Leaf yellowing

[naoki]

This is an experiment we set up in a Plant Biology lab that I TA. We wanted to see the effect of nutrient deficiencies on sunflowers plants after ~6 weeks of hydroponic culture. Each row is a different treatment in which one nutrient was excluded from culture. I'll try to add more explanations in a different post.

Obviously there are huge differences between monocots and dicots, so take these with a grain of salt. Does anyone know of a similar experiment done with orchids? It seemed really easy to set up, the hardest part would be getting 30 genetically identical orchids to sacrifice to science!

This is pretty interesting. The common symptoms of deficiency are usually from a few crop plants (e.g. corns). So it is interesting to see how other plants respond. I'm surprised that N deficiency isn't as bad as K deficiency (which seems to be one of the worst with sunflowers). Doing it in orchids would be a bit more challenging (slower growth, and their higher capacity of nutrient recycling). But there are some studies which used Phalaenopsis.

If you don't mind (and if your professor is ok), can you share the protocol of this lab? I think your PM or email is disabled, so I appreciate it if you can email (or PM) me.

 

[troy]

Thank you for sharing yur lab experiment with us diane even though they aren't orchids, the visual description of deficiences are cool, question, are the growth production / systems the same for all plants?

 

[PaphMadMan]

Just a thought, ... could it be a genetic sensitivity to too much of some nutrient ? Might be worth trying reduced feeding for a while.

Might be the right track. I was thinking this could be a case of excess of one nutrient (or non-nutrient mineral) inducing deficiency symptoms for another. Symptoms may not be quite typical of a true deficiency. Calcium and magnesium can be mutually antagonistic in this way, or excess potassium or even aluminum might suppress calcium or magnesium, calcium might suppress iron, etc. Since this seems to be lowii (not a calcium lover) hybrids I might look first at reducing calcium without changing anything else and see if the next growths are better. It will take a full growth cycle to know.

 

[Brabantia]

This is pretty interesting. The common symptoms of deficiency are usually from a few crop plants (e.g. corns). So it is interesting to see how other plants respond. I'm surprised that N deficiency isn't as bad as K deficiency (which seems to be one of the worst with sunflowers). Doing it in orchids would be a bit more challenging (slower growth, and their higher capacity of nutrient recycling). But there are some studies which used Phalaenopsis.

If you don't mind (and if your professor is ok), can you share the protocol of this lab? I think your PM or email is disabled, so I appreciate it if you can email (or PM) me.

It is an other publication about the effect of K deficient on Guzmania.
Ref: HortScience 43(1): 146-148 2008 Chao-Yi and Der-Ming Yeh.

 

[Happypaphy7]

I vote for nutrient deficiency or virus.

 

[abax]

It looks to me to be an iron deficiency and I've had quite a bit of experience
with this problem with annuals. The streaky appearance of the yellowing
catches my attention. A once a month or so fertilizing with Miracid helped
and/or entirely corrected the problem.

 

[gonewild]

Troy, the plant has seen fertilizing with an NPK(Mg) 8-12-24-(4) at approx. 1/1000 w/v, to something similar to Ricks K-lite with 90% CaN03 (approx 50 ppm N) and 10% of this NPK fert at about 5g/100 l. Mg Sulfate periodically added. I have seen effects after changing to high N at low conc. but not much with this plant.

Your fertilizer is not similar to Ricks K-lite. Your potassium (K) level is at a ratio of three times more than nitrogen. Your fertilizer is K-heavy!

What you are seeing is the decline or "sudden collapse" of a plant that won't tolerate high levels of potassium. The symptoms look like disease but there is no environmental reason for the plant to have a disease and the disease does not quickly kill the plant. That's because it is not an infection and it is not a nutrient deficiency, it is most likely a nutrient toxic reaction caused by excess potassium.

When you change to high N you are effectively lowering the potassium ratio, that's why you see effects. Lower the K ratio to zero on this plant and see what happens.

 

[Happypaphy7]

Fusarium wilt and other diseases will turn an entire plant into a mushy mess overnight. Not saying this is it, but just read that your comment saying disease do not kill plants quickly.
Plus, disease organisms are usually everywhere. It's when the plants get weak or balance in growing environment breaks that diseases break out or plants become more susceptible to diseases.

A good question is if this is nutrient deficiency or overdose reaction, why only this plant but not many others around it?
I assume they are all treated the same way?

 

[gonewild]

Fusarium wilt and other diseases will turn an entire plant into a mushy mess overnight. Not saying this is it, but just read that your comment saying disease do not kill plants quickly.

Sorry, I think you misunderstood what I said (or meant to say).
My point was that the diseases usually kill the plant quickly and since this problem is just lingering I suggest that it is not a disease but instead related to a nutrient excess.

Plus, disease organisms are usually everywhere. It's when the plants get weak or balance in growing environment breaks that diseases break out or plants become more susceptible to diseases.

Exactly my point.

A good question is if this is nutrient deficiency or overdose reaction, why only this plant but not many others around it?
I assume they are all treated the same way?

Genetics is likely the answer to why some plants tolerate nutrient excess and some don't. Why can one person tolerate more sun than another...genetics.
Other reasons could be environmental related to the condition of media or type of media.

 

[Happypaphy7]

Oops! sorry.

Genetics maybe.
I like all green complex paph with no white halo on the dorsal.
Every single of those I buy or I see at shops has this dark (nearly black) mark along the veins with some rust-like stuff on the surface.
These marks will get worse and worse with time. very frustrating.
Anyways, back to the main post, so maybe it's genetics or virus?
Who knows? lol