Photosynthetic efficiency and in vitro growth of Celastrus paniculatus Willd. under varied concentrations of CO2

Abstract

Introduction: Celastrus paniculatus \n(Family: \nCelastraceae) is a woody climbing shrub valued for its immense medicinal \nproperties contained in its various plant parts. Over-exploitation and poor \nnatural regeneration either by seed or other method/s have resulted into \ndepleting population of C. paniculatus \nin natural habitats in India. Novel approaches such as liquid culture media and \nphotoautotrophic multiplication of shoots on sugar-free media has proved useful \nto obtain photosynthetically active micropropagated plantlets. \n \nMethods: The shoot cultures of C. paniculatus were multiplied on sucrose containing and \nsucrose-free semi-solid and liquid media. The cultures were further incubated \nunder various concentrations of carbon dioxide (0.0 to 40.0 gm-3). \nThe assessment of chlorophyll fluorescence parameters (Fo, Fm, \nF m, Ft, Fv/Fm and ΦPS2) under \nsimilar conditions was undertaken. \n \n Results: It was observed that CO2 enrichment \nfavored shoot multiplication and elongation and biomass production in sucrose \nsupplemented medium. CO2 (10.0 gm-3) along with sucrose \n(3.0%), recorded maximum growth on semi-solid and liquid media. The valuation \nof Fo, Fm, F m, Ft, Fv/Fm \nand ΦPS2 revealed that an increase in the concentration of CO2 \nresulted in a decline in all the parameters especially the Fv/Fm \nand ΦPS2. On the contrary, withdrawal of sucrose from the medium under CO2 \nenriched conditions resulted in a moderate growth rate and biomass production. \nHowever, Fv/Fm and ΦPS2 were considerably improved in \nshoot cultures incubated under elevated concentrations of CO2 (10.0 \ngm-3) without sucrose in the medium indicating their \nphotoautotrophic growth. \nConclusions: Liquid medium proved to be superior for overall \ngrowth and biomass production over its semi-solid counterparts. The \nobservations of photochemical efficiency in shoot cultures grown on liquid \nmedium were at par with their semi-solid counterparts indicating no adverse \neffects such as hyperhydricity.