[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Experimental Design: Aquatic Plants
- To: Aquatic-Plants at actwin_com
- Subject: Re: Experimental Design: Aquatic Plants
- From: Paul Krombholz <krombhol at teclink_net>
- Date: Tue, 10 Sep 2002 22:12:47 -0500
- In-reply-to: <200209100748.g8A7m3g09018 at acme_actwin.com>
- References: <200209100748.g8A7m3g09018 at acme_actwin.com>
>
There are a lot of questions about dosing levels for nutrients such
as nitrate, phosphate, and potassium. How high should one maintain
levels in the aquarium? Tissue analysis of the plants would be a
good way to see how much of the nutrients the plants are actually
getting and whether or not they are anywhere near to being deficient.
Plants are capable of considerable luxury consumption for nitrogen
and phosphorus, and I am pretty sure for potassium, too. This means
that they can store higher concentrations of the nutrient in their
tissues than they need for maximum growth---that is, growth
unrestricted by a need for the nutrient. For nitrogen aquatic plants
have a luxury consumption range from about 1.5% to a little over 4%
(%N of dry weight). For phosphorus, the luxury consumption range is
from around 0.15% all the way to a little over 0.7% of dry weight. I
don't know what the values are for potassium, but they can be found
in the literature. If you pull plants out of the aquarium and get
values at the low end of the luxury consumption range, then more
dosing is called for. Highly N-deficient aquatic plants go down to
about 0.7% N or a little less, and Highly P-deficient plants go down
to between 08% and 0.1% P. The point of all this is that you can
pull a plant out of an aquarium or a lake, analyze it, and get a good
idea of how much of the nutrient it is getting and whether it is
deficient, near deficiency, or way off in the luxury consumption
range so that it has enough stored to allow doubling or tripling its
weight.
So.......If you have access to equipment that can be used for tissue
analysis, you could answer a lot of levels about dosing levels.
There are lots of questions that can be asked. One that I would
particularly like to find out is: Does low or moderate level iron
deficiency interfere with nitrogen and or potassium uptake? I've got
a suspicion it does.
--
Paul Krombholz in dried-out central Mississippi.