I'm Falafel, and this is my perpetual grow log. I'm shitty at keeping track of the little things as they add up so, I'm gunna use this as my reference from now on. Any input is welcome, I love learning and spreading knowledge. Right now I have a 3x3x6 tent for mothers and clones and a 4x4x7 tent for veg/flower with a 4x4 table. I'm new to perpetual growing so in time, I'll have the kinks worked out.
Currently I have a GSC mother growing in soil from seed. I found her in a sac I got a few years ago so we'll see how it goes. I have 10 clones of her in the 4x4 right now that are going into 12/12 next week. They've been in veg 3 weeks now, but they're still little because they got fried as babies lol. I'm using tap water, microflora, and florabloom with readygro coco in 1 gallon containers that drain to waste all under a 1k hps. I pH to 5.8 with ppm at 650 (0.5 conversion). I'll post some pictures of the setup later today. So far my drip system has been adequate but it's a mess. I'm building a setup out of pvc today that will let me switch from 12-24 sites and distribute water more evenly.
Also I have a mendo breath clone and sfv og kush that are aspiring mother plants. So yeah those will be awesome to grow out, but that's all for now. Peace farmers!
Here's this weekends project and some baby pictures. I'll post some pics of the mother later. I'm gunna set everything all set up tomorrow and throw in a couple more clones. I didn't think I was going to use them so they got a little neglected lol
Got the drip system all finished up today and threw in 2 more clones. I had to kill off the mother plant though, she was just taking up too much space. I got a replacement in veg just in case she’s super fire. If not I got sfv og kush and mendo breath to play with. Only time will tell.
Awesome! I kind of did the same thing but kept the overgrown mother and decided to grow her out in a tiny 3x2 cabinet lol have like a dozen clones too. Rock on!!
Awesome! I kind of did the same thing but kept the overgrown mother and decided to grow her out in a tiny 3x2 cabinet lol have like a dozen clones too. Rock on!!
I started noticing some reddening of the stems starting at the petioles and an over all lack of luster to the leaves. My immediate thought was Mg deficiency but after some reading in the stickies i’ve come to think it was my light source. It totally makes sense too, I was running to intense of a light in the wrong spectrum. I’ll add a link to the thread I was reading but essentially hps lights cause an increased demand for P which according to mulders chart is beneficial to Mg absorption however it competes with Ca in the root zone. This left an abundance of Ca to be transpired through the leaves because there wasn’t enough P to compete with it. My guess is that this increased Ca started blocking Mg absorption and causing these problems. For now I’m running my 600 watt MH to let the foliage recover.
I have two beds going right now one MH and one HPS and they both have GSC. The GSC buds under the HPS are stacking nicely and the ones under the MH are going cookie crumbs. I had a feeling that GSC needs more P and I think I am right after this recent observation.
I'm a bit late to this original question; but got compelled to do some sniffing around. I hope this ends up being on point and informative. I do not want to butt in or state things that are commonly known. Hopefully as well this doesn't get too long. I've been down several "rabbit holes" recently and like this; they can seem to keep expanding as you go down, but some are connecting now.
This is presented as data and possible rationalizations or theorizations for things related to light and nutrient use.
Okay, so this cannot be covered without bringing you all in to the rabbit hole some; though many of you I'm sure will know some, much or possibly all. Hopefully I can put this together so things make sense for those that may not know all these aspects (I did not).
First we need to look at "light-dependent reactions" (wiki) and "light-independent reactions" (wiki).
-Of particular note here is Photosystem I and Photosystem II (PSI / PSII) along with Cytochrome for dependent reactions and Calvin cycle for independent.
