Dynamic accumulation and passive ionic uptake crossroads?

[Douglas.Curtis]

You want to accumulate some things though. I load P through veg. Some feed regimes also do this.
John likes to load Ca. I have followed this but I'm aware it's somewhat immobile.

Our experience working with non live soils has no bearing on the discussion, other than as a reference to a broken system.

The question is in regard to plant physiology itself and the concepts surrounding how the systems should run.

 

[ICGA]

Great example, and one (among many I am sure) I was not aware of. So substitution exists, wanting one element and absorbing another instead. Does this translate to fixation of excesses, making it accumulate the Na when it is present in too high a concentration?

I think you will see different results with hydro and salts type situations vs. Organics where the plant evolved to trade carbs to the microriza more below:

Cadmium is simply one element known to be accumulated by cannabis. An example, if you will.

The question is more about why the passive ionic uptake path is bringing in unusable elements. Granted, the answer will likely be rather different for standard grows than for fully functional live soils. I'm interested in the answer for both methods of course.

Anyone have comprehensive links on the fixation process for excess elements, A.K.A. dynamic accumulation? I'm looking for additional info on how the plant does this. Perhaps there will be clues in the dialog.

I think there will be a difference if you tested the same clone in the same environment the only difference being living soil and organics vs salt based fertilizers in low CEC mediums because the plant evolved to trade more than half of the carbs generated threw photosynthesis to the mycorrhizal fungi in exchange for the mycorrhizal fungi trading carbs to different kinds of bacteria who solubilise and chelate more specific elements threw their natural metabolic activities in the soil. This allowes the plant to controll the soil economy because it can manipulate the micro heard by stimulating the growth of specific micro organisms in order to controll if something becomes more or less soluble and more or less bioavailable. This is also done by promoting bacteria that raise or lower the soil PH as the plant sees fit, which effects what element are more or less soluble. There is also probably other forms of signaling going on as the mycorrhizal fungi is literally growing into the cell wall of the plants. Where as; soluble salt fertilizers in low CEC environments don't allow the plant to control which nutes are in solution at a given time threw Cation Exchange and via soil biochemical calibration of the symbiotic relationship with the micro heard.

 

[Douglas.Curtis]

Ty so much for that, I want to reply immediately but will have to do so this evening when I have time.

 

[Douglas.Curtis]

Long day... scheweeeew!

So you are quite correct on many points, and indeed the plant can signal for what it wants through the root exudates.

As has also been discussed, plants are known to uptake Na when desiring potassium.

We also have the example of plants absorbing iron oxide (not a usable form by the plant) when they need iron redox and are unable to get it.

So, back to the original question. What elements are the plants looking for, and do not have access to, which causes them to absorb large amounts of heavy metals like cadmium?

Clear'er?

 

[Ca++]

Cadmium is freer in low cec substrates. Like most things, its bonds with other things change with pH. At a typical pH it bonds with chlorine and that chloride isn't very attractive. However below pH5 it may exist as a ++ like Ca and Mg. My weak understanding is that hydrogen is chucked out by plants in an ion exchange to get such things. So a plant will chuck out H++ to get Ca++ or Mg++ and get Cd++
Other metals may also exist as ++ such as Fe.


There are other Cd compounds that can be taken, if they are ++
We are talking about ion exchange. Balancing electron numbers to keep an equilibrium. The plants taking in water, and hydrogen is created through process, that has various states. As H with two electrons is secreted, something else with two is absorbed. This means the plant isn't being selective. It gets what is available, and must store what it can't use. We must ensure the ratio's present are as good as can be.


It doesn't matter if it's soil or hydro.



I'm way out on a limb with this post. I didn't do chemistry at school. The chloride ph and ++ bit is from a search though. As I have never needed to look at Cd before.
Like our plants, I tend to accumulate more than needed.

 

[Cerathule]

Doug, I'm attaching a book where some chapters detail specifically how Cd and other micronutes are mobilized and transported into the plant.

 

[Douglas.Curtis]

Rock on! That's a bit of traction, thanks so much to both of you. I'll digest this and the pdf and be back.

