Pistia root length and nutrients

[IvanF]

I recently introduced a variety of floating plants to my new 310L low-tech set-up (thanks dw1305) in order to determine which species take to my conditions.

What this means is that for the past week, I have a dense mass of floating plants across the less turbulent 40% of my surface, directly under an LED tile - all of which seem to be doing pretty well thus far - Limnobium (flowering), Salvinia, Pistia and Ceratopteris (rampant).

As expected, the Pistia is sending out long roots of a variety of lengths (which look great). Whilst the average root length is probably 4" one particular Pistia has rapidly shot out roots approximately 12" in less than a week since introduction.

I'm curious whether the variable root length of the Pistia tells me anything about my tank/nutrient levels or distribution? I'm dosing with TNC Complete on a weekly basis, and all plants within the tank look pretty healthy and are developing healthy new growth - so I guess that on the whole my nutrient levels are decent. Possibly a sign of intense and sudden localised competition in a new environment?

 

[Andy D]

I believe it is down to nutrient demand but this is my theory and others may well actually know.

When my LED bar was about 5" from the surface the Pistia stayed relatively small - about 1-2" across. The roots were also no more than about 2-3" long.

When I dropped the LED bar to about an inch from the surface the roots did get longer. I put this down to the plant requiring more nutrients as the light intensity had increased. This was also followed by a massive growth spurt with some of the plants geting to 9" or 10" across.

 

[dw1305]

Hi all,

as expected, the Pistia is sending out long roots of a variety of lengths (which look great). Whilst the average root length is probably 4" one particular Pistia has rapidly shot out roots approximately 12" in less than a week since introduction. I'm curious whether the variable root length of the Pistia tells me anything about my tank/nutrient levels or distribution?

It is definitely a nutrient effect, but it is also to do with the time of the year.

All the Pistia plants I've grown have shrunk back to smaller rosettes of flat leaves for the winter, followed by a rapid bulking up in the spring and a change in morphology to a more upright leaf rosette. While the new leaves are growing the plant will show root extension, although root mass will increase at a much slower rate than for the aerial biomass.

Pistia shows a linear growth response to nutrients up to really high levels. This is one reason it has been extensively used for phytoremediation in warmer areas.

cheers Darrel

 

[Andy D]

Crikey! I thought mine were big.