Wyniki wyszukiwania

1

Effect of calcium restriction on cardenolide accumulation in two cell lines of Digitalis thapsi grown under differend light regimes

100%

Cacho M., Moran M., Corchete P., Fernandez-Tarrago J.

Acta Physiologiae Plantarum

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1999

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tom 21

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nr 4

2

Biomass allocation, compensatory growth and internal C/N balance of Lolium perenne in response to defoliation and light treatments

84%

Wang L., Wang J., Liu W., Gan Y., Wu Y.

Polish Journal of Ecology

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2016

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tom 64

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nr 4

Light environments can have a considerable influence on how plants respond to defoliation through influencing the biomass allocation patterns and internal C/N ratio. Seedlings of Lolium perenne, a common perennial grass species, were grown for eight weeks under three different light environments (natural light, red light and shading) and two different defoliation treatments (no defoliation versus 50% aboveground biomass removal). This study was conducted to examine (1) the effects of light regimes and defoliation on biomass accumulation, biomass allocation and internal C/N ratio status in plants; (2) how the light regimes influence the pattern of compensatory growth after defoliation; and (3) the relationship between compensatory growth and the internal C/N ratio status. We found that red light altered the shoot-to-root allometry, enhanced the leaf C concentrations and induced N deficiency. By contrast, the leaf N concentrations of L. perenne were greater during shading treatment, which simultaneously enhanced shoot growth and stopped root growth. Under defoliation, red light increased shoot growth, not at the expense of root growth, which was not the same as in natural light and shading treatment. Moreover, regardless of the unclipped (no defoliation) and defoliation conditions, the L. perenne biomass partitioning between roots and shoots was significantly correlated with the leaf N concentrations and C/N ratio, indicating that allometric biomass allocation can be largely modulated by signals related to the C and N status of the plants. These results demonstrated that the leaf C and N status would be an appropriate indicator of compensatory growth after defoliation.

3

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Acer truncatum seedlings are more plastic than Quercus variabilis seedlings in response to different light regimes

84%

Guo X., Wang R.-Q., Wang C. D., Xu F., Zhao S., Guo W.-H.

Dendrobiology

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2016

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tom 76

In this study, we investigated responses of the mid-successional species Acer truncatum Bunge and the late-successional species Quercus variabilis Blume to three solar illumination conditions: (1) constant low light (CL), (2) constant high light (CH) and (3) low light first and high light afterwards (LH). The last treatment was to simulate a canopy opening. Both species exhibited increases in biomass, totally and in part, and decreases in leaf water content, specific leaf area and chlorophyll concentrations in LH treatment compared to CL treatment. For A. truncatum, exposure to high light condition (LH) increased crown area, and decreased root to shoot ratio, stem mass ratio and leaf perimeter. However, for Q. variabilis, LH treatment increased stem diameter at ground height, effective quantum yield, photochemical quenching and decreased maximum photosystem II quantum yield. The biomass allocation pattern did not change in Q. variabilis among three light conditions. With respect to newly developed leaves, no significant differences were found in leaf size of Q. variabilis between LH treatment and CH treatment while that of A. truncatum decreased in LH treatment. All chlorophyll fluorescence parameters in newly developed oak leaves in LH treatment increased compared to those of CH treatment while no difference was found for A. truncatum between LH and CH treatment. A. truncatum displayed a greater overall plasticity than Q. variabilis although the oak seedlings have a greater plasticity with respect to chlorophyll concentration and chlorophyll ﬂuorescence parameters. A. truncatum should be a better candidate for vegetation recovery, especially in places with heterogeneous light conditions.

4

Simulation of light regimes in typical subalpine forest succession series of Eastern Tibetan Plateau

67%

Wang Q., Wu N., Luo P.

