does anything come OUT of the roots ?

[Mr Greenjeans]

GpsFrontier,

Thanks for your response and knowledge. I suspected there was some form of discarge from the root system. I'm interested in learning more about when this occurs.

I would assume nutrients go into the roots and throughout the plant during the daytime, in natural conditions. This is when the stem, branches and leaves are warmed by the sun. The soil is relatively cool. At night, after the sun goes down and the stem, branches and leaves cool, does the flow through the plant vessels actually reverse ? I'm thinking the flow must reverse, in order for anything to come OUT of the roots. But if the flow reverses, is this when it happens ? Do you or anyone else know about this.

I am not particularly interested in knowing what exactly is in the exudate (thank you GpsFrontier for that word). I'm thinking along the lines of totally dispensing with the nutrient solution at regular intervals, perhaps daily. I realize that replacing the solution every day with all new nutrients may not make economic sense. I'm considering that it would however, help improve plant vitality in certain or many species.