extended periods of time without
loss. However, beware of directions
that recommend 10g /140ml because
this concentration is incorrect.
Calcium hypochlorite is readily
available as a swimming pool disin-
fectant. Read the label (purity varies)
and calculate the amount required to
prepare a 0.5% solution calculated
as (AC) available chlorine, the op-
timum strength. After preparation,
store the extra solution in a glass
bottle in a refrigerator for later use.
A small amount of liquid detergent,
a fraction of a drop, added to the so-
lution just prior to use improves dis-
infection. If you still have some con-
tamination, try pulling a vacuum on
the seed-calcium hypochlorite mix-
ture. My sowing system, in combina-
tion with vacuum treatment, results
in an overall contamination rate of
The Pressure Cooker
1 to 2%.
Do you need to remove the hypochlorite before sowing?
If you start reading about seed sowing, you will almost I don’t know because I always remove it. I know of two
immediately run into poor advice. One example is the methods that can be used for removal—the one I use and
suggestion that you can use a microwave to disinfect your one that uses a large syringe. To use a syringe, first place
media. The maximum temperature
obtainable in a microwave is the
boiling point of water. This is a tem-
perature that pasteurizes but does
not sterilize. If you don’t have access
to an autoclave, a pressure cooker
may be used to sterilize your media
and tools. Here’s another one—af-
ter sterilization, remove the flasks
and place on a clean surface to cool.
This procedure allows the outside of
the flasks to become contaminated.
Leave the flasks in the closed pres-
sure cooker until you are ready to
sow. It is quite common to see the
advice to use a 10% bleach to dis-
infect your seed. Studies run in the
1960s found that contact time was
critical with liquid bleach with 10-
15 minutes being sufficient. Those
studies further demonstrated that
seed could be left in contact with
calcium hypochlorite solutions for
The Glove Box
Phalaenopsis - Fourth Quarter, Vol. 21(2) 2011
9