Growth rate in plants/ water

[ascalon]

Does the rate of hydration, or absorbtion and assimilation of water into plant cells play a large role in the growth rate of plants?

[Turtle]

Originally Posted by ascalon

Does the rate of hydration, or absorbtion and assimilation of water into plant cells play a large role in the growth rate of plants?

At the very least, the rate of loss does play a role. For example the waxy coverings of plants allows them to slow their growth and still live during drought conditions.
As to gaining some advantage by speeding hydration, I see it only as potentially advantageous for restoring wilted plants. I suspect an experiment is required wherin all else is kept equal save the surface tension of the water. (I read that in from your other thread.)

[hallenrm]

The large plants that I am aware of, like the peepul or bargad tree have deep roots which give them easy access to underground water. Similarly the Eucalyptus trees are known for there fast growth, and it is very well known that they grow best in waterlogged land. But, I am not aware of any such large plants that grow in water.

But, then the question is about the rate of hydration, that is, how fast do the roots of a plant absorb/assimilate water, and not about how much water is available to them, I really do not have any straight answer, and would like to know better, that's the reason of my posting!

[moo]

Might check out this article in the Journal of Experimental Botany.

http://jxb.oxfordjournals.org/cgi/co...ll/54/392/2479

Excerpt: "The steeper field drove more water into the elongating cells, and their growth rate increased."

moo

[Ganoderma]

This reminds me of cacti. I tried this with cacti growing them under 24 hour light and relativly high moisture at lower temps (21-24)c. They grew incredibly fast, but i guess that would also be due to increased lighting. I have also had some grafted cacti split due to growing speen i think. When a slow grower is placed on a fast grower they grew so fast their skin split, this i would assume is because of increased water.

Sorry if its a little off topic, but i would think its due to far too much water intake.

[gribbon]

Try researching the affects of Cytoknins, particularly Adenin cytokinins, such as Auxin, Kinetin, Zeatin and Benzyl Adenine etc....these play a big role in the development of plants, although they do tend to inhibit root growth.

[vanamoinen1]

w/re: to rates of hydration--(and maybe this is a different thread), my question goes to the method of water uptake--is it brought up through the roots by passive means--e.g. capillary action or do plants have an active method by which to take up water? And if by an active method, what are the specific proteins involved in the mechanisms/apparatuses which do the work (i'd assume that some protein capable of inducing movement like a form of plant peristalsis would be involved)?

[Essay]

vanamoinen1,
I think it is just basically capillary action.
But I bet that's enhanced by a lot of biologically engineered nanostructures, as well as metabolic management of osmotic gradients.

p.s. ...but not large scale pumping of fluid--as with peristalsis.

[vanamoinen1]

Essay--thank you! I think you're on the money. Quick googling did produce an interesting hit: M. B. Kirkham, Kansas State University, Department of Agronomy-KSU, "Plant Water Uptake: Current Knowledge and a Look Ahead", which appears to indicates:
"That is, water moves passively through the roots in response to a water potential gradient set up by transpiration."

He also notes continue study of "aquaporins" which are a class of water channel proteins that have been found in nearly all living organisms. He also indicates that roots are capable of reverse flow--I suppose again, in response to a water potential gradient.

Thanks again!

[Essay]

Originally Posted by vanamoinen1

He also notes continue study of "aquaporins" which are a class of water channel proteins that have been found in nearly all living organisms. !

very cool stuff

Great find! Thanks, ...until you can post links:

Plant Water Uptake: Current Knowledge and a Look Ahead.

..and it looks as if you can get a video of a presentation from a Nov. 2006 symposium at this site:
Session: Symposium--Understanding Plant Water Uptake
with the video link at "11:30am," 81-8; ...the "green dot" link.
You mentioned transpiration--which is of course critical to the overall osmotic gradient.

The leaves do regulate transpiration rates by opening and closing their stomata--pores into/out of the leaves--used for gas/vapor, etc. exchange.
So in that sense, plants do have a fairly macroscopic mechanism (relative to molecular mechanisms) to help regulate water uptake. ...Not quite like peristalsis, butt more like a sphincter.