Beschreibung:
<p>The annual savanna grasses Chloris virgata (C₄) and Tragus berteronianus (C₃) and the tree Acacia tortilis were exposed in a greenhouse to elevated UV-B radiation (<tex-math>$16.8\text{kJ}\text{m}^{-2}\text{d}^{-1}\text{UV}-\text{B}_{\text{Be}}$</tex-math>) and to no UV-B and grown on a poor and a rich soil for one life-cycle (grasses) and one growing season (Acacia). UV-B radiation had no effect on biomass production and caryopses mass of both annual grasses. The longevity of the cotyledons of A. tortilis was shortened by 4 to 10 days under enhanced UV-B radiation, which also hampered the translocation of Fe, Mg and Mn from the cotyledons to the seedling and the retranslocation of Mn on both soil types and that of P on fertile soil out of senescent leaves. At the end of the growth period (190 days after germination), photosynthesis of UV-B radiated leaves of A. tortilis was significantly decreased and supported the tendency of decreased biomass of UV-B radiated plants. It is concluded that from the investigated savanna species the grasses are relatively well adapted to increased UV-B due to their actual exposure to high UV-B radiation under Botswana conditions, whereas saplings of A. tortilis are more sensitive to UV-B radiation.</p>