The how to and why fors of CO2 supplementation for growers

[Lazyman]

Hey ST, I've read a couple grow journals where guys have staggered the lights so that each lamp runs for two hours, then its neighbor comes on for two hours, back and forth. THis way plants get 6 hours of intense light, and 6 hours of dim light per cycle, with apparently no reduction in yield or quality. I'm emulating this design in my new op and have high hopes. Does this method perhaps curtail the depression phenomenon you mention above?

 

[Lazyman]

Man a quantum light meter starts at about $200 (http://www.specmeters.com/Light_Meters/Quantum_Light_Meter.html) that measures PAR, gonna have to get one someday, but I'll still be one of only a couple guys here with them. Lumen meters are everywhere and cheap so thats what everyone uses for reference. Any estimates on how many PPFD a 1000W HPS puts out at 22" or so from the bulb?

 

[*mistress*]

how is the opening & closing of stomata measured by the gardener? accurately?
purely from rh readings?
those only accurate if room fully sealed & no intake-rh-influence... maybe.


https://www.icmag.com/ic/showpost.php?p=2158689&postcount=2:

rh/vapor pressure
relative humidity is an expression of the actual water vapor pressure, expressed as a percentage of the maximum water vapor pressure possible under certain air+atmospheric pressure conditions.

@ room temp (~60*f), 100% humidity exerts a vapor pressure of 24 torr (~4.65 pound-force per sq "[24*{19.337*10^-3}]=4.65 psi pound-force). >24 torr of vapor pressure exerted on leaves, and leaves sense a vapor pressure deficit.

leaves stomata opening/closing influenced by difference between internal/external vapor pressure. opening/closing of stomata regulates gas exchange+transpiration, which in turn regulates growth/fruiting.

vapor pressure deficit is a lack of water pressure upon plant. this would be a low rh. it is indirect measure of water loss from plant. as plant attemps to balance internal/external vapor pressures, they draw up more water from roots and transpire it into the atmosphere. hence the de-humidifiers used in gardens.

...
note: in general...
lower rh(high vpd)=increased transpiration, translocation, water uptake, greater calcium absorption/transport.

higher rh(low vpd)=slower transpiration, translocation, water uptake, slower evaporation, increased growth.

I have already figures out how to prevent "midday depression" and "multi-peaked Pn"... (ie. what you are referring to, sometimes called "noon-break phenomenon")....

...
Main Environmental Causes:

* VPD = when VPD is too high the stomata close decreasing stomatal conductance.

this means that stomata close when rh is low? maybe not...
they actually draw up & expel more when the rh is low... calcium is also better assimilated during lower rh... even though it mostly immobile.

high vpd = low rh... ieg, vapor pressure deficit. this what stomata prefer, especially if temps not over 80-85f, or so... they try protect cells over that temp, especially if rh too low... to conserve water...

however, if water available, they draw it up & out of plant... lowering the rh, directly, decreases the pressure gradient that the leaves 'feel'... this is actual weight of water vapor - that the plant must overcome to expel internal water.

How to Prevent Midday Depression:

* Lowish [sic] VPD = 0.8-1.3 kPa

that would mean higher rh... which, ok, as long as lots of air flow over canopy - & that same water-holding air extracted from garden. whether sealed, or lots of in+out...

* Soil-Water Status = keep media moist, do not let it go lower than about 45% moisture content (by wet weight gravimetric basis; see link in my sig for more info on how to water)

they like sub-irrigation... lots. this give top of media lots of oxygen, which roots like.

nice sub-topic... definitely variable of c02 uptake, as c02 also affect stomata... mini-ecosystem

 

[Enevold]

Does anyone know what order of magnification is necessary to see stomata?

 

[secondtry]

Hey ST, I've read a couple grow journals where guys have staggered the lights so that each lamp runs for two hours, then its neighbor comes on for two hours, back and forth. THis way plants get 6 hours of intense light, and 6 hours of dim light per cycle, with apparently no reduction in yield or quality. I'm emulating this design in my new op and have high hopes. Does this method perhaps curtail the depression phenomenon you mention above?

No I don't think that will mitigate midday depression in terms of DLI (Daily Light Integral; ie. total daily irrdiance). To stop midday depression you need to control VPD. However, using that method could reduce midday depression by cooling the leafs which effect VPD.

P.S. The method you suggest will lower Pnnet (net rate of daily photosynthesis), while it will lower elctricly cost I wouldn't suggest it...

HTH

 

[secondtry]

Does anyone know what order of magnification is necessary to see stomata?

You need a microscope. The least expensive you can get away with (while still a high quality microscope) is the "small" version sold by my friend MicrobeMan (see http://www.microbeorganics.com/#Microscopes_for_sale http://www.microbeorganics.com ) for about $300. I can post a how-to for measuring stomata (by micron).

 

[Lazyman]

Interesting, the latest journal I read yielded 3+ pounds using 1 lights worth of juice, the same as his control garden with two lights on full-time. So I take that to mean yield is not impacted negatively with that system, and comes with substantial energy and cooling cost reductions. I'll know if it works in a couple months!

