Photosynthesis Activity in Some Plants Grown under Enhance Solar UVB (280-320nm) Radiation: A Comparative Analysis

In the experiment conducted in field condition, the seedlings a few days old subjected to enhanced UVB radiation for several weeks. The photosynthetic activity and chlorophyll a fluorescence were analyzed and the variable/maximum fluorescence was calculated. A significant effect of UV-B on PS II activity was observed on Carrot, Beetroot, Radish and onion plants. UV-B radiation in radish plant does not affect its PSII activity instead increases its activity by 50%. At the same time the effects of UVB radiation on other plants such as carrot, oinion and beetroot are visble through the PSII activity. Damage caused by UVB radiation cannot be repaired by those plants. This is demonstrated by reduction of PSII activity and efficiency of Chl fluorescence induction kinetics. However, the UVB radiation did not affect or slightly affect the PSI activity and Fluorescence parameter. The result demonstrates that the effect of UV-B radiation in the tropical region may significantly lower the photosynthetic activity in plants that cannot withstand the effects of UV-B radiation and higher in plants that tolerate it.