 

[Ca++]

Cerathule has the right idea....



...directing you to the national library



I deionised a crop once. I watched with mystification as a leaf rose up towards my face, reach out it's middle finger towards my nose, sending me bozeyed. When twang, it bridged the gap with a spark and fell away again. Or I pulled back. It was a bit of a haze.
WTF moments don't get much better than that

 

[Douglas.Curtis]

That's awesome I remember shuffling around the carpet in socks, carrying a piece of tinsel from the xmas tree. It would do the same thing to the stereo... lift up and spark the gap before falling back. lol

Ok, so I was reading and making notes for a post when I had to stop and post what I have so far. lol I kinda kept typing, so it will read a bit funny. lol
----------------------------------------------

Great stuff, for me anyway, I love learning. Though I'm not aware which sections actually have relevance to cannabis, the biological interactions are fascinating.

When there is an iron deficieny situation, Strategy II plants release nonprotein amino acids (hytosiderophores and phytometallophores). These amino acids are capable of chelating much more than just iron. They're capable of chelating most of the transition metals.

Ok, that's a big deal because transition metals are elements which have valence electrons. Using valence elctrons they can form chemical bonds in two shells, making them very handy for alloy compounds. Among many others, the main transition element micronutrients we want for plants include magnesium, molybdenum, cobolt, iron, nickel, copper and zinc. The transition element group also includes the heavy metals we do not want (at least not in any significant amounts), cadmium, lead and others.

In the case of iron, (and keep in mind this is only happening during iron deficiency)... oh wait... is that it?

What other processes produce these amino acids? Without these amino acids being available the transition elements are not readily available, they need to be chelated first for easy absorption.

Well that's one point to ponder. At least some heavy metal chelation and absorption can be prevented (if cannabis is a Strategy II plant) by providing adequate levels of iron within the plant.

Ok, gonna go read more... again, ty so much.

 

[Three Berries]

I was just reading up on excess iron exposure and the changes a plant goes through if too much. It can stunt the plant quite a bit..

I've been sprouting my seeds over the last few years with the paper towel on a now rusty coffee can. Once sprouted and in soil sometimes the seeds were really slow to do anything some never came up.

I was suspecting iron poisoning.

 

[Douglas.Curtis]

Given the current reading, I would say that's a fair guess as to the reason. Lately I've been reading maaany reasons why it's beneficial to sprout directly in the only container/soil the plant will live in, at least as far as full health and pest resistance is concerned. Still, I'd like to see your results change by simply using a new coffee can instead for a few.

Notes made from further reading of the pdf...

Metals use channel proteins and/or carrier proteins to enter cells.

Several pathways and mechanisms operate for the transportation of heavy metals. They form either a channel or a pore through which metal ions are transported into the plant.

Trans-membrane helices are pore like structures which mediate the transport of metal ions. They are either cysteine-rich or histidine-rich.

The transporters involved in metal ion uptake:

NRAMPs Natural Resistance-Associated Macrophage Proteins)
Mn2+, Zn2+, Cu2+, Fe2+, Cd2+, Ni2+, and Co2+
AtNRAMP3 is specifically involved in Cd uptake and sensitivity, expressed in vascular bundles of roots, stems and leaves;it has function in long-distance metal transport (Helps it get from roots to shoots)


CTR(animals and fungi)/COPT(plants) Copper Transporters
Specifically channel CU2+ ions.

ZIP ZTR/IRT related proteins
Transport divalent cations across membranes.
Fe, Mn, Zn and Cd
ZIP proteins have eight trans-membrane domains
ZRT1 gene is activated under Zn deficient conditions

P1B-type ATPases form a phosphorylated intermediate and are called HMAs (heavy metal-transporting ATPases)

 

[Three Berries]

Given the current reading, I would say that's a fair guess as to the reason. Lately I've been reading maaany reasons why it's beneficial to sprout directly in the only container/soil the plant will live in, at least as far as full health and pest resistance is concerned. Still, I'd like to see your results change by simply using a new coffee can instead for a few.

