Very nice
Disa aurata
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The document I was looking at, http://www.omex.com/agriculture/ProductItem.aspx?id=338, gave the value in g. I guess it was a typo... Oops.
If you are feeding MSU, and MSU has more Mn then the issue could be interference due to another nutrient. So, what are the Ca, Fe and Cu levels in MSU? Maybe you should flush the plant and get rid of as much residual nutrients as possible. What is the potting medium?
Rick
Well-Known Member
I think you be hard pressed to find even 1 or 2 ppm of total N in waters that D aurata grows.
If they really need that much N it would be direct transfer from nitrogen fixing bacteria on the roots since the limited data on water quality in South Africa generally agrees with the rest of the world that if more than a ppm or 2 of N is showing up in surface waters then it's pollution from anthropogenic sources.
I think its really hard to kill a plant from mineral nutrient starvation. Since the whole low K thing, I've been cutting back more and more in the GH and the tropical plants growing on my windowsill are getting nothing but my well water (Which is "non-detect" for NPK). I've got a rescue hybrid Phal on the kitchen counter that hasn't been fed for a year, and grew a new set of nice dark leaves just fine.
I think cutting back is the way to go too.
naoki
Well-Known Member
Thank you, all. It is in mostly perlite (the normal/small size) with a bit of chopped sphag. I have soaked them in pure water overnight a couple days ago. I should have measured the pour-through, but I forgot.
After rereading tenman's article, he rarely fertilizes them. Actually, there are some yellowish leaved plants in tenman's homepage. Do you know the cause, or is it not an issue?
After rereading tenman's article, he rarely fertilizes them. Actually, there are some yellowish leaved plants in tenman's homepage. Do you know the cause, or is it not an issue?
naoki
Well-Known Member
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).
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.
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.
Last edited:
Rick
Well-Known Member
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).
I would agree in general that tiny frequent applications are better than big infrequent applications. Plants are trying to grow 24/7 and not just on feeding day. Most of what we dump on the plant on feeding day is wasted, and unavailable the rest of the time.
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).
I would agree in general that tiny frequent applications are better than big infrequent applications. Plants are trying to grow 24/7 and not just on feeding day. Most of what we dump on the plant on feeding day is wasted, and unavailable the rest of the time.
Darn. LECA was my plan for next year. I will have to download the thesis and give it a careful look.
I don't think there is any problem with the you N-source. Your plants are growing well. The issue with uniflora hybrids is that they can flower so well that they don't bother setting a new tuberoid. You have to cut the stem or remind the plant that winter is coming by keeping it really cool.
I don't think there is any problem with the you N-source. Your plants are growing well. The issue with uniflora hybrids is that they can flower so well that they don't bother setting a new tuberoid. You have to cut the stem or remind the plant that winter is coming by keeping it really cool.
About the LECA:
From the thesis: "Hydroton with a layer of palm peat on top and hydroton with a layer of acid peat on top. The pH of the acid peat was altered by the addition of agricultural lime (5.6 g/L). "
I'm not sure how anything grows in that... Still, bad news for my Disa experiment for next year. Then again, they weren't using K-lite.
From the thesis: "Hydroton with a layer of palm peat on top and hydroton with a layer of acid peat on top. The pH of the acid peat was altered by the addition of agricultural lime (5.6 g/L). "
I'm not sure how anything grows in that... Still, bad news for my Disa experiment for next year. Then again, they weren't using K-lite.
naoki
Well-Known Member
Rick, they mixed the fertilizer from basic salts, so it is most likely that the EC is from fertilizer (i.e., they don't mention specifically, but I can't imagine that they would use tap water or well water for scientific experiments about nutrition). I found out the published paper is also freely accessible, so I added the link above. It's in their Table 1.
I haven't read the drip feeding chapter yet. I think you can calculate the N concentration for the ebb-and-flood (from Table 1 of the published paper), but it seems a bit tedious, so I haven't done it. Also, there seems to be an error/typo about EC: the table says 0.73mS/cm, and the text says 0.24-0.41mS/cm.
The thesis did mention that they have tried even higher fertilization (about twice). Contrary to what we expect for Disa, they could handle it for the short-term. However, as expected, shoot:root ratio become high; i.e., more above ground biomass as we expect from higher fertilization (this pattern is common in plants). Higher fertilization also resulted in lower probability to develop tuber, so the plants end up dying after flowering. I've heard this kind of death after flowering is pretty common in D. uniflora, so reduced fertilization is required. Well, low fertilization is what everyone says, but it is good to see the numbers in a controlled experiment.
You are right about pH and temp. They were looking for the interaction between temp and NH4 toxicity, but they didn't see it. I think in the potting media chapter, I think the low pH of the media was important. I'll probably start to adjust the pH with vinegar (like for Cyp. acaule).
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.
Rick
Well-Known Member
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.
naoki
Well-Known Member
That's a possibility (they used even higher EC fertilizer for testing the different media). But doesn't Sphagnum moss have even higher CEC?
NYEric
Well-Known Member
Chem nerds! 
I think the idea with the peat was to push the positive salts (e.g. K) off the medium (i.e. LECA) with hydrogen ions... But all they managed was to smother the roots as, no doubt, the peat got between the clay and created a nasty bog.
The solution may be to water with a mildly acidic fertilizer? Perhaps some tea in the RO water to routinely rinse the LECA? I have noticed salt buildup on the top layer of LECA around my Paphs. I just blast this off with the spray bottle or switch out for clean LECA. Salt accumulation could become a problem without regular flushing.
Rick
Well-Known Member
??? 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)?
Rick
Well-Known Member
Trying to put this link back in with a possible correction on spelling since I was only getting errors when I tried to pull it up.
Still can't get it.
You can download the entire thesis for free off the University of Stellenbosch website Naoki linked to: https://scholar.sun.ac.za/bitstream/handle/10019.1/3042/pienaar_study_2005.pdf?sequence=1
naoki
Well-Known Member
No, they are interested in the growth over a year, so no tissue analyses.
Sorry for the wrong link, how about this?
http://www.tandfonline.com/doi/pdf/10.1080/02571862.2007.10634801
With LECA, they get about 50% mortality (while the mortality was close to 0 for the other types of media). This part isn't in the published paper (it is in the thesis). You are right, there appear to be a variation within sphag. I think they mentioned Chilean vs NZ.
gdupont
Well-Known Member
Sorry to be dragging this post up from quite awhile ago... So, what kind of fertilizer is best for Disas, then? Could you distill this knowledge a bit more? Thanks!
NYEric
Well-Known Member
Water.
I was told "distilled water" but I suppose rain water is OK too.
oke: The less fertilizer the better.Anecdotally, regular sprayings with Seagrow work well. I tried this and it didn't kill the plants but the live sphagnum they were growing in wasn't happy about the Seagrow.