There is a good You Tube video that explains really well how PSI and PSII were discovered and also explains their interconnection fairly well. (Video)
Finally here with, sort of, the primer section. Another good paper (.doc) that explains PSI and PSII and their differences (Paper)
-From these last 2 links (video / paper) there are a few things to take note of. With the video, the Emerson Enhancement Effect (EEE) and points of "heat" noted. With the paper, the non-linear (cyclic) electron flow and its' involvement with ferrodoxin. (This also is an area where the Cytochrome is useful from wiki links.) As well, that these PSI / PSII reactions occur in the thylakoid membrane. The last thing to note with the paper is PSII Light Harvesting complex (LHC).
that's the end of the "primer" section:
Now looking at ion uptake in regards to spectrum (as per the OP title); I did find one good paper (though they didn't cover all elements). (Paper)
"...the most complete action spectrum for inorganic ion uptake by green plant is that of van Lookeren Campagne (1957). He found that net Cl influx in Vallisneria spiralis was light-stimulated with an action spectrum identical to that of photosynthesis in this organism." Simonis and Mechler (1963) showed that the incorporation of exogenous Pi into TCA-solubule compounds had and action spectrum similar to that of photosynthesis and of total Pi uptake, in Ankistrodesmus braunii."
....."These data would strongly suggest that these active anion influx processes are light-stimulated via the photosynthetic pigments. No data seems to be available in the literature for teh action spectrum of cation transport processes"
The paper goes on to look at CO2 fixation in relation to specific spectrums and intensities. "Fig 1. showes the effect of intensity of light of 448 nm on CO2 fixation in Hydrodictyon africanum. It will be seen that there is a wide range of light intensities at which the rate of photosynthesis is proportional to light intensity, and that there is a fairly abrupt transition to the light-saturated rate."
......
"Similar linear relations between light intensity and rate of photosynthesis have been found in experiment with light of 680 nm and 539 nm. The light-saturated rate of photosynthesis is the same for 680 nm light as for the 448 nm light, anf for flourescent ('white') light. The highest intensity available with the 539 nm light (14,800 erg /cm2 /sec) was insufficient to saturate photosynthesis. "
Figure 1 View attachment 480914
Of note here is that (with CO2 fixation) the saturation was the same for 448, 680 and white light, but that 539 was able to saturate higher. Saturation point shown @ 10,000 erg/cm2/sec . This equals 10 Watts/m2 of that individual spectrum (range).
"Fig. 2 shows the pooled results of a number of experiments in which the effect on photosynthesis of an incident intensity of 500 erg/cm2/sec of light of various wavelenghts was determined...........It will be seen that the resulting action spectrum is typical of absorption by chlorophyll, with a peak in the blue and another in the red at about 675 nm."
Figure 2 View attachment 480916
The paper goes on then, to cover influx saturation intensities and influx over various wavelengths for K, Cl and Na (including some also on efflux).
Regarding K influx; "It will be seen that light saturation occurs at about 2,000 erg/cm2/sec of 448 nm light, and that the influx is linearly related to light intensity below 1,000 erg/cm2/sec. Similar results have been obtained at other wavelengths: light-saturated rates of K influx are identical at 448, 539, 680 and 710 nm, and in fluorescent light.
......"Fig 4 shows the action spectrum for K influx, expressed in the same way as Fig 2 for photosynthesis. The red and blue peaks, and the green trough in the action spectrum are quantitatively similar to those in the photosynthetic action spectrum"
Regarding Cl influx; "Fig 5 shows the intensity dependence of Cl influx supported by 448 nm light. It will be seen that the process saturates at about 1,000 erg/cm2/sec of 448 nm light, and that below this intensity the Cl influx is linearly dependent on light intensity. ...... Light saturated rates of Cl influx are identical at 448, 539 and 680 nm and under fluorescent illumination."
......"Fig 6 shows the action spectrum for Cl influx, expressed in the same way as the results in Figs. 2 and 4. The red and blue peaks, the green trough and the rapid decline on the long wavelength side of red peak, are all quantitatively similar to these features of the photosynthetic action spectrum shown in Fig 2. "
The above paper was also attempting to make correlations with these ions (influx/efflux) and their dependency on PSI and PSII systems; however the tests they ran are very specific to the question asked in the op. From what was shown or referenced (P, K, Cl); all the elements had influx saturation equal regardless of wavelength. As well, in all cases the influx percentages (over wavelengths) matched photosynthetic actions spectrum. Smaller but noteworthy is that saturation intensities for each of these ions (related to influx) was much lower than the total CO2 saturation intensity (@448,680) wavelengths.
