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 photosynthetic apparatus was more degraded in younger control seedlings and for a longer time UV-B treated seedlings than in the older or for a shorter time UV-B treated seedlings. This was shown by determining the losses in chlorophyll (Chi) and protein contents, variable fluorescence yield, photosystem(PS) 2, PSI and ribulose-1,5-bisphosphate carboxylase (RuBPC) activities, and photosynthetic (CO2)-C-14 fixation. In contrast, the Car/Chl ratio increased during the dark incubation due to less expressed degradation of Car.