Universität Stuttgart

Permanent URI for this communityhttps://elib.uni-stuttgart.de/handle/11682/1

Browse

Publication Type: search.filters.UBSTyp.ZeitschriftenartikelAuthor: search.filters.author.Herbig, Astrid

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Seasonal trends in energy content and storage substances in the mediterranean shrub Ephedra
    (1989) Diamantoglou, Stergos; Rhizopoulou, Sophia; Herbig, Astrid; Kull, Ulrich
    Green branches of a shrub of Ephedra distachya L., growing in Athens, Greece, were investigated. The crude fibre content rises during the late growth period, levels off during winter, then declines as new shoots emerge in spring. The content of soluble sugars and of starch is high during winter, but rather low during the dry season. The content of total lipids rises during winter, especially during the late growth period until June and declines during the drought period. During the winter months in the total saponifiable lipids the percentage of linoleic and linolenic acids is high; however, during the growth and the drought period the content of palmitic acid is rather high. The contents of total nitrogen and protein nitrogen decrease in late spring and remain low until the end of the summer drought. Thereafter, both values rise markedly. Stored energy is lowest at the end of the summer drought period. The ashfree calorific values vary little throughout the year (but the difference is significant) : the highest value is obtained in November (19782 J/g), the lowest in May (19298 J/g). From our data, the tissue.construction cost was estimated to be 1.41-1.47 g glucose/g dry weigth. Ephedra distachya is suited to the mediterranean climate, as seen by its ability to adjust to climatic changes during the year while undergoing periods of growth and quiescence. The accumulation of sugar during the winter months suggests that Ephedra is also capable of growing under cold-stress conditions.
  • Thumbnail Image
    ItemOpen Access
    Pflanzen als natürliche Konstruktionen - oder das Prinzip Leichtbau
    (1987) Kull, Ulrich; Herbig, Astrid
    Unter den natürlichen Konstruktionen nehmen Pflanzen einen wichtigen Platz ein. Da Landpflanzen ortsfest sind, darf man erwarten, daß Analogien zu Architekturleistungen des Menschen bestehen. Bei der Bearbeitung natürlicher Konstruktionen sind daher Untersuchungen über konstruktive Eigenschaften von Pflanzen von großer Bedeutung. Hier soll dargestellt werden, welche Aspekte der Konstruktion von Pflanzen (beschränkt auf Landpflanzen) derzeit vor allem bearbeitet werden und welche Untersuchungen im Rahmen der Erforschung natürlicher Konstruktionen wir im Rahmen des Sonderforschungsbereichs 230 begonnen haben.
  • Thumbnail Image
    ItemOpen Access
    Construction and economy of plant stems as revealed by use of the Bic-method
    (1992) Kull, Ulrich; Herbig, Astrid; Otto, Frei
    The Bic-method, developed by F. Otto for the investigation and classification of light-weight structures in architecture and then also applied to constructions in nature, can be used for mechanical analysis of plants. It allows statements on tension and pressure stability of plant stems and a direct comparison of stems with different anatomy. The multiplication of the Bic-value by an energy value (construction cost or energy content of the plant organ) results in a dimensionless constructive expenditure value, which is comparable to the value of the construction economy in architecture. This value may then be related to the average lifespan of the plant organ. Stems of Ephedra foeminea, Pachysandra terminalis, and Taxus baccata as well as flower stalks of Cyclamen persicum and Taraxacum officinale are investigated to show the applicability of the method. The lowest Bic- values (highest mechanical stability) are found for the lignified stems of Ephedra and Taxus. The constructive expenditure values are higher in herbaceous than in woody axes; in relation to the average life span the long-living lignified tissues show by far the lowest values. The very high values of the flower-stalks are attributed to the fact that short-lived organs also need a minimum expenditure of materials and energy for their construction.