Though not all elements have been done in this way; one could conjecture that other ions would follow similar suit if they are easily translocated / moved / uptaken. I.E. it does not appear that spectrum "in itself" can "alter" (per se) certain ions over others; nor that spectrum may even play a role directly. The evidence presented there would tend to lead to the assumption that the typical chlorophyll action spectrum would also compare with relative influx amounts of these ions too.
Thinking about this, I suppose it does seem rather logical as action spectrum is already so limited in terms of high productivity bands and that further limiting certain ions in specific nm ranges would also require more intricacy of internal design.
So, now we are still left with obvious variations seen with MH / HPS bulbs and that in certain circumstances (HPS / LED) Mg and Ca may be needed in higher quantities along with "possibly" P. How the heck can we resolve these issues then, right? If in fact spectrum isn't playing the role, what is?
Well if you've read up until now, at least the variation in MH/HPS can reach some level of theorization. If we consider that HPS has a higher level of both 680 and 700 nm than MH; then part of this difference could very well be related to "emerson enhancement effect" (EEE) above. The HPS could "Drive" PSI specifically along with PSII more effectively than an MH bulb. As a result of this there should be proportionally higher ATP and NADP synthesis in HPS lamps. As well the higher overall PPD of HPS in these spectra will also be likely to introduce "cyclic flow" via PSI while waiting on further NADP (calvin cycle not related to light). Both of these components would serve to possibly increase the demand for P vs MH bulbs. Most decidedly at least HPS will have a greater effect with PSI / PSII and likely EEE.
In order to look at increasing requirements of Ca and Mg; we must look into the realm of "photoinhibition" (wiki)
Yup. a response from too much light (though again consider saturations and wavelengths from the paper above). Now this is not necessarily what you might think, e.g. bleaching or burning etc. It seems that some level of photoinhibition is quite common and plants have several means of adapting to various levels of "excess" intensities.
Note from the wiki that "Photosystem II is damaged by light irrespective of light intensity."
Also at this point there is another component that needs to be known / considered too; That is the "Xanthophyll Cycle" (Wiki)
Xanthophylls are accessory or antennae pigments (along with carontenes), that most notably are utilized in the "non-photochemical quenching" (NPQ). (Wiki)
Here is another paper. (Paper) It does a good job at showing visualizations of energy transfer from xanthophylls, action spectrum of these antennae along with a good final representation of the "Z scheme"
(with that paper also notice the structure of chlorophyll a/b and that the both contain Mg in their centers.)
There are several stages of plant responses to excess photons (including total or specific wavelengths) that become increasing larger or more dramatic, with respect to the amount of excess.
Here is a simple image that does well at showing various steps; View attachment 480998
Also a quick quote from the paper (doesn't need linked really) "Plants can try to protect the photosystems from too much light and avoid photoinhibition, by dissipating energy in form of heat. If heat dissipation can’t cope with protecting the photosynthetic apparatus and, toxic species, like superoxide (O2-), singlet oxygen (1O2*) and hydrogen peroxide(H2O2), start to be produced through the joint of excited chlorophyll and molecules of oxygen, other protective mechanisms are needed. Carotenoids suppress the excited state of chlorophyll and releases energy as heat. Xanthophylls (violaxanthin, antheraxanthin and zeaxanthin), which are, as well, carotenoids, have a protective role when the photosynthetic apparatus is exposed to too much light. This cycle converts violaxanthin into zeaxanthin under high light, and large amounts of zeaxanthin retards the damage of the D1 protein (Alves et. al , 2002)."
The first and weakest method of dealing with excess photon influx is via Heat production (video at the top also pointed to heat generation points). This is also where we begin to see Ca come in to play. (Paper) "TRANSTHYLAKOID ApH. The most rapid response to excess light is the increase in the rate constant for thermal energy dissipation from the PSII antenna and/or reaction center (kheat) associated with the development of the transthylakoid ApH gradient (141). The mechanismof this affect of increasing ApH is uncertain, but may involve aggregation of LHCI~ particles, facilitating increased kheat in the antenna (61) Alternatively, or in addition, the pH change may cause a reversible inactivation of the PSII reaction center involving loss of Ca and increasing kheat at the reaction center (142)."
