Phytochrome and forced flower via spectrum alteration

Mr Celsius · Apr 9, 2008

Hi

I've been doing a bit of research about how to flower plants earlier in the season, as to beat the heat and rippers. I've already found my autoflowers, but I would like to be able to flower ANY strain early. This process would be good for very long flowering time Sativas, anyone who lives in a very northern area or just to get an early harvest.

I discovered this after looking at a thread about using red mulch/plastic with tomatos to increase yields... which was inconclusive. However, it did lead me to spectrum alteration within the plants to induce flowering.

Short day plants flower when there is more darkness (Mj)
Long day plants flower when there is less darkness (Lettuce)
Day neutral plants flower no matter what (autoflowers)

Lets start off with explaining what phytochrome is and what effect it has on the plant.

Phytochrome is a photoreceptor, a pigment that plants use to detect light. It is sensitive to light in the red and far-red region of the visible spectrum. Many flowering plants use it to regulate the time of flowering based on the length of day and night (photoperiodism) and to set circadian rhythms. It also regulates other responses including the germination of seeds, elongation of seedlings, the size, shape and number of leaves, the synthesis of chlorophyll, and the straightening of the epicotyl or hypocotyl hook of dicot seedlings.

Now how does it actually work:

"Photoreceptors and circadian clocks are universal mechanisms for sensing and responding to the light environment. In addition to regulating daily activities, photoreceptors and circadian clocks are also involved in the seasonal regulation of processes such as flowering. Circadian rhythms govern many plant processes, including movements of organs such as leaves and petals, stomata opening, stem elongation, sensitivity to light of floral induction, metabolic processes such as respiration and photosynthesis and expression of a large number of different genes."

In the following text, by exposing the plants to infrared light (730 nm) at darkness they were able to reduce the amount of light needed to induce flowering Cockleburs:

Experiments with the cocklebur have shown that the term short-day is something of a misnomer; what the cocklebur needs is a sufficiently long night.
# Cockleburs (adapted to the latitude of Michigan) will flower only if they have been kept in the dark for at least 8.5 hours — the critical period. (A and B).
# Interruption of an otherwise long night by light — red (660 nm) rays are particularly effective — prevents flowering. (C) unless
# it is followed by irradiation with far red (730 nm) light (D).

Pictures help:

So basically if you can hit your plants with infrared light at sundown for a short period of time you can reduce the amount of light needed. I happen to be at Lat 36 and my peak amount of daylight is 14, so by exposure of 730nm, I have now 'tricked' the plant into thinking there is 12 hours of darkness, hence inducing flowering at any time of the year.

Here are the links of where I obtained the information. They have more detailed info and are a good read. Some of it is confusing, still... but the main points for ourselves is in there.

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Photoperiodism.html
http://en.wikipedia.org/wiki/Photoperiod
http://en.wikipedia.org/wiki/Phytochrome
http://www.mobot.org/jwcross/duckweed/phytochrome.htm

If anyone else has information or real experience to bring to the table, that would be wonderful. Any comments and civil criticisms are welcome as well.

Thanks

Guest · Apr 10, 2008

Hey Mr. celcius

Thats interesting and something i may want to look at. Do you have any thoughts on how I can shine the UV rays on an outdoor plant? Is there some kind of light like that?

We could get an idea if this would be effective quickly and easily in my view. I will just plant a clone from a strain that I know very well like sensi star or Maple leaf, one in which i had other specimens in other places to compare my finish date with and then start firing away at the target plant and see what happens.

This may hold promise Mr. C. Half of the good stuff i have learned have come from the same activity you are undertaking. Researching and reading about plants. Many of my ideas sometimes falter, but it only takes one good one to pay off. Keep pitchin them Mr. C. Find us a light source.

sb

little j · Apr 10, 2008

i have intended to start my thread of my grow and hopefully discuss the issues ive been having. the main one being i have the most screwed up seedlings ever. i started easter and we had some cloudy weather for a few days so i thought my seedlings (the ones that came up) were stretching due to that. but, some are not stretching. as a matter of fact i have 1 which is only about 1in tall with a couple sets of leaves. i have a couple that are 7in tall and only one set of leaves. they cant stand on their own. used a fan on them, no help. i have one a couple with deformities. major retards. slow to no growth. and last week 2 showed female. not normal for me this young. long hairs little bud looking thing on them. another showed hairs today.??? it has crossed my mind that it may have something to do with my new windows. we bought some that are mirrored and reflect some sun away. a special silver coating type of window. it may be doing things to my plant. i always start in my window sill and i know this year something is strange. sexing in 3 weeks. whats up with that??? this thread has made me consider this more.

knna · Apr 10, 2008

Interesting topic, Mr Celsius.

