EFFECT OF LIGHT-INTENSITY ON CHLOROPHYLL CONTENT IN IMPATIENS-FLANAGANIAE

Unbranched plantlets of I. flanaganiae propagaged from tubers were exp osed to three light regimes: 30, 55 and 280 microeinsteins m(-2) sec(- 1) for seven weeks. Chlorophyll content increased in the leaves of pla nts grown under low light intensity (30-55 microeinsteins m(-2) sec(-1 )) during the third and fourth weeks, after which it steadily declined . The chlorophyll level of the leaves from these plants was significan tly (at 5% level) higher from the second week onward as compared to th e leaves exposed to high intensity (280 microeinsteins m(-2) sec(-1)). Under high intensity chlorophyll concentration markedly declined and symptoms of chlorosis developed, especially in the upper leaves. Sever e chlorosis predominated in the leaves of plants sprouted under high l ight intensity right from the beginning. The effects of increasing lig ht intensity on chlorophyll levels are discussed in relation to photoo xidation of thylakoid constituents by activated O-2 species.