Influence of in vitro environment on somatic embryogenesis of Coffea arabica L. cv. Caturra rojo: the effects of carbon dioxide on embryogenic cell suspensions

The influence of environment in the culture vessel is a factor that has very little study in the process of somatic embryogenesis. The present research was carried out with the objective to determine the effects of carbon dioxide on somatic embryogenesis of Coffea arabica cv. Caturra rojo. Embryogenic cell suspensions were cultured under different carbon dioxide concentrations (2.5%, 5.0%, and 10.0%) in the gases mixture and two control treatments, one with passive exchange and the other with forced ventilation. The results demonstrated that there were a larger number of somatic embryos formed with a concentration of 2.5% CO2. The differentiation of these somatic embryos of coffee in embryogenic cell suspensions (130 × 103 SE l−1) was also stimulated. The effects of CO2 on somatic embryogenesis were demonstrated when the control with passive exchange was compared with forced ventilation control, because in the former, where there was an accumulation of CO2, the production of somatic embryos was greater. CO2 could stimulate the formation and differentiation of somatic embryos directly, which led to a modification of the pH patterns of the culture medium or indirectly when producing changes in the pH that favored the somatic embryogenesis process.