The next process triggered to avert production of "reactive oxygen species" (ROS) from excess photons, comes about from the Xanthophyll Cycle. "A more profound change in PSII can be inferred from changes in fluorescence yields and q~ associated with the epoxidation state of xanthophyll cycle intermediates in both higher plants (28, 29) and algae(100, 101). The xanthophyll cycle in higher plants and green algae consists of conversion of the diepoxide violaxanthin to the epoxide-free zeaxanthin, via the monoepoxide antheroxanthin, when light absorption exceeds photochemical utilization. Epoxidation back to violaxanthin through antheroxanthin occurs in darkness or when light absorption is no longer in excess."
Also from this paper we can relate when damage does occur to PSII systems; where it is likely to occur or what area it will act upon. "Early research into mechanisms of photoinhibition noted an associated loss of the D1 32kDa-PSII reaction center polypeptide............ Subsequent studies associated damage and loss of D1 with slowly reversible photoinhibition, and there is now consensus that when photoinhibition involves damage, D1 is the first site to be affected (105). Among the chloroplast-encoded polypeptides, D1 shows the most rapid turnover, even in low light (73), with an estimated tl/2 of approximately 2h (134). Photoinhibitory loss of D1 should only inhibit photosynthesis if the rate of repair fails to keep pace with the rate of damage."
....... "The extent of photoinhibition will not only depend on the rate of D1 damage, but also on the rates of migration of the damaged and repaired PSII within the membrane, degradation of the damage D1, and synthesis of new D1. All these factors can contribute to the extent and rate of recovery from photoinhibition and may explain part of the interaction between photoinhibition and other environmental variables, particularly with respect to recovery where replacement of D1 is necessary to restore the pool of PSII."
......
"It therefore seems likely that the xanthophyll cycle is a, or the, major initial mechanism of decrease in PSII efficiency in sun leaves, and a first line of defense against PSII over-excitation during absorption of light in excess of photochemical utilization (29). Evidence of increased capacity for both D1 synthesis and xanthophyll cycle activity during acclimation to high light, indicates that both are probably critical to surviving excess light.
Shade plants appear to have a much lower capacity for xanthophyll cycle-related thermal energy dissipation (29) and for D1 repair (102, 138). observation is paralleled by the situation at low temperatures, where enzyme activities within both the xanthophyll and Dl-repair cycles will be limited (55, 106).
With the above we can see that heat production (resulting in Ca loss) and the xanthophyll cycle, though initial, are not able (nor designed) to eliminate destruction and repair of the D1. Also, that the overall negative photoihibitory effect (since D1 cycling is always occurring) is related to a plants' ability to both restore D1 and to prevent it's initial degradation. I read so much and I'm not sure if one of these links will contain it; however it should be noted that, plants are always trying to achieve a 1:1 equilibrium with destruction and repair of this D1 in PSII.
So then what are contributors to help reduce this destruction and repair?
This brings us to another paper. (Paper) "Overcoming photodamage to PSII for photosynthetic organisms is the rapid and efficient repair of the damage, which requires the synthesis of these proteins de novo. Thus, identifying mechanisms to accelerate the repair rate of thylakoid proteins under excess light conditions is of great importance."
........
"It has been reported that Ca2+ improvement of photosynthesis is related to enhancing the activity of antioxidant enzymes to alleviate reactive oxygen species (ROS) accumulation ( Zhao and Tan 2005; Tan et al.2011). The decrease in intracellular ROS contributes to the protection of PSII proteins to alleviate the photodamage under light and salt stress ( Al‐Taweel et al. 2007) because high ROS levels could suppress the synthesis of the D1 protein and almost other proteins (Nishiyama et al. 2001, 2004; Allakhverdiev and Murata 2004). Thus, the protein‐synthetic machinery may be a specific target of inactivation by ROS during photoinhibition. It can be speculated that exogenous Ca2+ may play a role in protecting the subunits of PSII reaction centers from photoinhibition by reducing the generation of ROS. Additionally, it has been reported that the Ca2+ could stimulate the rate of electron transports on the acceptor side in PSII (Seminet al.1998);"
......
