Experiment with Rhizobia and Nitrogen Fixation: help.

mccardaj at esvx24.es.dupont.com mccardaj at esvx24.es.dupont.com
Wed Nov 2 16:12:36 EST 1994


In article <CyMGnq.89w at freenet.carleton.ca>, an524 at FreeNet.Carleton.CA (Jeffrey Ehlinger) writes:
>
>        I am doing a project at school having to do with
>the effect of Rhizobia on nitrogen fixation in bean plant.
>I plan on having four treatments (Low N/Rhizo, Low N/No Rhizo,
>High N/Rhizo, and High N/no Rhizo). I will measure plant
>bio-mass after five weeks of growth or before plants flower
>(whichever comes first).


Hi Jeff,
I tried to Email this to you directly but the address from your memo header
did not work for me.  

The captan on the seads probably won't harm the Rhizobia.  However, many times beans have some 
beans have some viable Rhizobia on their seed coats and you will want to wash
the seeds to remove them.  I have worked with soybean (and B. japonicum) and
we always rinsed the seeds with tap water and then swirled them in 70% ethanol,
for aor 2 to 4 minutes to surface disinfect the seeds.  You will need to check that
the beans you are working with can withstand the ethanol treatment.

The major difficulty of the type of experiment that you are planning is 
cross-contamination of uninoculated plants with Rhizobia from the inoculated
plants.  Air-borne contamination is not an issue.  The problem occurs
primarily when water splashes from one pot to another when watering the plants.
If possible, you will want to segregate the uninoculated plants.  You will also
want to avoid cross-contamination caused by drainage from the bottom of the po
pots.  The key is to water very carefully and to have all pots in saucers.
Watering equipment such as hozes and spray wands should be kept clear of the
pots or you could end up with contamination from these sources.  

We never found it necessary to cover the tops of the pots with plastic.
As long as you can space the plants and carefully water them, you won't have
any problems.  

How were you planning to inoculate?
Good Luck.
A.J. McCardell
mccardaj at esvax.dnet.dupont.com
(302) 695-3041



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