Ive hypothesized many times with this light manipulation, but i dont know anybody that has tried it. Some uncontroled experiments, not conclusive, thats all.

Ive researched this topic from long ago, and from my readings, i reached the conclusion that darkness requeriments for flowering may be shorted from 20 min to 2 h. Its a wide range, so we will need to perform experiments to check exactly how much we can shorten the dark requeriment. Half an hour would be too low to worth it IMHO, but 2h would be definitively an excelent improvement.

But to check it, first we need to caracterize accurately the dark need of our plants. As it depends on strain, we need to caracterize first the dark hours requeriments of a plant and then experiment with clones to check how much pythochrome's manipulation affect it. Lots of time and resources.

Im building an small PC cab in order to do this kynd of experiments, but anycase, needed experimenting will consume half year in best case.

Initially, ive thought to use filtered incandescent bulbs, wich are very good emiting far red. Maybe ill invest on a 730nm LED module.

Time ago i saw a laser diode module designed to be used at greenhouses. It was iluminating all the greenhouse secuentally (plant per plant, arrow per arrow), either with 660nm light (to keep flowering long day plants) or 725nm light (to keep flowering short day plants). Ive never heard of it again, so it wasnt very sucesfull, thought.

In the light analysis sheet ive linked some times, you can calculate the pytochrome photostationary equilibrium using the full spectrum of phytochrome's absortion, not only the narrow red and far red bands.

eace:
knna

Mr Celsius · Apr 10, 2008

Hi silverback, I'll be doing research with this if I can get ahold of a good LED array that puts out 730nm. Hopefully knna can point me in the right direction.

little_j, thats some interesting stuff going on... what spectrum's do your windows filter?

knna, I agree 30 minutes would not be worth it, but 2 would be great. Most strains I've dealt with, will flower with 13 hours of light and 11 hours of darkness; this make sense to me, because plants start to flower where I am at around the same photoperiod. I'm sure there would be some isolated strains that would respond differently, but we can probably generalize about our results.

Can you point me towards a good LED array that puts out only infrared? Could you also post the light analysis sheet?

Thanks :wave:

Guest · Apr 10, 2008

Not that it matters a great deal to the discussion but tomatoes are considered day neutral...

one of your links says so as well...

Still other plants, e.g. the tomato, are day neutral; that is, flowering is not regulated by photoperiod.

knna · Apr 10, 2008

I use most times 14/10 during the flowering peak and only once they revegetated, and i think it was due to a light leak.

I believe most strains dark requriments are between 9 and 10h, and closer to the low end. For sure there are northen strains with less than 9h of dark requeriment (for flowering).

Outdoors, there is a delay between reaching the dark requeriment and the flowering, the called preflowering transitional period. The time when stretch starts is the better point to check the natural photoperiod. If you wait for the flowering itself to start, it may be 3 weeks later.

If you want only one high power led or some medium power ones, the easier, although not the cheaper, site to buy it is roithner laser. Its a very especialized brand wich ships worldwide.

They have some leds or led modules emiting in the desired range. The best bang for the buck is the TO3A4-H720-180. Its 25,4€ (or 39,89 USD), and emits between 200 and 260 mW peaking at 720nm (about 10nm more at operating conditions and good cooling: the TO package is relatively easy to cool), with a consuption around 2,5W. There are other options emiting more concentrated beams (30º instead of 180º). The ceramic package C11A1-720-30 cost 5,17€ (8,12 USD) and emits between 28 and 35 mW for around 0,9W consumed. More pricey if you want same total output, but easy to cool.

Mr Celsius · Apr 10, 2008

Awesome, I'm also gonna check my local surplus electronics store... maybe they have it and its cheap.

