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Re: Folding Leaves

I asked:
>> Is there any benefit to matching photoperiod to the folding of plants'
>> leaves? Some of my plants (e.g., rotala wallichii) are folding up before
>> lights go off. Is this depriving the plants of anything, or does the folding
>> regulate the plants' biological processes regardless

Gilbert E. Martinez at martinez at gene_COM wrote:

> I dragged out my plant physiology textbook and re-read the chapter on
> biological clocks.  This Circadian rhythm we witness every night (photoperiod
> refers to flowering in response to day length) is in response to an internal
> clock mechanism, a photoreceptor pigment complex that is sensitive to light,
> notably, far-red and red light.
> When plants are exposed to an oscillating light environment, and they
> exhibit the same rhythm, they are said to be entrained to the
> environment.  Obviously my Cabomba has not been entrained to the light
> rhythm of my tank....
> Changing when your lights go on to coordinate with the circadian rhythm of
> your plants may benefit them as they may be ready to start metabolizing sooner
> than when your lights come on now, thereby giving them more time to
> photosynthesize.
> I hope this helps!

Yes it does, somewhat anyway. I'm still unsure if leaf folding before
darkness, whether due to circadian rhythm or nyctinasty or whatever, is
something to be concerned with. (BTW, I was using the term "photoperiod"
simply to refer to the length of exposure of the plant to light, not in
regard to flowering, which is of less interest to me than basic plant

I suppose my question is really twofold. First, how sensitive to daylength
(or nightlength if that's actually more accurate) are plants such r.
wallichii which fold their leaves? And second, for what reason (beyond the
biochemicalmechanisms themselves) do they fold their leaves? For example,
perhaps it simply lets them rest, or prevents "overmetabolism" or depletion
of stored nutrients, or allows the plant to begin certain metabolic
processes which are inhibited by light, etc. Or maybe it's purely a
circadian rhythm not enhancing or diminishing any actual metabolic activity.

Has anyone observed whether leaf folding before darkness had any noticeable
effects on the plant over time?

Dan Dixon