plant deficiency experiment

Nancy Longnecker longneck at UNIWA.UWA.EDU.AU
Fri Feb 23 03:35:32 EST 1996


>I've got a question about a nutrient deficiency experiment I'm trying to
>run in intro botany lab.  I'm following the experiment in Vodopodich and
>Moore's "Botany" lab manual on p160-161.  I had the experiment set up on
>Monday, with tomato seedlings (about a month old) growing in perlite and
>being watered with Hoagland's solution minus one of the essential
>nutrients.  The problem is, the plants in all treatments but the "water
>only" control are dying.  Now, I've got a couple of flats of backup tomato
>seedlings that I can use, but I need to figure out why the plants are
>dying.  The only chemical I substituted from the Hoagland's solution recipe
>listed in Vodopodich  and Moore is Molybdenum trioxide instead of
>H2Mo4*4H2O .  Could that have caused the problem?  Any suggestions??
>

Hello Timothy,

I doubt the Mo is your problem.  If the old leaves on your plants had
brown, burnt looking edges, a good guess is that they are getting "too much
of a good thing" and are suffering toxicities.  (Hoagland's solution is
actually pretty concentrated stuff.  We tend to use much more dilute
solutions for our research work.)

If you are adding Hoagland's frequently and the plants are transpiring alot
because of high temperatures and sunny days, salt accumulation can be a
problem.  One solution is to rinse  occasionally (~1/ week) with water;
then immediately add your nutrient solution.  That way, you leach out any
salts which might accumulate but the plants don't have any period of
deficiency.  You can also top up with water between additions of nutrient
solution.  If you want to show some of the micronutrient deficiencies, you
obviously have to use a clean source of water.

Good luck!

Nancy


________________________________
Dr. Nancy Longnecker
Education Coordinator
CLIMA (Centre for Legumes in Mediterranean Agriculture)
The University of Western Australia
Nedlands, Western Australia   6907

email: longneck at uniwa.uwa.edu.au
http://www.uwa.edu.au/cyllene/climaweb
ph: 61 (9) 380 2492
FAX: 61 (9) 380 1140
________________________________





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