Very nice
I think you meant 8.4mg per L of Mn in Kelpak (from Ray's number)
I Everyone says that they don't need much nutrient, and over fertilization is one of the main causes of Disa death.
The difficult decision is whether the deficiency is caused by interference among elements (over fertilization) or lack of it (under fertilization). I could give mancozeb, but I think I should probably take the safer route of reducing fertilizer further more at first.
NH4:NO3 root.growth leaf.area
0:100 230 (ab) 13.9 (b)
20:80 176 (b) 14.2 (b)
40:60 514 (a) 20.9 (a)
60:40 422 (ab) 22.2 (a)
Can you find clarification that the EC was all due to fertilizer in RO/DI/or rain water?
The EC of the basic irrigation water can potentially account for just about all the salts and still have no NPK whatsoever.
What was total N concentration in the drip feed? And the dilution rate?
I've seen habitat info with high ammonia % but total N still under 5ppm. pH will become critical at higher ammonia concentrations as it becomes exponentially more toxic with higher pH (and temp).
Tyrone, I received 7 more seedlings of D. uniflora today, and I was also planning to use LECA for some. But after seeing the high death rate in the experiment, I didn't use it. They don't explain why LECA is so bad for Disa, but it could be just their setting. But they quoted that Wally Orchard's article also mentioned that LECA isn't great for Disa.
I've found that the LECA I have (I think purchased as Hydroton) has a high CEC capacity and holds up salts pretty easy. Could be a big K sink and ultimately run the root dose of K very high.
I've found that the LECA I have (I think purchased as Hydroton) has a high CEC capacity and holds up salts pretty easy. Could be a big K sink and ultimately run the root dose of K very high.
That's a possibility (they used even higher EC fertilizer for testing the different media). But doesn't Sphagnum moss have even higher CEC?
One of the chapter is published in a peer-reviewed journal (South African Journal of Plant and Soil 2007 24(3): 166-171), which is about the nutrients.
??? Not all LECA and sphag created equal.
For not having read the article, are they looking at leaf and root tissue concentrations (like in the Rodriquez paper)?
After couple advises here, I looked around additional scientific studies of Disa culture (hybrid with D. uniflora as the parent), and I found a pretty nice thesis here (scroll down to see the link to PDF):
https://scholar.sun.ac.za/handle/10019.1/3042?show=full
I thought that it might be helpful to some of you.
One of the chapter is published in a peer-reviewed journal (South African Jounral of Plant and Soil 2007 24(3): 166-171), which is about the nutrients.
The experiment showed large effects of NH4:NO3 ratio (which we have discussed in ST many times).
Code:NH4:NO3 root.growth leaf.area 0:100 230 (ab) 13.9 (b) 20:80 176 (b) 14.2 (b) 40:60 514 (a) 20.9 (a) 60:40 422 (ab) 22.2 (a)
root growth is measured in % growth over 266 days.
leaf.area is cm^2
The letters in parentheses indicate the statistical differences. For example if you look at the leaf area, 0% and 20% NH4 treatments had significantly lower leaf area than 40% and 60% treatment.
I wonder if high preference of NH4 may be related to the habitat, some phrags may prefer NH4 over NO3, too? But I guess since temperature dependence of ammonium toxicity (high temp -> more problems with NH4) is found in some plants, high preference of NH4 by cool growing Disa might be an exception.
Condition: 18C day, 13C night, gravel based media, ebb-and-flood hydroponic once a day in winter and twice a day in summer, EC of 0.24mS/cm for the first 2 months and 0.41mS/cm for the rest, pH 5-6.5, 56-69% shade.
So I guess MSU and K-Lite with 100% NO3 may not be so great for Disa.
There are a couple interesting things in the other chapters which I haven't read yet.
- Ammonium nitrate was better than Urea for foliar feeding.
- Drip irrigation was better than Ebb-and-flood.
- Cooled root reduced root growth
- Hydroton (LECA) wasn't suitable for Disa.
Water.
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