DIFFERENTIAL RESPONSE OF FERN LEAVES TO SENESCENCE MODULATING AGENTS OF ANGIOSPERMIC PLANTS

Senescence of fern leaflets in darkness is characterised by the loss of pigments. The cations, Ca+2 and Mg+2, regulate leaf senescence differently; magnesium retards the process continuously both in light and dark whereas calcium retards the process at an initial phase and subsequently stimulates the process in dark. The ions however, retard chlorophyll loss significantly in light compared to the control throughout the experimental period. The loss of chlorophyll during senescence is retarded by cycloheximide. Chloramphenicol does not exhibit any modulating effect on pigment loss. The senescence retarding effect of actinomycin-D, a response not observed in the leaves of higher plants, suggests control of fern leaf senescence at the level of transcription. Dark plus kinetin treatment of fern leaflets exhibits a significant protecting effect on chlorophyll loss compared to continuous white light (2500 lux). © 1990, Gustav Fischer Verlag, Stuttgart. All rights reserved.