In vitro growth and shoot multiplication of Wrightia tomentosa Roem et Schult in a controlled carbon dioxide environment

Abstract

In vitro growth and multiplication of shoots of a woody tree species Wrightia tomentosa in a controlled carbon dioxide environment was studied. The cultures were grown on BA supplemented MS medium with or without 3% sucrose. A range of CO₂ concentrations (0.0, 0.6, 10.0 and 40.0 g m⁻³) was controlled in small chambers by using solutions of NaHCO₃, Na₂CO₃, KHCO₃ and K₂CO₃. To obtain a CO₂-free environment, a saturated solution of KOH was kept in the chambers. It was concluded that the growing shoot cultures required either sucrose in the medium as a carbon source or an ambient CO₂ environment. Complete absence of a carbon source caused severe browning of the shoots and death within 30 days. The cultures grew better with 10.0 g m⁻³ carbon dioxide in the environment than with 3.0% sucrose in the medium. With both CO₂ and sucrose being available, the best response was obtained at 0.6 g m⁻³ CO₂ in the chamber. At this concentration the rate of shoot multiplication was nearly double the standard rate obtained when exposed to the natural CO₂ level and sucrose-supplemented medium. Total fresh and dry weight, leaf number and area per cluster also showed the best response under this condition.