[EN] In mature leaves of chlorotic plants (pear-trees, peanuts) which are grown in calcareos soils, the high intensity of light increases the photodescomposition of chlorophyll. The relation between chlorophyll a and chlorophyll b is higher in leaves subjected to weak light than in those exposed to natural intense light, due to the greater photolability of chlorophyll b. Under induced iron deficiency, chlorotic symptoms disappear more rapidly by decreasing the intensity of light than by injecting Fe SO4 (0,025%). In both cases the soluble iron content and the catalase activity increase. The relation between ascorbic acid and chlorophyll, which is higher in chlorotic leaves than in green ones, descends when the intensity of light decreases. Ascorbic acid does not avoid the descomposition of the chlorophyll by the intense sunlight, a rôle which coild be played by the polyphenols.

Peer reviewed