Repeating Decimal said:

Thanks for the information. The trouble with the rec.garden.hydroponics
newsgroup is that it was never very active. If it were, I would be more
upset to not be able to get it. In any event, I cross posted because I
thought it would be of interest to both groups.

That is probably because rec.garden.hydroponics was on a list of bogus
newsgroups -- ones that did not go through the proper charter proposal,
RFD and vote. This means the big news servers don't carry it. And I
don't recall seeing a RFD (request for discussion) in the time since I last
perused a list of bogus newsgroups. (It would be easier to start an alt.*
group on the subject; rec.* groups have to reach a threshold of interest
before they can be authorised, so not enough 'yes' votes and the proposed
group will fail, even if 'yes' votes outnumber 'no' votes.)

That is, I would think that any gardener would be interested in the
chemicals transported across root surfaces.

Well, some people think one of the reasons for crop rotation is to avoid
an accumulation of root exudates by any specific crop.

Plants do exude compounds from their roots. These root exudates can be
alellopathic (toxic to other plants) or can be involved in the symbiotic
relationship with mycorrhizal fungi or other soil microorganisms. These
root exudates may be what makes some plants good companions in the
garden while other pairings are disadvantageous.

Yes, they do exist and yes, it might be best to purge them from a hydroponics
system at intervals, especially if you are growing a variety of different plants.

--
Pat in Plymouth MI

Any technology distinguishable from magic is insufficiently advanced.
(attributed to Don Marti)