Ca+ treatments contribute to the increase of the xanthophyll cycle‐dependent energy dissipation (NPQ) (Figure 2) and attenuate PSII photoinhibition (Yang et al. 2013). The decrease in qP was accompanied by marked increases in NPQ, and the increases in NPQ may accelerate the repair of PSII without significant effects on photodamage to PSII (Sarvikaset al. 2006; Takahashi et al. 2009).
....
The efficient ROS scavenging could reduce the damage to membrane lipids, enhance the repair of PSII, and sustain the photosynthetic properties. The increase of antioxidant enzyme activity can be considered as an essential mechanism in the cellular defense strategy against oxidative stress (Shi et al. 2006). In the present study, Ca2+ treatments could have helped to scavenge ROS by inducing the increase of activity of some antioxidant enzymes, for example, APX, SOD, and CAT (Table 1). The lower ROS accumulation resulted in slight damage to cell membranes of Ca2+ ‐treated seedlings (Figure 3) reflected by MDA and ion leakage, which are commonly considered as indexes of membrane damage or deterioration (Kwon et al. 2002; Yabuta et al. 2002). Therefore, exogenous Ca2+ seems to play an important role in alleviation of oxidative stress and damages to cellular components such as membrane lipids.
...
Under heat and HI stress, the more PSII dimers and monomers in the Ca2+ ‐treated seedlings suggested that Ca2+ may provide stability to these protein complexes. That is to say, Ca2+ may play an important role in the maintenance of PSII activity under heat and HI stress (Figure 4).
...
When ROS were eliminated by AsA, the lower portion was concluded to be caused by Ca2+ deficiency, and it could be indicated that Ca was involved in the protein repair process of PSII photo-inhibition.
....
As a second messenger in plants, Ca2+ plays a pivotal role in thesignal transduction pathway under abiotic stress.
Further information about Ca and PSII photoinhibition is included here: (Paper)
(pg. 405)
"In the thylakoid, calcium ions are necessary for the function and structural assembly of the oxygen-evolving complex (OEC) of phototsystem II (PSII). The PSII OEC is a multimeric complex in the thylakoid lumen responsible for light-dependent oxygen evolution in plants. Functional assembly of PSII and OEC requires that all essential polypeptides and cofactors are present in the stroma, thylakoid membrane or thylakoid lumen. "
"Therefore, both the initial assembly of PSII and its subsequent reassembly after photoinhibition require calcium availability in the thylakoid lumen. Furthermore, Ca++ in the thlyakoid lumen has been implicated in the stabilization of the high redox potential form of cytocrhrome b-599 (McNamera and Gounaris, 1995). All of these processes require the availability of Ca++ in the thylakoid lumen.
As can be seen from the previous section along with the above, that calcium is involved at many levels of photoinhibition with PSII. This includes the heat stage, xanthophyll cycle, ROS NPQ; as well as its' role in reducing D1 decay along with expediting recovery. It would seem reasonable to surmise that seemingly higher calcium requirements of plants, upon exposure of certain light sources (HPS LED) above saturation levels; could very well be related to the "level" of destructive photoinhibition being higher with these sources versus daylight. E.G. at the very least from higher levels of NPQ in the xanthophyll cycle, but more probably and increase in the D1 "cycling" of PSII resulting in increasing Cystolic Calcium demand.
Now we have theorized about P (some) and Ca, but this still leaves the evidence (specifically with LED's) of increased Mg demand. To discern where and how increased Mg might come into play, we have to look now at Photosystem I (PSI).
