Gravity and agriculture

Hi all,

Does someone know how well plants go on micro-gravity environments? I know
that some experiments with plant growth were conducted in the space shuttle
in the eighties, but I know nothing about the results. My gut feeling is
that geotropism - the tendency of plants to grow upright, in order to
sustain their structure against gravity - would be completely screwed up,
but otherwise they would be somewhat normal in terms of nutrient and seed
production. (Vegetables in general are pretty amorphous organisms, when
compared to animals, and I think that the chance of things going awry in the
development of a plant in zero-g are correspondingly small.)

If that assumption is correct, then agricultural sectors in space colonies
could have a fairly small gravity (just enough to keep water in the
hydroponic tanks, and that sort of thing) thus minimizing structural costs.
In fact, for the case of a colony associated with an asteroid, the
agricultural sector could indeed be completely detached from the colony: it
could be a transparent pressure bubble built around the asteroid, with
plants growing close to its surface; the bubble could rotate in a 24-hour
cycle (regardless of the asteroid rotation) and be filled with nearly pure
C02. (One could argue that the gravity of an asteroid wouldn't be sufficient
even for keeping "water in the hydroponic tanks, ad that sort of thing".
Well, I don't have a final answer on that - experimentation only could give
it - but observations made on the surface of Eros show that boulders have
rolled to the bottom of the depressions of the asteroid even with its nearly
zero gravity. That is not so outlandish as it may seem at first: with 0.001
g, like in Eros, you would be able to actually *see* a stone falling after
releasing it - in the first second, it would be half centimetre far from
your hand, and then two centimetres in the next second, and so on... You
would have *clues* that things have some weight there.)

Lucio Coelho