 

[secondtry]

Man a quantum light meter starts at about $200 (http://www.specmeters.com/Light_Meters/Quantum_Light_Meter.html) that measures PAR, gonna have to get one someday, but I'll still be one of only a couple guys here with them. Lumen meters are everywhere and cheap so thats what everyone uses for reference. Any estimates on how many PPFD a 1000W HPS puts out at 22" or so from the bulb?

Don't waste you time with that toy, if your going to get a quantum sensor you need to get the LiCor LI-190 ( http://www.licor.com/env/Products/Sensors/190/li190_description.jsp ). That plus the data reader is about $1,000. The quantum sensor you list is crappy (I'm not trying to be rude, just honest).

Have you read the LED vs. HID thread I posted heavily in? If not I suggest you may want to, especially the last few pages where I and Avenger talk about light measurements and why PAR irradiance (W/m^2 or J/s/m^2), lumens and PPF (umol/s) are not what we want. We (at least) need PPFD (umol/m^2/s) which is found at the canopy. I have covered all these topics in the LED vs HID thread, all the info needed is there which may help you.

BTW: PAR watts is BS, that as touted by SunMaster is a joke. We want PPFD. PAR watts and PAR irradiance are not real terms, there is no standard term for W/m^2 or J/s/m^2 so often PAR irradiance is used.

In that link you offer they talk about PPF as if it's PPFD, and it's not. They should write PPFD, not PPF becuase PPF is measured as radiant photons (generally at the lamp) while PPFD is measured as irradiance photons (at the canopy). Both count photons within the PAR range (ie. 400-700 nanometers). That is why I don't like that company, they use the term PPF instead of PPFD. Also, Apogee is an even worse quantum sensor than the one you linked to.

I have very grand plans to test many lamps, reflectors and ballasts with the Li-cor and a spectroradiometer (once I buy one). With the spectroradiometer I will make my own SPD's of each lamp for real comparison between lamps. This is all detailed in the LED vs. HID thread.

In the LED vs HID thread I also write how KNNAs info (his spreadsheet, etc) is not valid.

HTH

 

[secondtry]

Interesting, the latest journal I read yielded 3+ pounds using 1 lights worth of juice, the same as his control garden with two lights on full-time. So I take that to mean yield is not impacted negatively with that system, and comes with substantial energy and cooling cost reductions. I'll know if it works in a couple months!

I wouldn't assume his/her results are applicable to other gardens, it has do to with the irradiance used (PPFD; Photosynthetic Photon Flux Density) and the DLI (Daily Light Integral). I think I would out yield a light the way you suggest vs. high PPFD all day long.

But the point about energy saved is a worthy goal for sure.

Yield and Pn are not linear, that is, increased Pn doesn't always equate to increased yield, but it does equate to increased energy and health of the plant which means less stress. And in cannabis increased Pn generally does mean increased yield and growth.

If in that grow log the grower is not measuring PPFD than you have no way to copy his/her results becuase you could have less PPFD than that person. That is why I suggest we need to start using PPFD, to make growing between gardens and gardeners more comparable.

All the best

 

[secondtry]

RE: measuring stomata:

Here are two sources of info to measure by micron:

1. “Microscope Micron Measuring,”
http://www.microscopy-uk.org.uk/mag/artdec99/cwnano.html

2. “Microscopy Scales: measurement in the micro-small world,”
http://www.microscopy-uk.org.uk/mag/articles/size.html
​

Here is info on measuring and qualifying leaf stomata:

Leaf stomatal measurements for testing stomatal openess and for polyploidy assays

1. “Structure of Leaves,”
http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/botany/leaves.html


2. “Leaf Stomata as Bioindicators of Environmental Change,”
http://www.accessexcellence.org/AE/AEC/AEF/1994/case_leaf.php


3. “How do I measure stomatal density?,”
http://www-saps.plantsci.cam.ac.uk/records/rec54.htm


4. “Stomatal impressions – some simple alternatives,”
http://www-saps.plantsci.cam.ac.uk/osmos/os20.htm#stoma
​

HTH

 

[secondtry]

Man a quantum light meter starts at about $200 (http://www.specmeters.com/Light_Meters/Quantum_Light_Meter.html) that measures PAR, gonna have to get one someday, but I'll still be one of only a couple guys here with them. Lumen meters are everywhere and cheap so thats what everyone uses for reference. Any estimates on how many PPFD a 1000W HPS puts out at 22" or so from the bulb?

Who else here using a quantum sensor? I am surprised anyone here uses one.

I have no idea how much PPFD is at 22" from a 1000w HPS because it depends upon the lamp (and it's age), the reflector and the ballast.

HTH

 

[Lazyman]

Like I said, given the price it's unrealistic to use PPFD for comparisons here, until the meters are $20 at hydro shops we'll all probably continue to compare lumens/footcandles because it's all we can effectively measure.

