Nutrient Transport from Root to Leaf

ceg4048

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Mar 21, 2005
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Mr. Barr,
I've read where terrestial plants and emersed plants use the mechanism of capillary action to pull water from roots to leaves. In one article (it may have been on the Tropica website) it was explained that as water evaporates from the leaf surface through exit pores at each "capillary" (there was probably a more scientic term) the vapor action pulled minute quantities of water up to fill the space voided by the evaporated water in the tube. By this action nutrients from the substrate is slowly "wicked" up to the leaves. I've always found it incredilble how tall trees pull tons of water from beneath the ground to distribute it several stories high without any moving parts.

In the case of submerged plants this mechanism clearly cannot function so could you offer any insights as to how aquatic plants move water and nutrients from their roots to their leaves?

This also begs the question of how the plant moves bouyant gases such as Oxygen from leaf downward to the roots?

Cheers,
 

Gill Man

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Feb 10, 2005
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Re: Nutrient Transport from Root to Leaf

There's more to it than just the "wicking" action. There's also the unique property of water and that's it's surface tension, which is what helps it attain great heights in trees.

Submerged plants probably utilized simple diffusion to get molecules from areas of higher concentration of areas of lower concentration. I've noticed the substrate bubbling from time to time, but this may or may not be oxygen, but rather a byproduct of anaerobic activity.
 

Tom Barr

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Jan 23, 2005
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Re: Nutrient Transport from Root to Leaf

There are concentrational difference that can drive this and also in the aquatic environment, both leaves and roots have access to the water, so they have far less transport issues to begin with.

Phloem transport mechanism are very poorly understood even in terrrestrial plants. Munch's pressure flow hypothese is popular.
While transpiration brings some nutrients, it does not transport many things.

I'll post more later, got to finish some work here!

Regards,
Tom Barr