BIOREACTOR STUDIES OF THE EFFECT OF MEDIUM PH ON CARROT (DAUCUS-CAROTA L) SOMATIC EMBRYOGENESIS

Daucus carota cell differentiation was examined under different medium pH conditions in a controlled bioreactor. Somatic embryogenesis was a ffected by pH changes. Embryo production was greatest when the pH of t he hormone-free medium was maintained at 4.3. However, the same level was not favourable to development since most embryos did not progress to the torpedo and plantlet stages. In contrast, although there was ab out a threefold decrease in embryo yield in cultures on the same free 2,4-dichlorophenoxyacetic acid medium maintained at pH 5.8, cells diff erentiated into fully developed plantlets. Changes in embryo developme nt appeared to be associated with alterations in ammonium loss from th e medium and sugar uptake.