Contrasting the results of photosynthesis and chlorophyll fluorescence, the experimental treatments had only a minor influence on the Chl-index(Fig. 10). On the last day of the UV irradiation 30% B showed a significantly higher Chl-index as compared to the other treatments. However,the analysis of the chlorophyll concentration indicates that UV treated plants(30% B+UV, 62% B+UV) had significantly less Chl a and Chl b (data notshown), resulting in lower concentration of total chlorophylls (Table 2). There by,we observed a more pronounced reduction in Chl and carotenoids in those plants grown under a lower portion of blue light