This time I did keep them segregated from the rusty can. Also sprouted them vertically. So far so good.

 

[Douglas.Curtis]

Ok, so there's a whole lot more in the pdf but it deals mainly with how the plants handle what they've taken up. Heavy metals are rather toxic and plants have some ways of dealing with it, to a point.

Chlorophyll function can be hindered when Zn, Cu, Cd, Hg or other elements are replacing its Mg2+. Not sure if this is relevant, but might be if the condition triggers any other processes. Stay tuned...
Nah... looks like this is only dealing with post absorption issues and does not affect the continued absorption of them. moving on...

Toxic heavy metals can replace Zn and Mg2+... much to the dismay of the plant it's in.

When heavy metals are substituted for the correct element in a protein, is there a possibility it can alter the function enough to provide transport for a different element? As in, some heavy metal toxicity can create proteins which create and/or increase the absorption of different metals/elements? That's a stretch, no? lol

Hyperaccumulator plants transport heavy metals into vacuoles for storage.

That's about it for relevance, I believe...
(yeah... I had chores I had to do during this but I do read rather quickly. lol)

 

[Cerathule]

When heavy metals are substituted for the correct element in a protein, is there a possibility it can alter the function enough to provide transport for a different element? As in, some heavy metal toxicity can create proteins which create and/or increase the absorption of different metals/elements? That's a stretch, no? lol

Most of what should happen is a loss of function of said molecule. That's what's happening when O gets fixed over C in C3 photosynthesis, or when Na rivals K.

Without Mg but other metals at the center of the porphyrin ring it may alter the absorption spec of that chlorophyll...

I'd expect most - if not all - such exchanges weigh tendencially negative into the whole system. If there would be a benefit, a positive function, like with Si, fulvics, etc, then these would've been recognized as such already by scientists and labelled as 'beneficials'.

Mineral mobilisation & absorption is really a complex and wide field. The plant's roots secrete hundrets of different compounds. The usual interpretation is "it feeds the microbes", but in reality it does much much more. The acids released also dissolve minerals or "stones", bring these into aqueous solution to be able to uptake it.
The roots release a large number of protium (H+ ions) to acidify the rhizosphere, ionize/reduct elements to be able to better attract them via an electrochemical gradient build up by large organic molecules behind the plasmalemma. The landplants diet consists of more kations than anions so there's that. This mismatch will be counterbalanced by decomposing plant matter in nature, but not in an artificial pot culture.
Once at the root they get exchanged by ion transfer (lots of Ca is used here, too) and there are different transporters available, ion channels, ion ports (also antiports, symport ie. they either bring something else out or something else in alongside with it) and and and.
There's whole books filled with these informations but the topic is far from being understood, so alot of research happens. The way how some element can travel through the root cells (symplastically) or alongside these (apoplastically - the fluidic space between the cells) has also heavy influence later up in the plant in the way these nute ions can be (re)translocated from place to place, because the cellwalls may have some of the same "receptors" or "doors" that is one step in the mechanism to allow such a travel.

One can go into great depth with that which I did/tried, but then terminated at some point because of the lack of practical consequences.
What I did learn was the obvious
- keep toxic substances out of the substrate as best as possible
- plant needs steady supply of elements that show a mostly passive uptake kinetic (Ca, B, Mg to some extent)
- longterm fertilizer deposits in the substrate enable the plant some control over the ion intake. but these dimensions are dwarfed by when you grossly overfeed. outside in nature soil is usually deplete of nutrition and plants grab whatever whenever they can, the humus constantly decomposes and releases a bit to the free soilwater

 

[Douglas.Curtis]

That's about the size of it. Thank you so much for the contributions.

 

[YellowCanaryConsulting]

Glutathione, excuse me, "phytochelatinoid" production is a recreational activity to the Cannabis plant. That's why it loves fungus, they can share Glut and B vitties and make some nice thiol antioxidants. Cannabis attached to fungal networks hunts free radicals and attacks peroxides for fun.