I'm gonna try and see if I can get some to flower under 18-20 hours of light. I have Sour D, GDP and PK sitting in a cab vegging with my flowering autoflowers... kinda weird having both in there, heh

little j · Apr 10, 2008

all i know is the windows are to screen out uv rays. the sun really beats in this side of the house so we got these to tune down the heat. maybe it works maybe not. the house still gets plenty warm on this side.

mossy · Apr 11, 2008

Interesting info guys... :yes:

Guest · Apr 11, 2008

Hi knna, I too generally finish plants out under 14 with no revege. You are the first other grower ive heard make that statement. My outdoor plants start showing flowers just under 14 hrs around the first of August. In my view, its innacurrate to believe that outdoor daylength must reach 12/12 before flowering sets in. I know strain selection has a big impact most of what I have grown did not need 12 hrs of darkness to begin flower.Just me thinking though and probably too much again.

Mr C. is it your understanding that this type of light infusion only effects flowering and not sexual orientation? Any chance of forcing male flowers along with speeding up flowering?
sb

Mr Celsius · Apr 11, 2008

If you mean it would cause hermaphrodites, it think its highly unlikely. Phytochrome is mostly responsible for the induction of flowering, not the gender selection. It also causes the "stretch" signaling to the plant what Pfr hits it; The infrared goes through whatever is shading the plant and that tells the plant that its being shaded, so it should stretch for light.

I'm doubting it would speed up flowering, as once a plant is in flowering, many other photoreceptors are responsible for the growth. Phytochrome mostly just initiates flowering.

simple gardener · Apr 11, 2008

Interesting, I've read about this the experts say that an hour of red light at the end of the light cycle helps to ''put the plant to sleep", which in effect changes the photoperiod, hence flowering time. It can actually be seen as a physical response: the leaves droop as though the plant is under-watered, but it isn't. Presumably it's a signal to the plant that it's in an exposed location and there are possibly cold nights ahead. Anyone seen or heard this?

Mr Celsius · Apr 11, 2008

simple gardener said:
Interesting, I've read about this the experts say that an hour of red light at the end of the light cycle helps to ''put the plant to sleep", which in effect changes the photoperiod, hence flowering time. It can actually be seen as a physical response: the leaves droop as though the plant is under-watered, but it isn't. Presumably it's a signal to the plant that it's in an exposed location and there are possibly cold nights ahead. Anyone seen or heard this?

Correct me if I'm wrong, but I believe is the turgor of the plant relaxing because it is no longer photosynthesizing. Mind you there glucose and hormones are still flowing through the xylem and phylum, I just believe there is less pressure on the overall tissue. Also, I believe the stomata are closing to reduce transpiration and retain heat for the night.

knna will probably be able to correct me on this.

simple gardener · Apr 14, 2008

The post I'm thinking of was deleted so I might be wrong about that, just thought I'd mention it because I'm almost sure they said it was not low turgor, but a sleep movement. Maybe someone else knows about it? If not just forget what I said.

Mr Celsius · Apr 14, 2008

Well plants can move in three ways (that I know of)
1) Cellular growth
2) "Acid Growth" (like venus fly traps)
3) Transfer of fluids (turgor)

Update:

Unfortunately I have not been able to find 730nm LED's locally... so I will probably have to purchase them online. Does anyone know how to possibly filter an incandescent to only show 730nm (knna?)?

I'm really trying to get this going, as to maybe help any of the outdoor growers this season.

kaljukajakas · Oct 19, 2008

You can buy an near infrared photography filter like this:

http://www.amazon.com/Hoya-58mm-RM-...2?ie=UTF8&s=electronics&qid=1224399502&sr=8-2

So you just have put this in front of a normal incandescent light and make sure all the light that hits the plants goes through the filter first. You should be able to flower your plants in 10-8 hours of darkness.

kaljukajakas · Oct 19, 2008

Here's a comparison I made of phytochrome R and RF absorbtion spectra with the transmission spectrum of a Hoya R72 filter:

Not perfect but good enough: the filter will let through a little bit of light below 730nm but a whole lot more over it. The FR:R ratio is what matters.

Theoretically you could buy this filter for 40$ and put it in front of a cheap halogen bulb with a built-in reflector in a light-tight frame and then start flowering with 14-15 hours of light a day... Sounds a bit too good to be true

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Phytochrome and forced flower via spectrum alteration

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