Abstract
This study was undertaken to promote saikosaponins accumulation in the leaves of a medicinal plant, Bupleurum falcatum, grown in solution culture. Effects of air temperature, relative humidity (R.H.), photosynthetic photon flux density (PPFD), photoperiod and CO2 concentration on growth and saikosaponin production were investigated using growth chambers with fluorescent lamps. Maximum leaf dry weight (mg⋅plant-1) and saponin content (mg⋅plant-1) were obtained at 25/25°C (photoperiod/dark period air temperature) . The growth was proportional to R.H., while saponin concentration (% dry wt) was gradually decreased with the increase in R.H. Therefore, saponin content reached a peak at 80% R.H. Leaf dry weight changed with photoperiod from 12 to 20 h⋅d-1. Further extension of photoperiod suppressed the growth, however. Increase in PPFD gave high saponin concentrations. A low PPFD (106μmol⋅m-2⋅s-1) and a photoperiod of 20 h⋅d-1 provided high efficiencies of dry matter production and saponin production. There was no effect of CO2 enrichment.
