"Loki" wrote:
The roots grow down - away from light and reacting to gravity,
water etc.

I think roots grow in a generalized direction out, with gravity
maintaining a constant pull so there is a slight downward pull
to their outward growth. Most seems to follow along the same
guidelines that electricity follows... meaning they take the path
of least resistance. Trees seem to have one main trunk that
goes down and branches sprawling in all directions in the
ground, and this would make sense, because resistance is
low to start and as the main trunk dives deeper, the resistance
increases, so the branches that sprawl outwards underneath
get more water being near the surface, so there is a slight
"hunger" to stay near the surface. An increase in the amount
of area by the branches spreading out in the ground provides
a mechanism to support the main trunk above the ground and
provides a greater surface area to drink from.

One thing to keep in mind about this as well is that it's like
diving, and the deeper you dive, the greater the pressure
is on you. All that water above you has a weight and that
weight is expressed as a pressure, psi (pounds per square
inch). There is a limit to depth that you can dive, I don't
know it is off the top of my head, because once you reach
that depth, the pressure becomes so great that you could
die from the compression. Submarines have a maximum
depth they can travel, each type of fish have a maximum
depth, and I imagine the same applies to the roots of trees.

I let some pigweed grow here and was interested in it's
rooting. When I pulled it from the ground, the main trunk
dove straight down. I let it grow to about 5 feet in height
before I pulled it. The main root that dove straight down
was the strongest and it only dove about a 16 inches at
most. The main branches that came off it sprawled in all
directions about 12 inches in every direction. I imagine the
sprawl was actually greater, because those branches were
a lot thinner than the main trunk and they decreased in size
and strength farther out. They broke at the outer lengths.
Those branches in the ground are what provided the
support for the height.

I think the factors that control rooting a
1) There is a slight pull from gravity,
2) Thirst for water means there is a sprawl away from the
main stem,
3) Rain being a source of water provides the most effect (in
the beginning) at the surface and that effect decreases the
deeper you get, UNLESS you have an underground supply
of water. In the latter case, it will be water plants that would
flourish.
4) As far as tomatoes go, they seem to love a RICH WET
soil and they seem to love a bottom fed water supply. I'm
having great success with four plants in a clay pot (1 quart),
which I keep in a bowl and I keep the bowl filled with
water. It's kept in the shade of a tree it's got some stakes
for support and fence nearby that I'm hanging the longer
vines upon.

I don't know whats right or what's wrong, but the tomatoes
seem to be very happy.

With tomatoes being set upside down, there is still that pull
down on their branches in the dirt. Once they hit a wall, the
roots would tend to grow away from the wall or along the
traveling in the path of least resistance. If the least resistance
happens to be up, the growth should grow up. I think I
can almost argue that light has nothing to do with root
growth, other than it's light that does whatever it does with
chlorophyl or whatever it is. The nutrients are drawn from
the soil and light does something with chlorophyl. Thus the
greenery is up top where the light is, and I don't quite have
a grasp of what actually makes the roots work, some kind
of energy created by a thirst for water and the leaves up top.

I don't know how much of what I said is 100% fact. It's all
just my own thoughts on root growth. Don't take it at face
value. I found it interesting and thought I'd leave some of
my own thoughts on it.

--
Jim Carlock
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