A good starting point is here (Paper) "Considering the factors to induce the inhibition of PSI, i.e., light, oxygen, and the input of electrons from PSII, it is natural to assume that the reactive oxygen species brought about by the reduction of oxygen is the direct cause of inhibition. One-electron reduction of oxygen produces the superoxide anion radical, which could dismutate and be converted into hydrogen peroxide. In the presence of reduced metal ions, hydrogen peroxide is converted to hydroxyl radical, which is highly reactive and destroys biological components within the diffusion limit (Asada, 1999).
......
"The addition of hydrogen peroxide during illumination of thylakoid membranes, however, caused the complete loss of the photooxidation of P700 (Sonoike et al., 1997). These results suggest that the photoreduction of the iron-sulfur centers on acceptor side of PSI by light illumination is the key to the problem. Hydroxyl radical, a most reactive species of active oxygen, is usually generated by a reaction between hydrogen peroxide and a reduced metal ion in a process called the Fenton reaction. It is plausible to assume that the hydroxyl radical, which is generated by the reaction between hydrogen peroxide and photoreduced iron-sulfur senters, destroys PSI at the site of production of hydroxyl radicals. "
--A note here to help, remember the beginning papers talking about PSI cycling and its' containing compound Ferrodoxin (an Iron- sulfate compond).
"P700, the reaction center chlorophyll of PSI, could be destroyed under high photon flux densities (Terashima et al., 1994)."
...
"Light-dependent fragmentation was also reported in wheat chloroplasts for the large subunit of Rubisco (Ishida et al., 1997,1998). .......... The degradation of Rubisco is also observed in the exposure of the protein to a hydroxl radical generating system (Ishida et al.,1999), and the site of cleavage was around the active site of they enzyme (Luo et al., 2002). These results indicate that Rubisco is inactivated by hydroxyl radical produced by the Fenton reaction between hydrogen peroxide and a reduced metal ion, both produced by photosynthetic electron transfer through PSI."
......
"Furthermore, fragmentation of Rubisco was also reported upon the light / chilling treatment of cucumber leaves in vivo, a condition in which PSI is photoinhibited (Nakano et al., 2006). .........Rubisco itself does not contain iron, but several divalent cations including iron could bind they enzyme to activate it in place of magnesium (Christeller 1981) forming a metal-substrate complex at the active site of the enzyme (Branden et al. 1984). Since the site of cleavage of Rubisco in vivo was also very specific and might be near the active site of the enzyme (Nakano et al. 2006), it is tempting to assume that the iron, which is released from iron-sulfur centers of PSI to stroma upon photoinhibtion of PSI, binds to Rubisco in the place of magnesium and triggers the degradation of the enzyme"
From this we can see that damage to the PSI photosystem via destructive photoinhibition, likely leads to a significant decomposition of Rubisco. As well, that iron can take the place of Mg where otherwise needed (though leads to destruction too). So then we need to consider what role Mg may play with Rubisco.
It may help here to again refer to the "calvin cycle" (Wikibooks) "- Rubisco: For activity, it requires a bound divalent metal ion, commonly magnesium ion. By stabilizing a negative charge, the magnesium ion serves to activate a bound substrate molecule. It requires a carbon dioxide molecule other than the substrate to conclude the assembly of the magnesium ion binding site in rubisco. This carbon dioxide molecule is added to the uncharged ε-amino group of lysine 201 which forms a carbamate. Then, the negatively charged adduct binds to the magnesium ion. Although the formation of the carbamate will form spontaneously at a lower rate, it is enabled by the enzyme rubisco activase. Magnesium ion plays an important role in binding ribulose 1,5-bisphosphate and activating it to react with carbon dioxide. Magnesium ion and ribulose 1,5-bisphosphate bind together through its keto and adjacent hydroxyl group. The complex forms an enediolate intermediate through deprotonation. This reactive species couples with carbon dioxide and forms a new carbon-carbon bond. Including the newly formed carboxylate, the product is coordinated to the magnesium ion through three groups."
