The Ideal spectrum.

jarvild

jarvild

Well-Known Member
ChiefRunningPhist said:
Ya that's true, no light no heat. I was hoping @jarvild would have noticed different leaf temps but perhaps NIR LEDs are reflected at 850nm(?), or more is needed? And lol thanks, I appreciate it, I need all the luck I can get :bigjoint:but same to you as well.
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So just and update on that experiment on leaf surface temp with the IR gun. Initial finds as suck but would like some observations from your end or anyone else wanting to contribute.

1, Ambient air temps @ 75 degrees F
2. top leaf surface @ 73.4 degrees F
3. Underside of leaf surface 88.7 degrees ( comment to follow)
4. Shaded underside leaf temp 80.2 degrees.

Comment on 3 is that was facing up at the bottom surface with the lights overhead, so it's either that the leaf doesn't absorb all the infra red radiation and allows some to pass through or the guns target field was wider than the leaf surface, That's why the shaded leaf test was done with a barrier between the light and leaf. All temps where taken a a 3" distance approx.
 
hybridway2

hybridway2

Amare Shill
jarvild said:
Add it up. 5k flower 2k veg, lets say an average 2.5 units per thousand @ $1,600 a lb.
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jarvild said:
So just and update on that experiment on leaf surface temp with the IR gun. Initial finds as suck but would like some observations from your end or anyone else wanting to contribute.

1, Ambient air temps @ 75 degrees F
2. top leaf surface @ 73.4 degrees F
3. Underside of leaf surface 88.7 degrees ( comment to follow)
4. Shaded underside leaf temp 80.2 degrees.

Comment on 3 is that was facing up at the bottom surface with the lights overhead, so it's either that the leaf doesn't absorb all the infra red radiation and allows some to pass through or the guns target field was wider than the leaf surface, That's why the shaded leaf test was done with a barrier between the light and leaf. All temps where taken a a 3" distance approx.
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Leaf temps have nothing to do with LedDefficiency. Sorry! Tried that.
 
ChiefRunningPhist

ChiefRunningPhist

Well-Known Member
OneHitDone said:
I personally call bs on a lot of the theory I read around here about leaf surface temp.
I had shared this somewhere before and it was kinda brushed off, you seem to have the knowledge to incorporate this info into your data set in some capacity.
This was on a sunny day approximately 70 degrees.
Leaf surface temp followed by soil temp at the bark below the plant.

View attachment 4395229 View attachment 4395230
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Interesting. The particular plant species could have some sort of protective layer (or just layer) that is reflecting much of the IR, or the leaves along with a breeze could be transpiring to cool themselves?

I got my IR gun after I transitioned to LED and never personally took HPS LST readings.

If the absorbance spectra is wide enough to include NIR/IR, then the presence of NIR/IR should have a thermal impact (750 nm+, up to 730nm-ish the radiation could contribute to chemical processes that may or may not be exothermic), whether or not that impact is mitigated by plant mechanisms or not, I can't say. Everything I've read says that higher IR leads to greater LST, and the science seems supportive, but I never personally tested.
 
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ChiefRunningPhist

ChiefRunningPhist

Well-Known Member
jarvild said:
So just and update on that experiment on leaf surface temp with the IR gun. Initial finds as suck but would like some observations from your end or anyone else wanting to contribute.

1, Ambient air temps @ 75 degrees F
2. top leaf surface @ 73.4 degrees F
3. Underside of leaf surface 88.7 degrees ( comment to follow)
4. Shaded underside leaf temp 80.2 degrees.

