Re: [compost_tea] Exudates (was: Re: Brassicas and vam fungi)

From: Ted Peterson <ted.peterson_at_tcsn.net>
Date: Mon, 1 Nov 2004 11:07:49 -0800

So, is it the plant that makes the glycosinolate, or the bacteria? Or are =
the bacteria just using the glycosinolate made by the plant, and both the e=
xudate and bacteria have to be present in order for the inh8ibitory compoun=
d to be made? The latter seems to be the case.

But there are many other compounds that roots release that are not inhibito=
ry in of and by themselves. But, do those exudates select for bacterial or=
 fungal growth that will inhibit other organisms? Maybe. Do all of the ex=
udates made select for beenficial organisms which may inhibit the growth of=
 "bad guys". Hum......

I feel safest in saying, it could be the case, but it doesn't HAVE TO BE th=
e case. Some exudates may just be neutral,m and get used by neutral bacter=
ia or fungi. Or maybe the bacterial or fungal species that are supposed to=
 be present aren't, and then that exudate doesn't get used by the beneficia=
l organism(s), and inhibition doesn't occur.

Lots yet to know.

--
Elaine Ingham


Well, this is similar to my understanding. Yes, still a lot to know. I wa=
s curious in regards to your statements about Brassica exudates being suppr=
essive. I too think it is more closely tied with enzymatic action of the b=
acteria but have no data to substantiate that. Fungi are a different thing =
because they tend to be saporific. So if there is something in the plant th=
at inhibits decomposition by fungi, that would be interesting. Also, the b=
acteria involved with that interaction would be of interest. I know of the=
 use of Kale(s) as an antibacterial/fungal and have tried some tea batches =
with small amounts of dried brussel sprout leaves and tested for fungal sup=
pression. So I brewed a batch and tested for fungi then added the dried an=
d crushed brussel sprout leaves and tested again. I did notice a lessening=
 of biomass. However, because I added the leaves after I tested for biomas=
s, the loss could have been a result of the extra time in the brewer with a=
 given amount of O2.

So, I can't say definitively that brassicae plants inhibit certain bacteria=
/fungi and VAMs even though there is plenty of anecdotal evidence that all =
brassicae seem to inhibit certain bacteria and fungi similar to an astringe=
nt. Could I possibly be any more confusing?

Ted Peterson
EW/SOE







Received on Mon Nov 01 2004 - 23:17:11 EST

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