Plant Growth Regulator Stock Solution Preparation
Small amounts of plant growth regulators elicit large responses in plants. Generally in
tissue culture medium plant growth regulator concentrations range from mM to nM.
Therefore concentrated stock solutions are prepared and added to the medium. Since
most medium contain PGRs in the µM range, the following calculations will be based on
a medium containing 1 µm.
1. A 1 Molar (M) solution is the molecular weight, expressed in grams, of a solution
which has been dissolved in 1 liter of the final solution. The molecular weight
can be found on the container. i.e. BA (benzyladenine) molecular weight is 225.2
1 M BA = 225.2 g in one liter final volume
2. A 1 milliMolar (mM) solution is the molecular weight, in milligrams, of a solution
which has been dissolved in 1 liter of the final solution. 1 mM BA = 225.2 mg in
one liter final volume or 22.52 mg in 100 ml final volume
3. Not all PGRs will dissolve in water. A solvent must be used. Generally, auxins
may be dissolved in ethanol, cytokinings in KOH, gibberellins in ethanol and
abscisic acid in ethanol.
4. Accurately weigh the appropriate amount of PGR to be used. Place a few mls of
the appropriate solvent in a volumetric flask and add PGR. Wash the weigh
paper and the sides of the volumetric flask with a little more solvent. Swirl
volumetric flask until PGR is dissolved, adding a little more solvent if needed. Fill
the flask to the final volume with distilled water.
5. To use PGR stock solution:
For a 1 mM use 1000 ml PGR 10-3 stock in 1 liter final volume
For a 100 µM use 100 ml PGR 10-3 stock in 1 liter final volume
For a 10 µM use 10 ml PGR 10-3 stock in 1 liter final volume
For a 1 µM use 1 ml PGR 10-3 stock in 1 liter final volume
For a 0.1 µM use 0.1 ml PGR 10-3 stock in 1 liter final volume