Bad Soil Mix
rob_last at QMRELAY.MAIL.CORNELL.EDU
Wed Jun 2 17:33:05 EST 1993
The Boyce Thompson Institute
Subject Bad Soil Mix 6/2/93 4:12 PM
I know that some readers are going to read this posting with disbelief: 'Is he
kidding, he is having trouble propagating the easiest plant in the world to
grow?'. Unfortunately, we are having a recurrent problem of poor Arabidopsis
growth in WR Grace Redi Earth soil-less mix. We have used this product for
Arabidopsis at the Boyce Thompson Institute for four years now, usually with
very good results. Our plants are all grown under artificial lighting with
good-excellent temperature (20-22 C) and humidity (30-60% RH) control.
Here is a brief description of the syndrome: The seeds germinate in a normal
amount of time, but then the seedlings simply fail to thrive. True leaves
emerge but do not continue to expand past a few millimeters. These true leaves
are often light green in color and the cotyledons are sometimes anthocyanic.
It is not unusual to see plants with long hypocotyls. Often, the best looking
plants in an otherwise miserable group are found growing along the margin of
This recent episode began last month, and the syndrome is very similar to the
problem that we experienced last summer, also starting in early summer. This
is leading us to believe that whatever is going wrong might be related to the
season (perhaps the conditions under which the soil product is/was stored).
One of the most frustrating aspects of this situation is that the vigor of the
plants often varies from pot to pot, or within areas of a pot. This means that
the results of any experiments that we perform to try to understand the nature
of the problem are uninterpretable. Our best guess is that there might be
something growing in the soil that is toxic or is producing a toxin or growth
regulator, but we have many other theories that are equally reasonable.
Has anyone else experienced this type of a problem with this particular brand
of potting mix, or any other soil type? If so, do you have a solution? Please
respond even if you have not figured out how to solve the problem because there
will be strength in numbers when I call the tech support person at W.R. Grace.
I will summarize any responses soon.
Boyce Thompson Institute
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