Influence of potential growth factors on the production of proembryogenic masses of Cyclamen persicum Mill. in bioreactors

Propagation in liquid culture, especially bioreactors, is one possible way to produce clonal propagules of Cyclamen persicum Mill. at a low cost. The current propagation method for C. persicum is from expensive hybrid seeds. This paper presents models of the potential effects of oxygen concentration, daily mean temperature, the difference between day and night temperature (DIF), and daily light integral on the development of proembryogenic masses of C. persicum Mill. in bioreactors. Each of the four growth factors was observed at three levels; oxygen concentration (50, 100 and 150% of fully oxygen saturated medium without cells), daily mean temperature (15, 20 and 25 °C), DIF (+10, 0 and −10) and daily light integral (0, 1.3 and 2.6 mol m⁻² day⁻¹). Two response variables, biomass growth and cell viability, were measured at day 0, 7, 14, 21 and 28 after start-up. The optimal values for biomass growth were 150% oxygen, 25 °C, 1.11 mol m⁻² day⁻¹ and DIF + 10. There was a stable positive linear effect from temperature. Oxygen showed a similar, but less stable effect. DIF gave maximum effect at the outer levels, and its optimum was the upper level +10. The optimal values for light were between 1.03 and 1.19 mol m⁻² day⁻¹. The optimal time for cell viability in the bioreactors was 10–11 days. Temperature and daily light integral had stable optima of 20.8 °C and 1.10 mol m⁻² day⁻¹. For oxygen the optimum was more unstable, but in most cases it was below 100%. There was no significant effect of DIF on cell viability.