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

From: Thomas Giannou <thomas_at_tandjenterprises.com>
Date: Tue, 2 Nov 2004 10:30:54 -0800

Hi Elaine,

Taking one topic at a time. In an earlier post I showed an abstract that s=
tated that mycorrhizal plants and brassica can indeed be planted together. =
 That particular abstract stated, "No inhibition of AM colonization was obs=
erved in host plants that were grown in the same pot and at the same time a=
s non-host plants. However, when non-host plants were grown for 30 d before=
 P. sativum, they inhibited mycorrhizal colonization of the latter."

Below is the abstract I was referring to in my message. This is an example=
 where mycorrhizal host plants can be planted with non-mycorrhizal plants a=
t the same time and the AM fungi was not inhibited. I am not trying to gen=
eralize anything. I was talking about this particular research finding. B=
ased upon this particular finding, it is not unreasonable to think that a s=
imilar coplanting situation MAY exist with other Brassica plants especially=
 in consideration that other Brassica plants were actually colonized by AM =
fungi as I noted in at least one other abstract that I posted in a prior me=
ssage. (I reposted that abstract below.)

                                       ------------------------------------=
--------------------------------------------------------------------
Fontenla, S; Garcia-Romera, I; Ocampo, JA. 1999. Negative influence of non-=
host plants on the colonization of Pisum sativum by the arbuscular mycorrhi=
zal fungus Glomus mosseae. Soil Biol. Biochem., 31: 1591-1597.
Address:

JA Ocampo; CSIC, Dept Microbiol, Estac Expt Zaidin, Prof Albareda 1, E-1800=
8 Granada, ; Spain; CSIC; Prof Albareda 1; Granada; Spain; E-18008.


We studied the influence of the arbuscular mycorrhizal (AM) non-host plants=
 Stellalria media (Caryophyllaceae), Chenopodium album and Spinaceae olerac=
ea (Chenopodiaceae), Brassica campestris, B. nigra, Capsella bursa-patoris =
and Sisymbrium altissimum (Brassicaceae), Juncus balticus (Juncaceae), Urti=
ca campestris (Urticaceae) and of the AM host plant Taraxacum officinale (A=
steraceae) on the colonization of Pisum sativum by the AM fungus Glomus mos=
seae. None of the non-host plants tested were colonized by Glomus mosseae. =
Older non-host plants competed with P. sativum. No inhibition of AM coloniz=
ation was observed in host plants that were grown in the same pot and at th=
e same time as non-host plants. However, when non-host plants were grown fo=
r 30 d before P. sativum, they inhibited mycorrhizal colonization of the la=
tter. In a split pot system the presence of U. dioica on the left-side decr=
eased AM colonization of P. sativum roots on the left-side, but not on the =
right-side. Non-host plants decreased the inoculum potential of G. mosseae =
and in some cases the percentage AM colonization of host plants cultivated =
after non-host plants. These results indicate that roots of non-host specie=
s have factors that seem to affect the AM fungus before it establishes in t=
he root of host plants. (C) 1999 Elsevier Science Ltd. All rights reserved.=
 
                                            -------------------------------=
--------------------------------------------------------------

In the abstract below, Cabbage seedlings (Brassica oleracea, var. capitata,=
 cv. Hercules) were inoculated with AM fungi and were colonized and were be=
nefited. Hercules cabbage is a fairly nice vegetable plant that would fit =
in most gardens. Since this particular cabbage was colonized by AM fungi, =
and no mention of inhibition is found in the abstract, it is not unreasonab=
le to think that another mycorrhizal plant could be planted right along sid=
e these Hercules cabbages and quite likely would not have a problem. Also=
, to now say that all brassica are non-mycorrhizal is incorrect.

                                          ---------------------------------=
---------------------------------------------------------------
Nelson R; Achar PN. 2001. Stimulation of growth and nutrient uptake by VAM =
fungi in Brassica oleracea var. capitata. BIOLOGIA PLANTARUM. 44(2):277-281=
.

Address:

Univ Durban Westville, Dept Microbiol, ZA-4000 Durban, South Africa.


Cabbage (Brassica oleracea, var. capitata, cv. Hercules) seedlings were ino=
culated with vesicular-arbuscular mycorrhizal (VAM) fungi Glomus fasciculat=
um, G. aggregatum,, and C;. mosseae. Differential efficiency in mycorrhizal=
 colonization and the specificity of fungal symbiont to stimulate the growt=
h and nutrient uptake of the host were observed. In addition, there was an =
increase in phenol, protein, reducing sugar contents, and peroxidase activi=
ty in the VAM inoculated seedlings. Since these compounds are known to conf=
er resistance against fungal pathogens, the use of VAM as a biological cont=
rol agent to protect cabbage against several root diseases is suggested.
                                                         ------------------=
----------------------------------------------------------------

Best Regards,
Thomas Giannou
http://www.tandjenterprises.com



  ----- Original Message -----
  From: soilfoodweb_at_aol.com
  To: compost_tea_at_yahoogroups.com
  Sent: Tuesday, November 02, 2004 7:28 AM
  Subject: Re: [compost_tea] Exudates (was: Re: Brassicas and vam fungi)


  Thomas -

  It sounds like you have concluded that brassica, in general, and VAM-requ=
iring plants can be grown together. That is not the conclusion that would =
be taken from the papers you pointed out. You have not demonstrated that a=
nyone is suggesting that brassica and mycorrhizal plants can be GROWN TOGET=
HER.







Received on Tue Nov 02 2004 - 16:54:36 EST

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