Date: Wed, 08 Jan 1997 18:52:00 -0500
From: Kelly Zytaruk <kingfish!zytaruk@sx.com>
Subject: [11922] Seed germination mediums

With the recent interest in Calcium hypochlorite versus Sodium
hypochlorite as a sterilizing agent for orchid seeds, I decided to do
a couple of tests of my own.  I have done some experiments where I
sterilize some seeds in both Calcium hypochlorite and Sodium
hypochlorite.  I have also included the results of using different
mediums for germination.  I thought that some of the flaskers out
there may find this of value.  This is a lengthy posting so if you are
not interested in flasking, you can skip to the next message.

I have tested with two different mediums (G&B Mother flask medium V,
and Sigma Phytamax P0931 mixed at 2/3 strength).  This gives four
possible combinations as follows;

CaGB - Sterilized with Calcium hypochlorite and sown on G&B medium
NaGB - Sterilized with Sodium hypochlorite and sown on G&B medium
CaSi - Sterilized with Calcium hypochlorite and sown on Sigma P0931
NaSi - Sterilized with Sodium hypochlorite and sown on Sigma P0931

Actually I have also tested with a third medium, Knudson C from Sigma.
The results from the Knudson C were so poor in comparison to the other
two that I stopped using it and didn't bother to include it in the
results.

Calcium hypochlorite was mixed as per Fred Bergmans instructions and
Sodium hypochlorite was Javex (5% Sodium hypochlorite) mixed with 19
parts water to give 0.25% (5% Javex in water). Note that most will
recommend 10% Javex in water.  I feel that this strength is not
needed.  Sterilization time for Calcium hypochlorite was 6 minutes and
sterilization time for Sodium hypochlorite was 5 minutes.  Both with
constant agitation.

When number of days is given, it is the number of days from sowing
until I have noticed some greening up of the seeds.  I don't know if
this is the proper way to define germination or not, but if I have
green swollen seeds, I know that I will always have protocorms (with a
minor exception - see notes on Phal violacea).

Where a possible combination is missing, I didn't feel the urge to test with
that combination.

So here it goes;

Sederia japonica - 21 days
    NaGB: good germination, average growth
    NaSi: good germination, growth twice the size of NaGB
    CaSi: good germination, average growth, similar to NaGB

Spathiglottis plicata - 21 days
    NaGB: good germination, average growth
    NaSi: good germination, growth 25% better than NaGB

Phal violacea -
    Seed was originally sown on full strength P9031 and G&B.
    Both mediums caused the protocorms to swell and promptly die.
    I am trying again with 2/3 strength P9031, no results yet.

Phal tetraspis - 21 days
    NaSi: 100% germination
    CaSi: 50% germination, growth about the same as NaSi

Houlettia lowiana - same as Phal violacea
Laceana bicolor - same as Phal violacea

Epidendrum Locha - 21 days
    NaGB: Good germination, growth approx 25% bigger than NaSi
    NaSi: Not as good as NaGB

Epidendrum grande - 11 days
    NaGB: good germination
    NaSi: All flasks contaminated

Tricopilia elegans - 28 days
    NaGB: Good germination, growth slightly better than NaSi
    NaSi: good germination

Oncidium eurycline -
    NaGB: 14 days, Good germination, growth twice the size of NaSi
    NaSi: 14 days, good germination
    CaGB: 21 days, Good germination, growth twice the size of CaSi, a little
behind NaGB
    CaSi: 21 days, good germination

Phal faciata -
    No germination with any combination after 60 days

Laelia anceps var williamsiana - 49 days
    NaGB: Approx 10% germination
    NaSi: Almost 100% germination, growth slightly larger than NaGB
    CaGB: Approx 10% germination, growth 1/3 of NaSi
    CaSi: Approx 10% germination, growth 1/3 of NaSi

Phal schilleriana - 21 days
    NaSi: All flasks contaminated
    CaSi: Good germination

Oncidium staceyi -
    NaGB: Average germination
    NaSi: Better germination than NaGB, growth approx 25% bigger than NaGB

Osmoglossum pulchelum -
    NaGB: excellent germination
    NaSi: excellent germination, growth slightly larger than NaGB

Cattleya maxima - 14 days
    NaGB:  excellent germination

As you can see, no single combination is best for all species.  I will
continue to use both mediums for seed sowing. I hope that someone
finds this information useful.  If any other flaskers out there have
any notes or experience to share, I would love to hear of it.  And as
usual, if anyone out there has excess seed that they are willing to
share, I would love to receive some of it.

Kelly
Email: zytaruk@sx.com