Re: [APD] Re: Begging limitless questions

["S. Hieber" <shieber at yahoo_com>]

Well, this is one of the more interesteing threads I've
seen in a long time -- and I find nearly all of the threads
interesting!

An interesting turnabout on viewing general techniques:
deciding how to limit plant growth and which appearances
(nutrient deficiencies (including CO2 as one of the
possible nutirents)?, light deficiency) are acceptable.


Scott H.
--- Roger Miller <roger at spinn_net> wrote:
> On Tuesday 16 September 2003 21:11, Scott H. wrote:
> 
> > Yep, same goes for lighting too, and the rest, right? 
> So
> > why must there be a deficiency?
> 
> Some years ago in this post
> 
>
http://fins.actwin.com/aquatic-plants/month.9603/msg00541.html
> 
> Dave Heubert offered the tidbit that under ideal
> conditions fast growing 
> aquatic plants are capable of doubling their mass every
> 4-6 days.  Personally 
> I may have seen plants grow that fast briefly, but I've
> never seen any plant 
> sustain that kind of growth.  Most of our aquarium plants
> grow much more 
> slowly than that and it's a good thing.  Personally I
> wouldn't want to remove 
> 1/2 ot 2/3 of the plant mass in my aquarium every week
> just to maintain the 
> status quo.
> 
> Perhaps in some cases the growth rate is limited by the
> genetic makeup of the 
> plant.  I doubt that accounts for very many limitations
> because if it did 
> then we would never see variations in the growth rate. 
> The growth rate would 
> be a predetermined constant set by the plant's genetic
> code.
> 
> I theorize that almost any healthy-looking plant we see
> in our aquariums has 
> its growth limited by light.  In some cases perhaps the
> CO2 supply is the  
> limiting factor.  I maintain that theory plainly and
> simply because every 
> nutrient shortage has a disease-like deficiency symptom. 
> I don't think a 
> gardener can limit plant growth with nutrients without
> eventually seeing 
> those symptoms.
> 
> I think this also goes to why George B. protests so about
> the recent trend of 
> recommending high light in aquariums.  High light levels
> do little more than 
> lift the limit on growth rates, force greater demands on
> CO2 and nutrient 
> levels and increase the likelihood that nutrient-related
> problems will set 
> in.  Why go out of your way to invite problems when there
> is so little to be 
> gained?
> 
> The question about how a light-limited plant looks may
> have a simple answer; 
> it looks healthy and well-nourished. There are obviously
> lows at which this 
> is no longer true -- where the light is too low for
> plants to grow.  That 
> point varies from species to species.  A healthy-looking
> aquarium always 
> contains an assemblage of plants that can grow well
> within whatever light 
> limits the aquarium imposes.
> 
> Much of this might also be said about plants with growth
> limited by CO2.  
> Light and CO2 are so closely linked that their effects
> can be difficult to 
> distinguish.
> 
> 
> Roger Miller


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