recharge for a 10% change in annual rainfall Understanding how climate controls recharge under the observed historical climate allows more informed choices of analogue sites if they are to be used for climate change impact assessments.

scholarly journals Changes in the growth and reproduction of a clonal plant as a result of disruption of mycorrhizal network

2021 ◽  
Vol 66 (2) ◽  
pp. 195-200
Author(s):  
Martyna Dominiak-Świgoń ◽  
Zbigniew Kasprzykowski ◽  
Marlena Lembicz
Keyword(s):  
Resource Allocation ◽  
Sexual Reproduction ◽  
Mycorrhizal Fungus ◽  
Clonal Plant ◽  
Limited Resource ◽  
Clonal Plants ◽  
Dry Mass ◽  
Mother Plant ◽  
Hieracium Pilosella ◽  
Mycorrhizal Network

In a clonal network, a mother plant is connected with daughter ramets. During network development, new ramets may encounter barriers that disrupt network integrity. As a result, resource allocation within a network is disturbed. In this study, the effect of network integrity disruption on the size of ramets and their sexual reproduction was investigated in mouse-ear hawkweed (Hieracium pilosella). Three types of networks were formed experimentally with unlimited resource allocation, with limited resource allocation between a mother plant and its daughter ramets and with limited resource allocation between all ramets. Networks were either supported by the presence of a mycorrhizal fungus or restricted by its absence. We found that the size of the mother and the effectiveness of sexual reproduction did not differ among network types. The length and dry mass of runners were higher in cases with limited resource exchange between a mother plant and its daughters. In the clonal plant network without any barriers to connection, a higher number of rosettes and lower dry mass of daughters were recorded. The mean number of daughter flowers did not differ among the network types. Mycorrhizal network is one of the most important factors for the sexual reproduction of clonal plants. With a reduced mycorrhizal network, plants invested in clonal growth.

Field studies on 14C assimilate fixation and movement in oil-seed rape (B. napus)

1984 ◽  
Vol 102 (1) ◽  
pp. 23-31 ◽  
Author(s):  
J. F. Chapman ◽  
R. W. Daniels ◽  
D. H. Scarisbrick
Keyword(s):  
Resource Utilization ◽  
Field Experiments ◽  
Field Studies ◽  
Relative Importance ◽  
Oil Seed ◽  
Oil Seed Rape ◽  
Efficient Resource ◽  
Major Supplier ◽  
College Farm ◽  
Wye College

SummaryThe roles of leaves, stems and reproductive parts in 14CO2 fixation and its subsequent movement in winter oil-seed rape, cultivar Jet Neuf, were investigated in two field experiments carried out on the Wye College Farm. The relative importance of these organs changed with time. At early flowering the leaves were the most important photosynthetic organs (66·8% 14CO2 activity). Midway between flowering and maturity the stems became the major supplier of photosynthates, a role eventually taken over by the developing siliquae (pods).These data stress the importance of keeping all photosynthetically active surfaces free from disease if efficient resource utilization and higher yields are to be achieved.

An analysis of using entomopathogenic nematodes against above-ground pests

2004 ◽  
Vol 94 (4) ◽  
pp. 297-306 ◽  
Author(s):  
S. Arthurs ◽  
K.M. Heinz ◽  
J.R. Prasifka
Keyword(s):  
Treatment Efficacy ◽  
Entomopathogenic Nematodes ◽  
Field Studies ◽  
General Linear Model ◽  
Common Species ◽  
Steinernema Carpocapsae ◽  
Relative Importance ◽  
Ecological Barriers ◽  
Soil Insects ◽  
Wetting Agents

AbstractApplications of entomopathogenic nematodes in the families Steinernematidae and Heterorhabditidae have traditionally been targeted against soil insects. Nonetheless, research over the last two decades highlights the potential of such agents against above-ground pests under certain circumstances. A general linear model was used to test for patterns in efficacy among 136 published trials with Steinernema carpocapsae Weiser, the most common species applied against foliar and other above-ground pests. The focus was on field and greenhouse assessments, rather than laboratory assays where relevant ecological barriers to infection are typically removed. The model showed differences in nematode treatment efficacy depending on the pests’ target habitat (bore holes > cryptic foliage > exposed foliage) and trial location (greenhouse > field studies). Relative humidity and temperature during and up to 8 h post-application were also predicted to influence rates of nematode infection obtained. Conversely, spray adjuvants (both wetting agents and anti-desiccants) and nematode dosage applied (both concentration and use of consecutive applications 3–4 days apart) did not explain a significant amount of variance in nematode performance. With reference to case studies the model is used to discuss the relative importance of different factors on nematode efficacy and highlight priorities for workers considering using entomopathogenic nematodes to target pests in novel environments.

