Hi all,
They will take as much light as you can find, any damage is likely to be heat related. Yes definitely root hairs, for the reason mentioned, something that was well known, but only demonstrated scientifically relatively recently actually using
Limnobium:
Gilroy, S. & Jones, D. (2000)
"Through form to function: root hair development and nutrient uptake "
Trends in Plant Science 5:2 pp 56-60
Abstract:
Root hairs project from the surface of the root to aid nutrient and water uptake and to anchor the plant in the soil. Their formation involves the precise control of cell fate and localized cell growth. We are now beginning to unravel the complexities of the molecular interactions that underlie this developmental regulation. In addition, after years of speculation, nutrient transport by root hairs has been demonstrated clearly at the physiological and molecular level, with evidence for root hairs being intense sites of H+-ATPase activity and involved in the uptake of Ca2+, K+, NH4+, NO3−, Mn2+, Zn2+, Cl− and H2PO4−.
Here's their "Limnobium" root hair figure:
We have used
Lemna in the past to measure their response to the level of nutrients in the water column (from the "The Charms of Duckweed"
http://www.mobot.org/jwcross/duckweed/duckweed.htm, but I've found that both Nile Cabbage (
Pistia) and Amazon Frogbit (
Limnobium) shows a similar, but much more impressive, response to the level of nutrients in the water column, with low nutrient levels producing relatively smaller leaf rosettes, but fantastic large and "frilly" roots.
cheers Darrel