Impact of Ultraviolet-c Radiation on Seed Germination and Chlorophyll Concentration of Some Woody Trees Grown in Saudi Arabia

Constant reduction of stratospheric ozone layer and the increase of ultraviolet radiation intensity were observed in last twenty years of the 20th century. Four tree species; Acacia amplicepsis, Acacia gerradii, Casuarina glauca and Eucalyptus intertexta grown in Experimental station of Food and Agriculture Sciences Collage, King Saud University were used to study the impact of UV-C on potential of seed germination and chlorophyll concentration. The result obtained has indicated that, UV-C (254nm) affected significantly the seed germination and chlorophyll concentration. Increased UV-C exposure periods can decrease the chlorophyll A, chlorophyll B and chlorophyll A + B concentrations of seedling of studied species. Similarly, seed germination was also sensitive to high dose of UV-C radiation. Acacia ampliceps was significantly higher in two experiments than the other species in seed germination and chlorophyll A, B and A+ B concentrations. The UV-C exposure periods in the two experiments showed that the exposure periods were highly significant. Moreover, the most affective exposure period on the seed germination was 72 hours. As for the chlorophyll concentration, the control treatment (No exposure) had the highest chlorophyll A, B and A+ B concentrations than the other UV-C exposure periods. The most detrimental exposure period was found at 120 minutes. Chlorophyll ratio was varied among the tree J.Agric.&Env.Sci.Alex.Univ.,Egypt Vol.8 (2)2009 2 species. Acacia gerradii had the highest chlorophyll ratio than the other tree species in the two experiments. In the first experiment, 30 minute exposure period gave the highest chlorophyll ratio, while the lowest chlorophyll ratio was found on control treatment. In contrast, in the second experiment, the highest chlorophyll ratio was found on control treatment (No exposure) and the lowest chlorophyll ratio was 120 minutes. From the results, it is clear that Acacia ampliceps was the most tolerant to the exposure to the Ultraviolet-C (254 nm) radiation and had the highest chlorophyll concentrations, while Eucalyptus intertexta was the most sensitive to same dose of radiation.