Wirkung von Lichtqualität und Lichtquantität auf die Konkurrenz zwischen der Schattenpflanze Lamium galeobdolon (L.) Crantz und der Halbschattenpflanze Stellaria holostea L.

Abstract

1. Lamium galeobdolon (L.) C rantz (shadow plant) and Stellaria holostea L. (half-shadow plant) were cultivated in mixed culture in open air at 100% (full d light) and 1.8% (shadow) relative light intensity, and likewise in climatic chambers under red light (2.7 %), blue light (6.3 %) and red and blue light including a small portion of white light (4.6 % relative light intensity). The number and length of shoots, leaf area per plant, leaf area per soil surface (leaf area index) and per leaf weight (specific leaf area), dry matter production, contents of chlorophyll, protein nitrogen and soluble nitrogen were all measured. 2. 2. A number of the effects of light intensity and light quality were recorded that were similarly observed in pure cultures in an earlier investigation (W erner et al., 1982). 3. In full day light Stellaria was the stronger competitor, whereas Lamium was stronger under low light intensities. In pure culture both species exhibited an (autecological) optimum of dry matter production in full day light. In mixed culture only Stellaria maintained this optimum, whereas Lamium showed a new (synecological) optimum at lower light intensities. 4. 4. There were only a few indications to support the view that Lamium is favoured by blue light in contrast to red light under competing conditions. If light quality playa role at all in the natural habitat, it is undoubtedly overshadowed in importance by the effect of light intensity.