Activation of calvin cycle
"Regulation occurs when the stromal environment alters by the light reactions. pH increases in the light reactions and concentrations of magnesium ion, NADPH, and reduced ferredoxin. These changes help couple the Calvin cycle to the light reactions. Specifically, rubisco gets activated when the concentration of these molecules increases and the pH increases. Activity of rubisco increases because light creates the carbamate formation which is a necessity in enzyme activities. In the stroma, when the concentration of magnesium ion increases, the pH also increases from 7 to 8. From the thylakoid space, the magnesium ions are released in order to create the influx of protons into the stroma. Carbon dioxide is added to the rubisco’s deprotonated form of lysine 201 while magnesium ion is bound to the carbamate in order to generate enzyme’s active form. Therefore, the light generates the regulatory signals, ATP, and NADPH."
Another paper talks further about Rubisco (Paper) "To be functional, Rubisco requires prior activation by carbamylation of the ε-amino group of active-site Lys201 (Lorimer and Miziorko, 1980) by a CO2 molecule, which is distinct from the substrate-CO2. The carbamylated Lys201 is stabilized by the binding of magnesium ion to the carbamate."
"One of the key players in the reaction catalysed by Rubisco is the magnesium ion. Apart from the carbamylated Lys201 which provides a monodentate ligand, the magnesium ion is liganded by two (monodentate) carboxylate ligands provided by Asp203 and Glu204 (Fig. 3) and three water molecules (Andersson et al., 1989). RuBP replaces two of these water molecules. For the reaction to proceed, a tight control of the charge distribution around the metal ion is crucial (Taylor and Andersson, 1997a) and this presumably also includes residues outside the immediate co-ordination sphere."
......
"CO2 replaces the last Mg2+-co-ordinated water molecule and adds to the enediol directly without forming a Michaelis complex (Pierce et al., 1986; Mauser et al., 2001). The resulting six-carbon compound, 3-keto-2′-carboxyarabinitol-1,5-bisphosphate is relatively stable and can be isolated (Lorimer et al., 1986)."
Other information (not all specifically related) about Mg can be found also and is of some note for awareness. (wiki)
"For example, ATP (adenosine triphosphate), the main source of energy in cells, must be bound to a magnesium ion in order to be biologically active. What is called ATP is often actually Mg-ATP.[4] As such, magnesium plays a role in the stability of all polyphosphate compounds in the cells, including those associated with the synthesis of DNA and RNA."
........
"Within individual plant cells, the Mg2+ requirements are largely the same as for all cellular life; Mg2+ is used to stabilise membranes, is vital to the utilisation of ATP, is extensively involved in the nucleic acid biochemistry, and is a cofactor for many enzymes (including the ribosome). Also, Mg2+ is the coordinating ion in the chlorophyll molecule."
........
"Thylakoid stacking is stabilised by Mg2+ and is important for the efficiency of photosynthesis, allowing phase transitions to occur.[69]"
It can be seen then, that Mg plays a critical role with Rubisco activation / catalysis; along with the requirement of Mg thylakoid levels as well as stabilizing intermediary products. From this we could theorize that destructive photoinhibition of PSI, leading to a destruction of Rubisco; would increase Mg utilization and probably necessitate higher concentration levels in these localized membranes. With the last set of quotes, it is also seen that Mg is required for ATP to become active. Further (though not specifically covered) "thylakoid stacking" is one possible response of plants to reduce photoinhibtion and, as well, is shown to require Mg for stabilization.
