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[compost_tea] Vitamin B1



from http://www.uni-hohenheim.de/institute/pflanzenernaehrung/habs684.htm

Effects of thiamine (vitamin B1) application on bulk soil and
rhizosphere microorganisms and on its release from bean (Phaseolus
vulgaris) seedlings. Z. Pflanzenern&aumlhr. Bodenk. 158: 549 - 556.

Azaizeh H. A. , Neumann G. , Marschner H. (1995).

In in vitro studies thiamine mononitrate (vitamin B1) supplementation
(50-1000 mg I-1) significantly increased growth of total bacteria and
fungi isolated from different soils when cultivated in selective
growth media at pH 5.0. At pH 7.0, however, only some of no
significant effects were observed in total bacteria isolated from the
same soils. Growth of Actinomycetes was slightly increased by thiamine
at pH 5.0, but inhibited at pH 7.0 at high concentrations. In most
soils tested, total numbers of bacteria, Actinomycetes and fungi
(determined as cfu g(-1) soil) were significantly higher in the
rhizosphere of 10 d old bean (Phaseolus vulgaris L.) seedlings after
seed treatment with thiamine mononitrate. No significant increases
were observed in total Pseudomonas fluorescens isolated from the
rhizosphere of vitamin-treated plants. In seed and root exudates of
bean seedlings about 12 % of the original seed content of thiamine
(0.9 mu g seed(-1)) were released after 5 days of germination.
Thiamine applied to bean seeds (3 mM in the imbibition solution) was
taken up rapidly and in high amounts. Subsequently, 83 % of this
amount was released from the thiamine- treated seedlings during the 12
days of growth. Within the first 5 days of germination, the treated
seeds released about thousand times more thiamine into the rhizosphere
compared to untreated seeds. The results suggest that a large
proportion of the thiamine applied as seed dressing was released from
the developing bean seedlings and has contributed to the thiamine
supply of rhizosphere microorganisms 


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