CHANGES IN PHOTOSYNTHETIC APPARATUS DURING DARK INCUBATION OF DETACHED LEAVES FROM CONTROL AND ULTRAVIOLET-B TREATED VIGNA SEEDLINGS

Changes in various components of photosynthetic apparatus during the 4 d dark incubation at 25 degrees C of detached control and ultraviolet -B (UV-B) treated Vigna unguiculata L. leaves were examined. The photo synthetic apparatus was more degraded in younger control seedlings and for a longer time UV-B treated seedlings than in the older or for a s horter time UV-B treated seedlings. This was shown by determining the losses in chlorophyll (Chi) and protein contents, variable fluorescenc e yield, photosystem(PS) 2, PSI and ribulose-1,5-bisphosphate carboxyl ase (RuBPC) activities, and photosynthetic (CO2)-C-14 fixation. In con trast, the Car/Chl ratio increased during the dark incubation due to l ess expressed degradation of Car.