Redfield ratio for aquatic plants

[Thomas Barr <tcbiii at earthlink_net>]

Someone asked about a Redfield type ratio for aquatic plants(Garten 1976).
Well here it is and no surprise here:
N:P=> 8 to 10:1

Algae? 14:1(Redfield 1958)

PO4 limitation hurts the non vascular, vascular and non aquatics based on
this ratio more than the algae based on limitation theory if it is all in
the water column.

The ratio remains surprisingly constant when plants receive this ratio even
if the nutrients or light limits growth even(for plants).(Ingestad & Agren
1988)

Chapin (1980) also has some interesting patterns of the order of how a plant
reacts when a nutrient supply declines. 1) a decrease in vacuolar reserves
with little effect on growth,
 2) continued reduction in tissue nutrient concentrations,especially in
older leaves and stems, reduced rates of leaf growth and photosynthesis,
increased non structural carbohydrate levels, old leaves falling off,
increased root mass ratio, more root absorption capacity.
3) Greatly reduced photosynthesis an nutrient absorption, dormancy or death
of the meristems/active growing regions.

Plants will also adapt and get use to low or limited tanks/conditions.
Food for thought.
Regards, '
Tom Barr