There is merit to phytochrome manipulation and I keep some 10 watt 740nm LEDs around just for this reason.
Phytochrome manipulationis well known in photobiology.
What is phytochrome manipulation?
Here's the gist of it: we both know that cannabis needs a 12/12 lighting cycle to intitate and maintain flowering/budding. But, cannabis plants will actually bud out in a 14/10 lighting cycle (14 hours of light with 10 hours of darkness each day) – the catch is that it takes longer for the plant to ripen so in the end you gain nothing.
Now onto phytochrome manipulation.
From wikipedia on phytochromes:
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 is found in the leaves of most plants.
Phytochromes can be manipulated with far red light to produce unique results that benefit the cannabis grower. By using far red light at the end of that 14/10 cycle, it forces a plant to "sleep" immediately so it doesn't take any longer to ripen.
The net result is about 17% greater yield.
The phytochrome protein group (there's 5 known so far, Phy A-E, the E version plays a different role than the other 4) plays a dominate role in the circadian rhythm of plants along with another vital protein, CONSTANS. Together they form a protein based clock. The clock is actually located in the leaves. When the light is at proper timing they release another protein, FLOWERING_LOCUS-T, which travels through the plant's phloem to shoot tips that then causes another protein to be expressed, FLOWERING_LOCUS-D. This initiates the flowering process in the shoot tip through a few other proteins (I forgot their names off the top of my head).
This is all known as the florigen hypothesis.
Long day and short day plants react just the opposite to phytochrome manipulation. Where as high red, low far red light stimulates flowering in long day plants, it's just the opposite in short day plants like cannabis.
I'm not sure anyone in the cannabis community realizes this, or why calling a red-only LED grow light a "bloom booster" is incorrect for short day plants.
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