[Plant-biology] Re: Garlic and Green Peas

bae at cs.toronto.no-uce.edu bae at cs.toronto.no-uce.edu
Wed Jan 4 09:58:34 EST 2006

In article <15633-43B88812-743 at storefull-3138.bay.webtv.net>,
~Sea~ <seatick at webtv.net> wrote:
>Hello all, hope you can help me with a research project I am working on.
>It concerns the effect that garlic has on the growth of green peas. I
>have found that peas that are watered with a solution containing garlic
>are stunted, but I have not been able to locate the reason for this.
>What is in the garlic, or what is the causative agent, that stunts the
>growth of the peas?? I have searched high and low, on the 'net and in
>books but I have not been able to find out how or why the garlic affects
>the growth of the peas like it does. Anyone have any ideas? Thanks so
>much for any help with this.

Note: much of this is pure handwaving, and you'll have to do more
research to see what, if anything, is relevant.

Garlic contains antifungal and antibacterial compounds.  Conceivably
they are interfering with the ability of the peas to take up nitrogen
fixing bacteria.  Examine the roots of both groups to see if the
controls are better nodulated.

Other theories -- the garlic is modifying the microbial composition of
the soil, either by inhibiting favorable microbes or by providing
nutrition for unfavorable ones which are damaging the roots.  Rotting
of fresh organic material (the garlic) is reducing soil oxygen and/or
generating toxic hydrogen sulfide.  Something else in the garlic or the
solution you are using is toxic -- you aren't using detergent in it,
are you?  Is the control getting the same solution without the garlic?
Try a control that gets a solution with the same amount of non-garlic,
e.g. potato, too.  Try groups with a series of solutions containing
more and less garlic with the rest fo the composition constant to see
if the effect varies with garlic content.

Something else in the environment is different for the two groups.  In
a garden, there may be substantial differences between small patches of
soil.  Repeat with as many groups as possible in different parts of the
garden.  In a greenhouse, or under lights, there may be substantial
differences in temperature and light intensity over small distances.
Measure these repeatedly at different times of day and season, and
repeat your experiments with the plants in different positions.  Soil
in pots may be changing in the two groups -- the garlic group may be
getting dense and waterlogged due to the added organic matter. Potted
plants react dramatically to problems in the soil.  Wet soil, rich in
organics, may also cause a proliferation of fungus gnat maggots, which
can damage roots.

I realize this gives you a lot of work to do, but I hope it helps.  Let
us know what you find out.

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