ciratac

This is a request for some information from those of you in the know.
It doesn't quite fit the criteria of the theories forum, as it's not
new, but I suspect the discussion could get rather advanced and technical
so I put it here.

Over here is a discussion about some of the issues in revegging a flowered
plant. I'm not interested here in discussing the merits of revegging,
I'm just curious to hear a discussion/lecture on the physiology of
the reveg process.

We know that a hormone change is induced by a photoperiod including
12 or more hours of uninterrupted darkness, and that this change
causes flowering.

After flowering, we may reduce the dark period to as little as zero,
and the plant reverts to vegetative growth.

Can the plant revert completely, as if it had never flowered? Or are
there structural changes induced by flowering which can't be fully
reversed? Surely the plant's genetic coding doesn't change, so it
retains the potential to develop exactly as it did before flowering. But
do the flowering hormones cause it to grow in such a way that it really
can't go back completely? Why?

Since we're making an annual flowering plant do something that nature
didn't intend, it's hard extrapolate. But lots of things that nature
didn't intend are done routinely, and successfully.

I for one would like to learm more detail about the mechanisms
involved. If you have expert knowledge about flowering plant physiology,
please jump in.

-ciratac-

Delta

Ethylene is autocatylitic. Once it starts, it doesn't stop.

my $.02

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JoseHempSeed

huh?

organic

Where's bgetting when you need him? This q would have been right up his alley.

Delta, what kind of changes does ethylene cause to the plant structure?

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lurkapup

is that saying that even when they're reveging plants are actually still flowering (kinda) cause thats well freaky!!

like Im thinking that they are still producing the flowering chemicals/hormones .... so whats the effects of having these running during vegetative cycle .. and whats the effect on flowering if the plants been producing these for months already .. does it get tired? or can it build (like a muscle? )

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KRS_ONE

But from my observations the cycle with the plant is much the same as the aging process with animals/humans.

As a seedling the chemical process within the plant are geared for certain growth patterns.

As the plant develops the balances/ratios change as the plant requires different growth patterns and more/less of the various hormones/nutrients.

When the lights cause the change to flowering the very cells themselves are changed to produce/collect the necessary hormones/chemicals used for flower production.

When senescence begins the plant is at the end of its cycle. Being an annual that is naturally propegated through seeds we can resonably say that the natural order of the plant holds no option for reverting back to any earlier stage.

Just as humans "age" thru different chemical processes, or lack there of in most cases, the plant "thinks" that once it is done it is done. By forcing it to go back into vegetative cycle we are in essence creating a new, IMO unnatural, cycle for the plant to utilize.

I have done several reveg experiments. From my results I have concluded that the time and energy are best used for a new plant.

I have purposely not spoken of Auxins and Cytokinins, Giberrilins, and the rest of these hormones and chemical process as my understanding of them is still lacking in my opinion.

Bgetting or Delta9420 or THChemist would all be more adept at explaining these factors quantitatively.

K

ciratac

Okay, let's start with ethylene. I did a little reading (just enough to be
dangerous ) about its role in plants. Here's what I think I've learned.

Plant tissues produce ethylene at low levels throughout life.
During ripening of flowers or fruits, ethylene production increases,
causing an autocatalytic response: higher levels of ethylene cause higher
levels of ethylene production. The higher and higher levels of ethylene
lead to senescence, in which the cell walls in the fruit or flower
loosen, eventually leading to rotting. With fruits, they fall off
and the seed is left behind when they rot or are eaten.

(apparently this is why you can put unripe fruit in a paper bag
and it will ripen faster: you retain the ethylene, which is a gas,
raising the level, causing it to be produced faster, speeding
ripening)

But in a revegged pot plant, we avoid/delay senescence: it doesn't
rot, and we can successfully regrow it and reflower it (albeit
with reduced yield). So we must be somehow turning down the rate
of ethylene production, since the plant doesn't finish its life cycle,
but continues growing. Maybe it's the removal of most of the buds that
causes this?

I haven't been able to find anything about the role of ethylene in
the transition from vegetative growth to flowering. Clearly
there's some signal which causes vegetative apices to convert to floral
apices, and this is what must be reversed.


My head hurts from websurfing through scientific papers that I barely
understand.

JoseHempSeed

That's very interesting, ciratac. thanks.

it sounds like the signal is changes of the light cycle.

ciratac

> it sounds like the signal is changes of the light cycle.

Oops, I didn't say clearly enough what I meant. The signal I was talking
about is the biochemical signal (hormone) that is initiated by the change
in light cycle.

I read in one of those papers that the signal is generated by the leaves,
and then transported to the growing tips, which causes them to transform
themselves into flowering tips.

Ethylene production is controlled by another process, which is
amplified during flowering/fruiting, especially at the end.

Man, I'm in over my head here.

On another note, the fact that the flowering hormone(s) might be
generated in the leaves certainly bears on the "removal of fan
leaves" debate.

OzGrowa

Well said ciratac, great job there and pretty correct from my reading. The times taken for a plant to revert back to the vegitative stage can be up to 2 months in my experiences, this shows the level of ethylene is upregulated to massive levels during flowering and that they can gradually drop off when the plants are given a 24 hr cycle or similar but this process is gradual. Even in the presence of 8.5K + light levels I have noticed the same length of time for the change back and baring in mind the flowering period duration of 8 weeks, its no wonder!

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