CHANGES OF 6-BENZYLAMINOPURINE AND 2,4-DICHLOROPHENOXYACETIC ACID CONCENTRATIONS IN PLANT-TISSUE CULTURE MEDIA IN THE PRESENCE OF ACTIVATED-CHARCOAL

The rate of adsorption of 6-benzylaminopurine (BAP) and 2,4-dichlorophenoxyacetic acid (2,4-D) by activated charcoal (AC) from liquid and semi-solid tissue culture media was determined using 8-[C-14]-BAP and 2-[C-14]-2',4'-D. For both liquid and semi-solid media an essentially constant ratio of free BAP:AC-bound BAP was reached between 5 and 10 days after preparation of the media. Pronounced increases in the level of available 2,4-D in the medium occurred, when either the initial BAP or 2,4-D level or both were raised to 5 x 10(-4) M. When 2,4-D was used at 5 x 10(-4) M the medium component sucrose (40 g l-1) caused a pronounced increase in available 2,4-D. Conversely the inclusion of the combined macro- and micronutrients markedly reduced the availability of free 2,4-D in the medium.