>Aaron who said: >A good starting place is 10% bleach solution (commercial >bleach locally being a 6% solution of sodium hypochlorite in water) >for 10-15 minutes; rinse 1-2 times with sterile distilled water, and >deposit on fresh medium.
This statement may be somewhat confusing to some people. In Canada the Household Bleach solution you purchase in the store for use with laundry etc. has 5.25% Available Chlorine (5.25% AC) In a laboratory, when talking about sterilizing seeds in a 10% bleach solution, one refers to that store bought bleach (sodium hypochlorite) watered down to 10% of its strength, which results in a 0.525% AC solution. To make the sterilizing solution, take 9 parts of distilled water and add 1 part of the store bought 5.25% AC sodium hypochlorite to it.. Less confusing is to express sterilizing solutions in %AC. In terms of available chlorine we say the sodium hypochlorite solution we made and use for sterilizing seeds has about 0.5% AC (rounded off, one half percent AC ) One must always be aware, when dealing with very contaminated seeds, that increasing the duration of sterilizing times may at some point kill the embryo before contaminants are killed. (not desirable) In my lab we soak seeds first in a sugar solution to germinate the contaminants so they are easier to kill. We use a calcium hypochlorite solution of 0.3% AC and sterilize orchid seeds for 15 minutes. Peter _______________________________________________ the OrchidGuide Digest (OGD) orchids@orchidguide.com http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
