CHANGES IN LEAF PROTEIN AND PIGMENT CONTENTS AND PHOTOSYNTHETIC ACTIVITIES DURING SENESCENCE OF DETACHED MAIZE LEAVES - INFLUENCE OF DIFFERENT ULTRAVIOLET RADIATIONS

Senescence induced loss in pigments and proteins of detached maize (Ze a mays L., cv. Col) leaves was significantly enhanced on the exposure of leaves to different ranges of ultraviolet (UV) radiation, Compared to W-A (320-400 nm) and W-B (280-320 nm), the W-C (200-320 nm) was the most damaging for the pigments and macromolecules, A severe decline i n photosystem (PS) 2 mediated photoreduction during senescence of deta ched leaves exposed to UV irradiation suggested a damage of the system , The PS1 mediated photoreduction of methylviologen with 2,6-dichlorop henol indophenol as electron donor was stimulated by UV-A and UV-B rad iations, suggesting a reorganisation of the PS1 complex, These results were fortified by the values of fast and slow kinetics of chlorophyll (Chi) a fluorescence transients.