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  • 1
    Electronic Resource
    Electronic Resource
    On the opportunity cost of the photosynthate invested in stem elongation reactions mediated by phytochrome (1991)
    Springer
    Oecologia 86 (1991), S. 561-567 
    Details
    ISSN: 1432-1939
    Keywords: Canopies ; Competition ; Light quality ; Photosynthate partitioning ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Seedlings of shade-intolerant species react to alterations of the light climate caused by their neighbors with morphological changes that may influence the pattern of resource acquisition and utilization at the whole-canopy level. One such change, the increased stem elongation rate that is triggered by low red (R, 660 nm) to far-red (FR, 730 nm) ratios (R:FR) in dense canopies, might reduce the amount of assimilates available for leaf area expansion or root growth, and in that way affect resource capture by the canopy. We have tested this hypothesis by comparing the growth of both isolated individuals and canopies of the weed Amaranthus quitensis under conditions differing only in the spectral distribution of the incident light. When canopies received the full spectrum of sunlight, the stems were a large proportion (40–57%) of total biomass. Filtering the FR waveband (and hence raising the R:FR ratio to eliminate the neighbors' proximity-signal) resulted in shorter canopies with lighter stems. However, the growth of leaves and roots was not promoted by this treatment, indicating that the opportunity cost of the assimilates invested in the stems was nil or very small. Filtering the FR had no effect on biomass accumulation when plants were grown as isolated individuals. The higher growth of the canopics under full spectrum could be due to a higher light interception or to a higher efficiency of light conversion into biomass. The first possibility is weakened by the observation that filtering the FR had no effect on the dynamics of soil covering by the crops. The second is indirectly strengthened by results of an experiment with isolated plants showing that stem elongation, stem growth, and total plant biomass can be increased by reducing the flux of R light received by the stems without affecting the light climate of the leaves. Further work is needed to distinguish between these two possibilities; whatever the cause, our results show that the elongation responses to decreased R:FR may lead to a net increase in canopy productivity, and do not necessarily have a negative impact on the growth of resource-harvesting organs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318323
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Morphological responses of Datura ferox L. seedlings to the presence of neighbours (1988)
    Springer
    Oecologia 76 (1988), S. 288-293 
    Details
    ISSN: 1432-1939
    Keywords: Datura ferox ; Plant density ; Neighbour detection ; Canopy microclimate ; Light quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We studied the effects of density on the dynamics of seedling growth and canopy microclimate within experimental stands composed of Datura ferox L. seedlings grown in individual pots. Interception of photosynthetically active radiation (PAR) by seedlings was evaluated either indirectly, by measuring leaf area, proportion of leaf area shaded by neighbouring individuals and laminar orientation with respect to sunlight, or directly, by measuring PAR at individual leaves at their natural angle of display. An integrating cylinder, with a geometry approximating that of a stem, was used within the canopies to measure the red:far-red (R:FR) ratio of the light flux from all compass points parallel to the soil surface. Seedlings responded rapidly (i.e. 1–2 weeks) to increased density by producing longer internodes and partitioning more dry matter to stems relative to leaves. These responses were observed before either PAR interception of growth rate were reduced by the presence of neighbours. Conversely, morphogenetic adjustment was preceded by a consistent effect of plant density on the R:FR ratio of the light received by the integrating cylinder. Air and soil temperature were not affected by density in these experiments. Differences in wind velocity within the canopy associated with plant density were avoided by the experimental procedure. The results support the idea that the drop in R:FR ratio of the light flux parallel to the ground — e.g. reflected sunlight — is an early signal that allows rapid adjustment of plant form to changes in canopy structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379965
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    Paper (German National Licenses)
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  • 3
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    Unknown
    Informe Final. Monitoreo y análisis de las operaciones de pesca conjunta del pez espada CE/Chile. Programa de investigaciones del pez espada en las aguas internacionales del Pacífico Sur Oriental. (2015)
    Instituto de Fomento Pesquero | Valparaíso, Chile
    Details
    Publication Date: 2021-05-19
    Description: El objetivo de esta investigación es conocer las pesquerías de pez espada que se configuran en aguas internacionales del pacífico Sur Oriental, frente a las costas de Chile, precisando su localización y estacionalidad, niveles de captura, esfuerzo de pesca, rendimientos y composición de tamaños.
    Description: The objective of this research is to understand the swordfish fisheries that are set in international waters of eastern South Pacific, off the coast of Chile, indicating their location and seasonality, catch levels, fishing effort, yield and size composition.
    Description: Unpublished
    Keywords: Pelagic fisheries ; Sexual maturity ; Stock assessment ; Biomass ; Longlining ; Biological data ; Age determination ; Length-weight relationships
    Repository Name: AquaDocs
    Type: Report , Non-Refereed , Article
    Format: 190pp.
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  • 4
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    Informe Final Evaluación del stock desovante de anchoveta en la I y II Regiones, año 2 007. FIP N° 2007-01. (2015)
    Instituto de Fomento Pesquero | Valparaíso, Chile
    Details
    Publication Date: 2021-05-19
    Description: El principal objetivo de este proyecto es la conservación de los recursos hidro-biológicos de la anchoveta en la I y II regiones, considerando tanto aspectos biológicos, pesqueros y económicos y sociales
    Description: The aims of this project is the conservation of aquatic resources of the anchovy in the I and II regions, we consider both biological, fisheries and economic and social.
    Description: Submitted
    Keywords: Pelagic fisheries ; Bathymetric data ; Stock assessment ; Recruitment ; Trap fishing ; Biomass ; Size-at-age ; Landing statistics ; Eggs ; Aquaculture ; Reproductive behaviour ; Length-weight relationships ; Scomber japonicus ; Trachurus murphyi ; Engraulis ringens
    Repository Name: AquaDocs
    Type: Report , Non Refereed
    Format: 181pp. & Figuras
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