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

Abstract

Introduction: Celastrus paniculatus (Family: Celastraceae) is a woody climbing shrub valued for its immense medicinal properties contained in its various plant parts. Over-exploitation and poor natural regeneration either by seed or other method/s have resulted into depleting population of C. paniculatus in natural habitats in India. Novel approaches such as liquid culture media and photoautotrophic multiplication of shoots on sugar-free media has proved useful to obtain photosynthetically active micropropagated plantlets. Methods: The shoot cultures of C. paniculatus were multiplied on sucrose containing and sucrose-free semi-solid and liquid media. The cultures were further incubated under various concentrations of carbon dioxide (0.0 to 40.0 gm-3). The assessment of chlorophyll fluorescence parameters (Fo, Fm, F'm, Ft, Fv/Fm and ΦPS2) under similar conditions was undertaken. Results: It was observed that CO2 enrichment favored shoot multiplication and elongation and biomass production in sucrose supplemented medium. CO2 (10.0 gm-3) along with sucrose (3.0%), recorded maximum growth on semi-solid and liquid media. The valuation of Fo, Fm, F'm, Ft, Fv/Fm and ΦPS2 revealed that an increase in the concentration of CO2 resulted in a decline in all the parameters especially the Fv/Fm and ΦPS2. On the contrary, withdrawal of sucrose from the medium under CO2 enriched conditions resulted in a moderate growth rate and biomass production. However, Fv/Fm and ΦPS2 were considerably improved in shoot cultures incubated under elevated concentrations of CO2 (10.0 gm-3) without sucrose in the medium indicating their photoautotrophic growth. Conclusions: Liquid medium proved to be superior for overall growth and biomass production over its semi-solid counterparts. The observations of photochemical efficiency in shoot cultures grown on liquid medium were at par with their semi-solid counterparts indicating no adverse effects such as hyperhydricity.