Thanks though, I trust that your science is sound!

 

[secondtry]

Hey bro,

I plan to test many lamps/reflectors/ballasts combos at a few different distances and ages of lamps (new and at 100 hours old). I plan to report my findings at my own site, just like Sanjay Yoshi Ph.D has done for reefing (I am copying his methods). That way anyone here can use my data as a 'ball park' method to find the PPFD their setup is emitting. I will start with my Hortilux Super HPS 600w with PL reflector and NextGen ballast, then I will do testing on CMH and then on to testing 1000w Hortilux Blue...and so on. I will also test LEDGirls new ~300watt LED array to put an end to the crazy claims of LED sellers.

I will start testing within the next two months. If you list the lamp, reflector and ballast you use I could test that too. I will contact many manufactures of products and ask they send me products to test on loan.

 

[Lazyman]

Excellent, I can't wait! Currently using Quantum 1KW ballasts, and Ushio HPS bulbs (no reflectors, hung vertically between plants.

 

[secondtry]

Oh hell bro...That's done and done!

I was planing on buying a Quantum ballast to compare it the NextGen anyway...and I had planned on testing the Ushio too. I think once I have tested a few lamps/combos I will send the results by email to companies who I want to test. I hope that will show them I am serous and trustworthy...

 

[secondtry]

Hey Mistress:

Mistress wrote:

2ndtry wrote:

I have already figures out how to prevent "midday depression" and "multi-peaked Pn"... (ie. what you are referring to, sometimes called "noon-break phenomenon")....

...
Main Environmental Causes:

* VPD = when VPD is too high the stomata close decreasing stomatal conductance.

this means that stomata close when rh is low? maybe not...
they actually draw up & expel more when the rh is low... calcium is also better assimilated during lower rh... even though it mostly immobile.

Yea a decrese in stomatal conductance means the stomata are less open. But RH doesn't equal VPD, thus RH can be fine and VPD could still be high if the leaf temp and room temp are wrong. You are correct the transpiration will increase with high VPD and that's not a good thing. We don't want a lot of transpiration, that's why keeping VPD around 1 kPa is good. Ca is immobile, it's not mostly immobile (unless you have references I can read?). I apply Ca via foliar (ORMI amino acid), not media drench. Adding Ca to media can cause lockout of other elements.

Mistress wrote:

2ntry wrote:

high vpd = low rh...

ieg, vapor pressure deficit. this what stomata prefer, especially if temps not over 80-85f, or so... they try protect cells over that temp, especially if rh too low... to conserve water...however, if water available, they draw it up & out of plant... lowering the rh, directly, decreases the pressure gradient that the leaves 'feel'... this is actual weight of water vapor - that the plant must overcome to expel internal water.

You lost me there. But yea, stomata are more open in VPD of 0.8-1.2 kPa.

Another factor of stomatal openness is spectral quality of the lamp, ie. the wavelengths emitted. I take this data from studies using Arabidopsis spp. (often Arabidopsis thaliana). Arabidopsis spp. is a member of the mustard family and its genome has been fully sequenced. Arabidopsis spp. is often used by scientists as a model-reference organism for other plants. Arabidopsis spp. is to plant biologists what the mouse is to mammalian geneticists.

• Blue light = opens stomata
• Green light = closes stomata (in the morning)
• Far red light = closes stomata

It was thought for a long time (and still is) that carbohydrates are the major player in stomatal opening on a biological/chemical level. But it turns out potassium levels in leaf could be a bigger factor and is the reason green light closes stomata in the morning.

And Co2 does have (a lesser) effect upon stomata in that low Co2 tends to open stomata and high Co2 close stomata (but less so then VPD and soil-water status and spectral quality)

References (not about Co2):

1. “Current theories for mechanism of stomatal opening: Influence of blue light; mesophyll cells, and sucrose,”
http://www.springerlink.com/content/k10v135008q4435k/


2. “Reversal by Green Light of Blue Light Stimulated Stomatal Opening in Intact, Attached Leaves of Arabidopsis Operates Only in the Potassium-Dependent, Morning Phase of Movement,”
http://pcp.oxfordjournals.org/cgi/content/abstract/pci249v1


3. “Blue Light and Phytochrome-Mediated Stomatal Opening in the npq1 and phot1 phot2 Mutants of Arabidopsis,”
http://www.plantphysiol.org/cgi/content/abstract/133/4/1522
​

HTH

 

[smurfin'herb]

nice thread

 

[supermanlives]

i quit using it.. my house has enough due to open flame natural gas heaters LOL, great thread

 

[racinj37]

Great thread. Can anybody chime in on how much faster flower time is when using CO2? I'm interested in hearing feedback as I am in my first run with CO2 at day 30 (12/12). The girls definitely seem to be maturing faster and growth is more vigorous than prior grows without the gas. Just want to know if you guys are actually cutting sooner with CO2 enriched environment.

 

[Lazyman]

Most seem to agree that flowering is about 5% faster with CO2.