scholarly journals Quality transformation of dissolved organic carbon during water transit through lakes: contrasting controls by photochemical and biological processes

2017 ◽  
Author(s):  
Martin Berggren ◽  
Marcus Klaus ◽  
Balathandayuthabani Panneer Selvam ◽  
Lena Ström ◽  
Hjalmar Laudon ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Heterotrophic Bacteria ◽  
Field Studies ◽  
Boreal Lakes ◽  
Biological Processes ◽  
Relative Importance ◽  
In Situ Data ◽  
Headwater Lakes ◽  
Quality Transformation

Abstract. Dissolved organic carbon (DOC) may be removed, transformed or added during water transit through lakes, resulting in qualitative changes in DOC composition and pigmentation (color). However, the process-based understanding of these changes is incomplete, especially for headwater lakes. We hypothesized that because heterotrophic bacteria preferentially consume non-colored DOC, while photochemical processing remove colored fractions, the overall changes in DOC quality and color (absorbance) upon water passage through a lake depends on the relative importance of these two processes, accordingly. To test this hypothesis we combined laboratory experiments with field studies in nine boreal lakes, assessing both the relative importance of different DOC decay processes (biological or photo-chemical) and the loss of color during water transit time (WTT) through the lakes. We found that photo-chemistry qualitatively dominated the DOC transformation in the epilimnia of relatively clear headwater lakes, resulting in selective losses of colored DOC. However, in highly pigmented brown-water lakes (absorbance at 420 nm > 7 m−1) biological processes dominated, and there was no systematic relationship between color loss and WTT. Instead in situ data and dark experiments supported our hypothesis of selective microbial removal of non-pigmented DOC, mainly of low molecular weight, leading to persistent water color over time in these lakes. Our study shows that individual brown headwater lakes do not conform to the commonly reported pattern of selective removal of colored constituents in freshwaters, but rather the DOC shows a sustained degree of pigmentation upon transit through these lakes.

Modeling cadmium uptake from water and food by the freshwater bivalve Pyganodon grandis

2010 ◽  
Vol 67 (11) ◽  
pp. 1874-1888 ◽  
Author(s):  
Sophie Cooper ◽  
Landis Hare ◽  
Peter G.C. Campbell
Keyword(s):  
Digestive Gland ◽  
Dietary Exposure ◽  
Field Studies ◽  
Temporal Variations ◽  
Pseudokirchneriella Subcapitata ◽  
Relative Importance ◽  
Freshwater Bivalve ◽  
Cd Accumulation ◽  
Pyganodon Grandis ◽  
Biodynamic Model

For this study, the unionid bivalve Pyganodon grandis was either exposed to dissolved cadmium (Cd) or fed Cd-contaminated algae ( Pseudokirchneriella subcapitata ) during short-term laboratory experiments. Cadmium accumulated largely in the digestive gland after a dietary exposure, or in the gills after an aqueous exposure; in these latter experiments, Cd accumulation from the dissolved phase increased as bivalve filtration rates increased. The results of these uptake experiments were used to parameterize a biodynamic model, which was then used to estimate the relative importance of water and food as sources of Cd for this bivalve, and to predict steady state Cd concentrations in the gills and digestive gland of native bivalves. In comparisons between the simulations and data obtained from earlier field studies on P. grandis, the model adequately predicted Cd concentrations in P. grandis gills, except in Ca-rich lakes, whereas it tended to overestimate Cd concentrations in the digestive gland. The field simulations indicate that water is the main source of Cd for both the gills (relative importance water:food::99:1) and the digestive gland (water:food::80:20). These results will facilitate the interpretation of spatial and temporal variations in Cd concentrations in free-living P. grandis, which is a promising metal biomonitor.

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