---------------
In conclusion, it would seem very practical and probable that;
- Efficient activation and optimization of both PSI and PSII systems can optimize photosynthetic processes (at levels lower than destructive photoinhibition) and thus indirectly increase P utilization; required for ATP and NADP along with ATP cycling. This effect would be most notable with PPD's at or near saturation levels and inclusive of red and far-red (680 & 700). (e.g. HPS vs MH)
- Photoinhibition and more specifically destructive photoinhibition of PSII via exceeding saturation levels of PPD (relative to photosynthetic activity rate) are likely to cause an increase in Ca utilization in efforts to avert or expedite destructive damage to D1 in PSII. This effect would be most notable with overall high PPD levels above saturation below 700nm. (e.g. HPS > Ca than MH)
- Photoinhibition and more specifically destructive photoinhibition of PSI via exceeding saturation levels (relative to photosynthetic activity rate) are likely to cause an increase, probably large, in Mg utilization as a result of damage to Rubisco, requirement for subsequent synthesis, possible damage to ATP or chlorophyll as well as an effect of Thylakoid stacking in efforts to reduce photoinhibition. This effect would be most notable with high PPD levels above saturation and above 680 nm (e.g. LED)
Light intensity affects photosynthetic carbon (C) fixation and the supply of carbon to roots. To evaluate interactions between carbon supply and phosphorus (P) supply, effects of light intensity on sucrose accumulation, root growth, cluster root formation, carboxylate exudation, and P uptake capacity were studied in white lupin (Lupinus albus L.) grown hydroponically with either 200 µmol m –2 s –1 or 600 µmol m –2 s –1 light and a sufficient (50 µM P) or deficient (1 µM P) P supply. Plant biomass and root:shoot ratio increased with increasing light intensity, particularly when plants were supplied with sufficient P. Both low P supply and increasing light intensity increased the production of cluster roots and citrate exudation. Transcripts of a phosphoenol pyruvate carboxylase gene (LaPEPC3) in cluster roots (which is related to the exudation of citrate), transcripts of a phosphate transporter gene (LaPT1), and P uptake all increased with increasing light intensity, under both P-sufficient and P-deficient conditions. Across all four experimental treatments, increased cluster root formation and carboxylate exudation were associated with lower P concentration in the shoot and greater sucrose concentration in the roots. It is suggested that C in excess of shoot growth capabilities is translocated to the roots as sucrose, which serves as both a nutritional signal and a C-substrate for carboxylate exudation and cluster root formation.
Phosphorus deficiencies can be due to Temperature, Environment, and Magnesium (. Higher elevated leaf temp causes the stomata to close, reducing transpiration, which reduces water usage. This in turn slows growth and phosphorus deficiencies have been seen under this stress. As well as under colder stresses when the soil temp drops below 60deg. the colder temp affects root extension and soil phosphorus uptake- warming tends to help. Now if your plant grows beyond the necessary pot size, it depletes the usable phosphorus in the soil and becomes starved of that basic element, causing a notable deficiency. Magnesium regulates uptake of the other essential elements and serves as a carrier of phosphate compounds throughout the plant, so a phosphorus deficiency will usually follow a Magnesium deficiency (CaMg).
SensiCloud is correct stating that HPS promotes increased Ca and P uptake.
Not sure if this was stated earlier, but medium is important as well. Coco binds with Ca ion.
Being that I'm growing in coco and was using HPS, i think it's safe to say that I didn’t have enough P which made Ca unuseable which also started affecting Mg absorption. We'll see soon! Today marks day one of 12/12. I started supplementing 2 mL/gal of BotanicareCalMAg... Probably should note that I switched base nutes to AN Sensibloom A and B when I noticed the deficiency. I did this because I thought the red stems were due to K def and AN has a lot of K in it.
Not much of an update but nevertheless, here they are tonight. Put them back under 1k hps and new growth is green again. I’ve been focusing on keeping my environment in check before messing with my nutrient mix. I re-read the info on the head formula and got my Mg up and K down and the plants seem pleased. I’m learning that she needs a lot of P. Right now my ppm ratios look roughly like this n-p-k-c-m-s (100-105-110-100-65-60) and I’m feeding twice a day now. In the full swing of things I plan on feeding 4 times/day.
Oh yeah, forgot to update. As of yesterday I’m feeding 3 times/day now. Every 8 hours seems to keep the coco evenly saturated right now. I’ve got the drain to waste part down but what’s the point if I’m not fully utilizing coco’s properties. I read some posts of @EventHorizan and @Wisher619 that you treat it much more like hydro than I originally believed. I knew it was hard to over water rooted plants but I didn’t know how easy it was to underwater them. The effects were subtle in my case but it was part of the cascade that was causing my deficiencies. Oh well, knowing this now will save me veg time next run lol.
