🚀 go-pugleaf

G'day mate,

Thanks for this response. I wasn't imagining things after all. 8-)

I'm forwarding this to aus.science where the question was 
originally posed.

In article <2004Aug2.105307.23879@jarvis.cs.toronto.edu>, 
bae@cs.toronto.no-uce.edu.yyz wrote:
>In article <2n4akrFsa6p6U1@uni-berlin.de>,
>Phred <ppnerkDELETETHIS@yahoo.com> wrote:
>>In article <2UUOc.25560$K53.12853@news-server.bigpond.net.au>, 
>>"Don H" <donlhumphries@bigpond.com> wrote:
>>>Tropism ("turning") in plants is their orientation when growing: upwards for
>>>stems, and downwards for roots.  The upwards trend can be attributed to an
>>>attraction to light (phototropism), but downwards - due to gravity?
>>
>>Plant shoots also respond to gravity.  They grow "up" in the dark when 
>>seeds germinate buried in soil.  I also have a vague recollection of 
>>experiments done decades ago  where plants growing in rotating 
>>chambers lost the effect of geotropism and grew in "random" 
>>directions.
>>
>>Maybe someone in sci.bio.botany will put me straight on this.
>
>Wow, what a blast from the past!

Just the other day really.  ;-)

>In 1968, I was at Argonne National Labs near Chicago as an undergrad
>summer student.  On a tour, we were shown the place where some of these
>experiments were in progress.  It was a concrete blockhouse, and you
>had to go through a series of doors to make sure no light got in.
>There was an extremely faint green safelight to turn on, and once your
>eyes adapted to the very near total darkness, you could see the three
>"gravitational compensators" going through a slow synchronized dance
>controlled by IIRC a PDP-6 minicomputer.
>
>The seeds were placed in containers of vermiculite which were moved in
>three dimensions in a pattern that ensured that the gravitational
>vector was never constant long enough for the plants to "perceive" it.
>They did, indeed, send their shoots and roots in random directions.  I
>remember that there was a problem in that seeds which rooted up into
>the air portion of the chambers tended to dry out and die, skewing the
>results, and they'd had to go to some trouble to deal with this.
>
>IIRC, the mechanism of geotropism as understood at the time had to do
>with starch granules settling towards the bottom of the cells.  I don't
>know what the current belief is.  It's an old problem - Darwin wrote
>about it.
>
>The research at Argonne was funded by NASA.  In those days before the
>Vietnam War clobbered so much research funding, it looked like the
>growth of plants in microgravity might become of considerable practical
>interest in the not-too-distant future.  So it goes.

Cheers, Phred.

-- 
ppnerkDELETE@THISyahoo.com.INVALID