Before thiosulfates this was standard in high end hydro recipes:

"Ten micromolar CdCl(2) in the nutrient solution induced a 100% increase in sulfate uptake by roots. This was not observed either for potassium or phosphate uptake, suggesting a specific effect of Cd(2+) on sulfate transport."


We in the future now. Thiosulfate is a preferred sulfur source. Much less NADPH/ATP usage. Less Glut-bound cadmium stored in the vacuole.



PS the notion that plants selectively exude anything in the presence of microbes is unfounded. If the microbes are present, they've already chelated the nutrient with their fatty acid, the plant has no reason to re-enact the job of the microbe.. It simply takes in the fatty acid and whatever is attached. The plant will not choose what it wants unless you are growing on gravel, sand, and stone, with zero microbes.

 

[dramamine]

Glutathione, excuse me, "phytochelatinoid" production is a recreational activity to the Cannabis plant. That's why it loves fungus, they can share Glut and B vitties and make some nice thiol antioxidants. Cannabis attached to fungal networks hunts free radicals and attacks peroxides for fun.

Before thiosulfates this was standard in high end hydro recipes:

"Ten micromolar CdCl(2) in the nutrient solution induced a 100% increase in sulfate uptake by roots. This was not observed either for potassium or phosphate uptake, suggesting a specific effect of Cd(2+) on sulfate transport."


We in the future now. Thiosulfate is a preferred sulfur source. Much less NADPH/ATP usage. Less Glut-bound cadmium stored in the vacuole.



PS the notion that plants selectively exude anything in the presence of microbes is unfounded. If the microbes are present, they've already chelated the nutrient with their fatty acid, the plant has no reason to re-enact the job of the microbe.. It simply takes in the fatty acid and whatever is attached. The plant will not choose what it wants unless you are growing on gravel, sand, and stone, with zero microbes.

How do the PSB bacteria play into this dynamic, as you see it? Been wondering about that. These bacteria feed on thiosulfates, don't they? Thanks for the interesting post.

 

[Cerathule]

The plant will not choose what it wants unless you are growing on gravel, sand, and stone, with zero microbes.

https://www.botanicare.com/hydro-101/selectivity-of-plant-nutrient-ion-uptake/

"The movement of ions into plant roots occurs by both active and passive transport. Passive transport means that the ions are carried with the uptake of water into the plant without energy from the plant. The water movement factors that affect passive transport are temperature, humidity, photosynthesis rates, concentration of ions in solution versus within the plant cell, and plant transpiration rates based on stage of growth. Active transport requires energy from the plant and ion movement is determined by competition between ions based on their individual charge. The monovalent ions (single charged) are moved into the plant more easily than divalent ions (double charged), while divalent ions are taken up more easily than trivalent ions (triple charged). This means that the plant will accumulate more potassium (a monovalent ion) than calcium and magnesium (divalent ions) due to the difference in their charge.

Plants typically maintain a negative interior (inside the plasma membrane) relative to the exterior. The slightly negative state of the cell interior and the environment must be maintained and, thus, is related to ion uptake. When there are more cations than anions present, the overall charge becomes excessively positive, and an increase in anions or a decrease in cation uptake occurs to restore physiological conditions. For example, an excess of ammonium (NH4+) cations decreases the uptake of potassium (K+), calcium (Ca2+), and Magnesium (Mg2+). The same relationship exists for anions – excess anions lead to a lower uptake of anions or an increase in cations to balance the cell’s charge. If nitrate (NO3-) is the major anion in excess, then the uptake of cations such as potassium (K+), calcium (Ca2+), and Magnesium (Mg2+) will increase to compensate for the overall negative charge caused by excess nitrate levels."

Some of these ports are active, meaning the plant can choose to use them, or keep them closed - as a means to regulate its internal chemistry.

Of course when you feed EC 15 with 10 fancy super duper tiger bloom bottles to periodically sledgehammerflush the tox out this won't help much.

Still, the physiology of plant cells is there and independantly of microbes. If anything, the plant controls the microbes by feeding them or regulating substrate pH: