Phytochrome/Infrared Interaction

I don't know if this is relevant, and I haven't checked any of my books, but I thought the hormone, maybe florigen, was always produced by the plant, and destroyed by light. Admittedly, what light I don't know. But anyway, with the uninterrupted hours of darkness the hormone acumulated to a level that signaled flowering, and as long as each night that level was reached, the plant stayed in flowering without interruption.

Hey kief, what about the studies that say decrease in yield with more than 12 hours light? I haven't seen those. Personally, I give my plants as long a day as possible, while keeping them flowering.

HTH

I'dlike to read these studies too. It doesn't seem logical that giving a plant a longer time to photosynthesise during flower causes a lower yield.

From what i've read about phytochromes, scientists can only recognise 5. Phytochromes also only react to red light, cryptochromes and phototropins react to blue.

So if phytochromes are responsible for flowering, why is it that we can flower under just blue?

phytochromes are responsible for many things, the same can be said for phototropins and cryptochromes.

I forgot to mention that there is also a phytochrome that only reacts to the dark. Could this be the florigen you are speaking of?

I think flowering under "just blue" is a function that it might not be "just blue" that just as in the UVB for MH lights there is some.....is it that there may be some red in the "just blue"?

Yes, maybe... but some red is not enough red. It would still mean that the cryptochromes and phototropins would be doing all the growing.

Phytochromes determine a lot of factors, like the plants growth patterns... and if we veg' under red and veg under blue we can see that there are different growth patterns. the main thing I noticed was the leaves, under the blue the leaf edges are more rounded, and sharper under the red. Even the texture of the leaves was different and the colour too. The plants under the red had a darker green, whereas under the blue they were lighter and of a more intense green.

Also, IR actually reverses the growth effects of red light. So to intensify the IR in your grow area should only amount to stunted growth, particularly during flower and flowering beneath a HPS.

Yet, if IR reverses the effects of red light then the same can be said of blue light, in that it reverses the growth effects of red. Yet in this reversal do we assume that the plant stops growing? or merely displays new growth patterns? Is the transition as smooth as that? It would appear so...

I found this the other day that has been instructive for me....

tahoe58 said:

I found this the other day that has been instructive for me....

Click to expand...

Thanks tahoe... so the carotenoids do not respond to red light. The chart also shows that plants respond to green light.

Yet green light does not interrupt flowering, at least this is what is said. So if cannabis can still photoynthesise under green light, how is it that we can switch on a green light (not that I do) during flower, and not interrupt the cycle?

thats a good question....I do not know the answer...and will think about this a little more now....

I feel the chart also shows that IR is not a good idea. The plant reflects what it can, to increase the IR and force the plant to take in more than it can could do some cell damage.

Heat is something that we are always concerned about, I don't think it's a good idea to put in any more. even during lights out, unless it's too cold of course, then some heating may be in order.

I'm wondering where that chart came from. It is a basic truth, but far from complete. Different wavelengths within a light spectrum actually trigger different metabolic pathways. I studied this last semester. I'm pre-med majoring in Clinical Lab Sciences. Each chlorophyll has many molucules inside that need energy to work, energy in the form of different wavelengths of light depending on which molucule it is. Green light is not absorbed AT ALL but entirely reflected. That's why a green light will not interrupt the dark photoperiod. Wavelengths from 650 nm to 700 nm affect phytochromes, of which there are 5 known, and different plants have different numbers, cannabis has only two, Pr (phytochrome red) and Pfr (phytochrome infra-red). Yellow has little, but some effects on photosynthesis, the molecule if affects I'm not sure. What I am sure is there must be a balance of the lights spectrum. Henk, owner of Dutch Passion Seeds, tells us that a heavy blue spectrum during vegetative growth increases probability of female characteristics. But even a blue light has microamounts of the rest of the spectrum. If you tried blue LED, your plant will die because LED is wavelength specific and does not produce color outside it's specific spectrum. Pr responds to red light present and converts to Pfr. Pfr is, to my knowledge, completely inert and will not trigger hormones, but it does create a biological clock for the plant to know what season it is based on how long the light stays present. Once the light is gone, there is no red light to change Pr to Pfr and Pfr changes back to Pr triggered by infrared light, what we feel as heat, which is always present. Long days does not allow a critical amount of Pr to accumulate at night. I have heard some experts say that florigen is constantly produced, but that the long days do not allow for enough florigen buildup to actually see the results. Some experts say that phytochrome will only trigger the production of florigen with critical amounts of Pr after a long enough light period. I think the latter is more likely. It makes more biochemical sense when one understand metabolic pathways within living organisms.

For SkunkKushybrid:

The plant reflects nothing but green light. It absorbs all other light and in fact has the abillity to take in more than we can dish out. Little Big Way, winner of the 2005 Toker Bowl, grew an 8 foot Afghan Dream with a yield of 4 pounds. He used 4x 1000w Metal Halides on that one plant. We will not cause cell damage by a 5- 10 degree increase at night, especially if the daytime temperature is maintained at 65 or 70. Caretenoids do not respond to red light, but to Blue and Ultra Violet light (between 450nm to 500 nm). Some have debated the importance in UV light. Metal Halides have abundant amounts, but are weaker on the red spectrum. High Pressure Sodium is much stronger on the red spectrum, i.e. why it's a flowering favorite, but has no UV light. Ed Rosenthal sees little difference in yield between the two, but UV light has been proven to increase bud density, if not yield. For this reason, Jorge Cervante suggests a 2MH/1HPS ratio, or a 1/1 ratio for best results.

Yes thankyou... my head's alittle fuzzy today with it being New Years day.

All this does though is explain basic photosynthesis in a more scientific way. Increasing the heat in the flowering area during lights out just doesn't seem like a good idea to me, at least not for my grow space. I'm sure they (the plants) enjoy a nice temp drop during the night. Also this heat would need to be accounted for. Greater attraction to insects for example, mould...

Also one other point, the DP thing... where the guiy says that blue light will make a plant display more female characteristics. What does this mean? That it will still be a male plant but grow like a female?

This doesn't make sense with most seed grows that i have done. I only got caught out once and it was a biggy. The whole crop was the reverse, all the males were female and all the females were male (only 5 plants). What I mean is that usually from the way the plant grows I can tell whether it is male or female from fairly early on. Obviously there are exceptions, but as a generalisation i can tell male from female by growth patterns. There's a reason for this. Males will need to grow taller than females for two reasons that i can think of, the wind and gravity. When the wind hits the pollen gravity will soon take it's place and the pollen will fall downwards. The females are shorter to receive it.

Yes by using light we can alter a plants growth characteristics but I can not believe that this could also cause a plant to display opposite sex characteristics...

Is this DP thing you are referring to do with the work they did on feminised seed?

hey Skunk.......just curious why you say this?

skunkushybrid said:

........ I'm sure they (the plants) enjoy a nice temp drop during the night. ......

Click to expand...

kief....I'll have to go back and dig up the context of that figure. I'll be back if/when I can pinpoint it again....loved your discussion, hihghly helpful for my ole brain! hahahahaha thanks.

Good question... uhm, I think it's because I like a temp drop during the night. I cannot sleep with heating on in my bedroom, and I must have the window open, a tiny crack even in Winter.

Too cold is bad too of course... but I believe that a 10f drop during the night may provide more benefit. Who knows, we need to remember that there are are lots of things scientists still don't know.

I mean to concentrate our efforts on phytochromes may not be the right direction. Yes we may get increased yields per plant which would be good for commercial growers, but as a hobby grower (and enjoyer of the fruits) I'd rather concentrate on potency, the yields will take care of themselves.

I'd also like to read the paper that says cannabis has only one, albeit interchangeable, phytochrome.

There is a phytochrome that only reaches critical levels during the dark... and is destroyed by light. Now that sentence rings a lot of bells in my head.

Just thought I'd do a little reading, and I typed this into google: cannabis phytochrome

cannabis phytochrome - Google Search=

This thread is top of the page.

Here's a link to the second on the page...

MARIJUANA OPTICS: An elaboration on the process that makes THC

Done by a guy calling himself Joe Knuc. Fairly interesting read on UVB too.

hey Skunk, that's the source work for the original comments made by YGF....gee....I guess its almost a couple of months ago now already eh? wow how time flies.

I am now confuzzled....reference has been made to 5 phytochromes (PhytoA, B, C, D, E), that respond to light/dark. there is some redundancy, but also uniqueness particularly in their absorption spectra. now this is where I get confused, as I understand it each Phyto has two forms (pf anfd pfr). it has been referenced that cannabis has only one phytochrome?

I found this. the molecular biology and biotechnology of flowering (2005 second ed.) - chapter 1 - photoperiodism and flowering......I am reading this now....hopefully, I will unconfuzzle myself....

The idea that cannabis only has one phytochrome was from an AskEd column from Ed Rosenthal on CannabisCulture.com in September 2005. He detailed the effects of red/infrared light and it's effects on phytochrome. It's what originally prompted my question of raising temperatures at night. I'm in the middle of my experiment, but won't see the results for another month or so. For that reason I called on others with this thread to bounce ideas and maybe getting other experiments started. Some research in my botany book referenced five different types of phytochrome, but that different plants have different numbers. It gave an example of two species of pea pods, one had 3 phytochromes the other had 5. Ed Rosenthal only referenced the one type, and I have not come across anything that contradicts him yet. I've seen a lot of people make the assumption that plants will like something because they do. Like sleeping at night. Jorge Cervantes even admits to believing this at first, but his Medical Grower's Bible on page 38 states, "I used to believe a point of diminishing returns was reached after 18 hours of light, but further research shows that vegetative plants grow faster under 24 hours of light." One of our forum members admitted to believing that plants needed sleep cause he did. What I have done is set small ceramic space heaters with a digital temperature set for 75 degrees at night. I try to maintain 70 degrees during the day and am pretty successful at maintaining it. The space heaters kick on at night at keep it slightly warmer. I live in an arid climate and humidity isn't a problem for me. I've just induced flowering simoultaneous with this experiment. The downside is that my control groups were previous crops, I don't have enough room to run simoultaneously an experiment and a control group. I'll have the results starting in a month all the way through harvest.

As far as the Dutch Passion goes, that info was from DUTCH-PASSION, among the archives. Jorge Cervantes adapted it into his book, and lists ways to promote feminine growth. That is, at a certain point in a plants life, sex is determined and it's not at pollination. Jorge Cervantes adds this, "Environmental factors start influencing sex the moment the seedling has three pairs of true leaves (not counting cotyledons)." p. 20 In response to light, he says, "More blue light increases the number of female plants, more red light increases male tendencies."

You said you were more concerned about potency than yield. You should actually consider this approach, then. Research shows that stress on plants may decrease overall yield, but may substantially increase resin production. This is seen with experiments using higher elevations, increased UV production, outdoor stress, water availability. The ability to breed for outdoor and indoor strains has eliminated much of the differences in resin production. It is mostly genetics, but environment can play a strong factor in a higher resin production.

Ok, found the page.

• a higher nitrogen concentration will give more females.
• a higher potassium concentration will give more males.
• a higher humidity will give more females.
• a lower temperature will give more females.
• more blue light will give more females.
• Fewer hours of light will give more females.

It is important to start these changes at the three-pairs-of-leaves stage and continue for two or three weeks, before reverting to standard conditions.

Here's the link:
DUTCH-PASSION

wow...thats cool.....thanks for sharing that Kief! cheers!

That article is about feminised seed. I read it around a year ago. Although the piece I read was much longer.

Also this still ignores cryptochromes and phototropins... also what evidence did Ed' supply to back up this 'fact'?