Polish Journal of Ecology

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2009

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tom 57

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nr 2

251-260

Natural regeneration of forest depends on the light regimes of floor. Point-based methods such as fisheye photo and radiometer can not provide a full panorama of light regime of heterogeneous forest stand. Eastern Tibetan Plateau is a major forest belt characteristic of diverse forest type and topographic differentiation. Understanding the trend of changes of light regime along succession series of forest may be helpful for the management of ecosystems. Fragmented forest patches due to tectonic activity and human intervention have made this prediction difficult. We use a spatially explicit forest stand light model (tRAYci) to simulate light distribution within forest in typical subalpine forest succession series of eastern Tibetan Plateau. Due to the spatial heterogeneity of tree distribution in the subalpine area, the forest stand can be approximated with a spatially explicit model of trees. Three typical subalpine forest stands (Sabina forest (SF), Fir forest (FF) and Birch forest (BF)) are selected in the eastern Tibetan Plateau. The dominant species are sabina (Sabina saltuaria (Rehd. et Wils.) Cheng), fir (Abies faxoniana Rehd. et Wils.) and birch (Betula platyphylla Suk.) for each stand and they are spatially clumped in distribution. They represent old growth coniferous forest (SF, 330 years old), coniferous-broadleaved forest (FF, 180 ys) and pioneer broadleaved forest (BF, 40 ys). The parameters of the three-dimensional model of trees are calibrated with field measurements. The simulated values are generally consistent with observed values of radiation measured by radiometers installed in these stands and values derived from fisheye photos. Test failures may be caused by the incomplete submodel of crown as a gap free one. Light regimes in old growth and pioneer forest are much more heterogeneous than intermediate stages of forest. Light regimes of these forests are also reflected by the composition of understory herb layers.

5

Vascular ground flora in relation to topography, canopy structure and gap light regimes in a subtropical broadleaved forest (South China)

67%

Ou Y.-D., Su Z.-Y., Ke X.-D., Li Z.-K.

Polish Journal of Ecology

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2012

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tom 60

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nr 3

We examined the influence of topogra phy, canopy structure and gap light environmental variables on the patterns of vascular ground flora (vascular plants less than 1 m in height excluding tree seedlings) in a subtropical broadleaved forest in S China, using field data obtained from a 4-ha permanent plot. Both topographic and canopy environmental conditions had a significant effect on community composition, species diversity and distribution of the vascular ground flora. However, topographic factors, especially slope position and aspect, had a greater influence as compared with canopy and understory light conditions. Both number of individuals and number of individuals per species of the ground flora varied significantly with different slope position, aspect, slope steepness and transmitted direct radiation, while species richness varied significantly under different slope position and canopy leaf area index (LAI) The effects of topographic and canopy environmental conditions on ground-flora composition and structure was further confirmed by Canonical Correspondence Analysis (CCA). Multi-response Permutation Procedures (MRPP) showed significant differences in the ground-flora species composition based on all the topographic, canopy structure and gap light variables. Species indicative of topographic, canopy structure and gap light regimes were identified with a significant indicator value (IV ≥ 35%) by Indicator Species Analysis (ISA), which indicated that certain species have their ecological preference for a particular environmental gradient.

6

Day-night food consumption in mice is strain and age-dependent

67%

Kowal M., Buda-Lewandowska D., Plytycz B., Styrna J.

Folia Biologica

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2002

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tom 50

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nr 1-2

7

Serum melatonin, corticosterone and thyroid hormones in irradiated rats: effect of exposure during various times of day of light regimen

67%

Ahlersova E., Kassayova M., Ahlers I.

Journal of Physiology and Pharmacology

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1997

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tom 48

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nr 3

Ograniczanie wyników

Effect of calcium restriction on cardenolide accumulation in two cell lines of Digitalis thapsi grown under differend light regimes

Biomass allocation, compensatory growth and internal C/N balance of Lolium perenne in response to defoliation and light treatments

Acer truncatum seedlings are more plastic than Quercus variabilis seedlings in response to different light regimes

Simulation of light regimes in typical subalpine forest succession series of Eastern Tibetan Plateau

Vascular ground flora in relation to topography, canopy structure and gap light regimes in a subtropical broadleaved forest (South China)

Day-night food consumption in mice is strain and age-dependent

Serum melatonin, corticosterone and thyroid hormones in irradiated rats: effect of exposure during various times of day of light regimen