Comment on 3 is that was facing up at the bottom surface with the lights overhead, so it's either that the leaf doesn't absorb all the infra red radiation and allows some to pass through or the guns target field was wider than the leaf surface, That's why the shaded leaf test was done with a barrier between the light and leaf. All temps where taken a a 3" distance approx.
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Curious the underside being higher temp. I'm wondering if transpiration only takes place on the adaxial side (top).
smLeafOrientation.jpg
I'm trying to grasp how the shade avoidance mechanism works. If you have shade you have less light. But how do you increase your NIR in shade while decreasing the visible? It must be that NIR/IR is somewhat absorbed and somewhat passed through? If all of it passed through then the plant wouldn't be able to detect it, so some must be absorbed while some must be passed through? Then, in the instance a nearby plant covers the seedling with shade, the amount of visible is reduced (ie shade) but the amount of NIR/IR is less so reduced due to the partial transmittance of NIR/IR through the leaf? I think understanding this better would help try to determine what WV to use for LST manipulation, ect.


Just some rando...
Leaves that are healthy are mostly water. 1cm3 of water absorbs 3400× more energy than 1cm3 of air before raising 1°C. This means the air will heat up faster and cause the leaves to look as if they are "cooler." When the leaves become unhealthy and dry they get HOT. There's no more water to cool them. I've always noticed that leaf color effects its temp as well. Whether this is mistaken for low water content (low water content typically correlates with leaf discoloration) I'm unsure of, but I noticed if any leaves are showing less than green then I raise the lights and try to determine the problem. As soon as the leaves begin to shift in color they raise in temp. The raise in temp leads to more discolor which leads to higher temp, its like plant leaf thermal runaway lol but its something I've noticed. Next time you have issues, IR gun your shit leaves and then compare temps with your good leaves. I've noticed if I can keep my shit leaves temps down via periodic misting and raising lights that they will come back.
 
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nachooo

nachooo

Well-Known Member
Well..thats how shade avoidance works I have read about...Ratio or red/far red change cause Far red pass much more trought the canopy..so the ratio changes...and then ...the stem grows...As the spectometer confirms...
Greens also goes deep ...so maybe has some effect...
 
nachooo

nachooo

Well-Known Member
I remember to read and post here some time ago an study that tells Far red absorption changes in relation with air humidity...so the author teorized about Far red also signaling dry or humid conditions in order to close or open the stomata
 
Warpedpassage

Warpedpassage

Well-Known Member
nevergoodenuf said:
This might be some more interesting data. First pic is 3000k/90cri top of canopy and the second is under the canopy.View attachment 4395462 View attachment 4395463
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I have often wondered about this, well maybe not often. Thank u for posting this. Are we seeing the red shifts further to far red as the distance from the light source is increased? Im wondering if this same phenomena as we witness light from distant stars reach us but shifting to further red because of the distance it travels.

Is it possible to take readings in an empty room with different distances from light source? Again many thanks.
 
nachooo

nachooo

Well-Known Member
Warpedpassage said:
I have often wondered about this, well maybe not often. Thank u for posting this. Are we seeing the red shifts further to far red as the distance from the light source is increased? Im wondering if this same phenomena as we witness light from distant stars reach us but shifting to further red because of the distance it travels.

Is it possible to take readings in an empty room with different distances from light source? Again many thanks.
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Red does not shift....Red is almost all absorbed by the top of the canopy...far red is much less absorbed and goes trought the leaves to low zones..this is well studied in botany
 
lukio

lukio

Well-Known Member
ChiefRunningPhist said:
I like your breakdown, seeing a much lower P is more what I'm after. I just didn't know how much more K than P. After seeing your plants and looking at your recipe I think I'm going to be adding a lot more K2SO4 to the maxi. I added K2SO4 at the tail end of last round and it seemed to help, but it was hard to really pinpoint that as the sole reason.
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did you see renfros breakdown? blew my mind. crazy high Cal
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Screenshot 2019-09-17 at 14.08.19.png

i asked what scale he is on but he blanked me. im guessing 0.7
 
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coreywebster

coreywebster

Well-Known Member
nachooo

nachooo

Well-Known Member
jarvild said:
I wonder why the dip in yellow between the orange and green for under canopy reading.?
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Exactly at 580 nm...Nice you noticed that..I dont see that this wavelenght is specially important in anywhere...I mean photosynthesis graph...etc... however there is some kind of noticeable absortion....Which is phony is that..HPS is emiting hard at this yellow...maybe you are into something
 
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