Field investigations in Welwitschia mirabilis

Welwitschia mirabilis is endemic to the Namib desert of Angola and Namibia. Within its distribution area it faces severe droughts often accompanied by high radiation and high temperatures. While in the past decade we concentrated on carbon- and water relations of Welwitschia mirabilis we now try to get an answer how the photosynthetic apparatus of this evergreen plant copes with the harsh environment at its growing sites. By means of chlorophyllfluorescence measurements we were able to show a substantial photoinhibition but only in very old parts of the leaf. However, the observed processes favor a down regulation of PS II and other repair and protective mechanisms and by that prevent photodamage. In summary our investigations showed that a main element of the life strategy of Welwitschia mirabilis is to keep a functional leaf blade alive as large as possible. Only this guarantees a quick and beneficial response to the sarce rainfall events.

Drittmittelgeber:

Deutsche Forschungsgemeinschaft

Beteiligte Wissenschaftler:

Dr. W.B. Herppich, Dr. B. M.-T. Flach (Zürich), Prof. Dr. D.J. von Willert, M. Herppich

Veröffentlichungen:

Herppich, W.B., B. M.-T. Flach, D.J. von Willert, M. Herppich: Field investigations in Welwitschia mirabilis during a severe drought. II. Influence of leaf age, leaf temperature and irradiance on photosynthesis and photoinhibition. Flora 192, 165-174 (1997)7