When rice is grown in anaerobic soil, it develops barrier to radial oxygen from root to soil. This barrier is mainly suberin in the outer layers of root. Is it logical that this barrier does not limit root hydraulic conductivity (to water)?
Dear Dr. Abogadallah,
The mechanism is not completely clear, but it looks like pore size in suberin polymer layer may play a role. Simplified explanation is that oxygen molecule is a bit bigger, than water molecule and so, water can pass the barrier, whereas oxygen cannot. Some information you can find in the attachment on page 2.
Sincerely,
Konstantin.
Kindly go through paper of PC RAM submergence tolerances where in descrition of oxygen/carbon dioxide molecules under normal and flash floods described. THe basis is diffusion coefficients of most of the gaseous molecules dependent on their solubility rather than in free form. Whether the roots are in anaerobic or aerobic root zone is not very important when it comes to gaseous oxygen since the passage of oxygen within the roots is in soulble forms rather than free form. one of the best paper I have ever read.
Thank you Konstantin and Voleti
If suberin does not limit water permeation through the exodermis and outer layers of root, why does the endoermis limit the passage of water (and solutes) by having casparian strips (which are mainly suberin)?
Dear Dr. Abogadallah,
Suberin deposition in the endodermis is always thicker than in exodermis. That may be the reason for more effective restriction of water passage through the endodermal cell layer.
DEAR GABER
The attached content has some relevent information which might be useful to your good self.
Ann Bot. 2005 Sep; 96(4): 625–638.Published online 2005 Aug 10. doi: 10.1093/aob/mci215PMCID: PMC4247030
Rice: Sulfide-induced Barriers to Root Radial Oxygen Loss, Fe2+ and Water Uptake, and Lateral Root Emergence
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