BR vs. Broad Spectrum Effects on Sensory Quality

Blue Red or Broad Spectrum?

Sunlight, HPS, or LED?

Is Green a good light or a bad light? Which?


A recent study used the following light recipes, Greenhouse Sunlight, Blue, Red, Blue/Red, Blue/Red/Green, Blue/Red/Yellow, and Blue/Red/FarRed.

Yellow? BRY? Yep, and guess what? It was the stand out recipe.

Very interesting results.
LED lighting did a better job than the Sun.
BRY was the most surprising, affecting the most volatile compounds.
BRFr was similar to BRY.
BR vs. BRG was most interesting in that each combination affected about the same number of volatile compounds. But completely different compounds. This is where things get real interesting.

The researchers at the University of Florida have been very active in Genetically Modified Organisms to modulate biochemical responses. Those same researchers (Folta, Colquhoun) are now also using narrow band LED treatments to modulate biochemical responses.

Light spectrum can be used to change the sensory quality of fruits and vegetables, primarily by modulating the prevalence of specific volatile metabolites (Loughrin and Kasperbauer,2003). Light has been shown to affect volatile compounds in petunia flowers, in fruits (such as strawberry, blueberry, and tomato) and in tea leaves (Colquhoun et al.,2013; Fu et al.,2015).

This study was done with Basil. Basil and Cannabis have some things in common, aroma and oils.
Cannabis chemical constituents include about 120 compounds responsible for its characteristic aroma. These are mainly volatile terpenes (major components of resin) and sesquiterpenes.

Monoterpenes are a class of terpenes.

Phenylpropanoids are essential components of a number of structural polymers, provide protection from ultraviolet light, defend against herbivores and pathogens, and mediate plant-pollinator interactions as floral pigments and scent compounds..

Sesquiterpenoids compounds are essential to the plant’s healthy growth while under near constant mild microbial attack, and represent a large part of their defense to more serious damage. Sesquiterpene lactones is the bitterness they confer to foods such as chicory, where it is considered one of the main flavor aspects, but also in lettuce where it is considered detrimental to the taste.

Fatty aldehydeare are fragrance or flavoring substances commonly used in perfume.

Esters of Fatty Acids occur as colorless to brown powders, flakes, coarse powders, or granular or waxy lumps, or are a colorless to brown semi-fluids or liquids. They are odorless or have a characteristic odor.

Most fatty alcohols in nature are found as waxes which are esters with fatty acids and fatty alcohols Fatty alcohol is used as co-emulsifiers, emollients, and thickeners in cosmetics and food industry.

Esters of carboxylic acids tend to have pleasant odors and many are used in perfume.

Proponents of broad spectrum white LEDs have been dragging green in to the fray. Now we can drag yellow in also.

How will this study affect the argument over green, broad spectrum and narrow band? It won't. Each side will interpret how they see fit.

BR = Esters of carboxylic acids and Esters of Fatty Acids

BRG = Sesquiterpenoids and Phenylpropanoids

BRY and BRFr = Both

Narrow band proponents will pick BRFr and Broad Spectrum proponents will pick RBY.

One could make an argument for BR or BRG.

The tie breaker goes to BRY. BRY looks best in the picture. I like pictures.
And Green is the bad witch.




LINK TO STUDY FULL TEXT: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5007804/









https://en.wikipedia.org/wiki/Fatty_aldehyde
https://en.wikipedia.org/wiki/Fatty_acid_ester
https://en.wikipedia.org/wiki/Fatty_alcohol
https://en.wikipedia.org/wiki/Carboxylic_acid
https://en.wikipedia.org/wiki/Monoterpene
https://en.wikipedia.org/wiki/Phenylpropanoid

Is green the bad witch? Is yellow the good witch?

BGY may be the ideal seedling treatment.

I would say BGYFr but Far Red may negatively affect elongation. The effect of yellow in this experiment is not the only reason for my interest in yellow. Yellow and blue together do a better job of canceling the elongation cues of R:Fr ratio. The following is from the definitive textbook Plant Physiology and Development:

The biochemical circuits that connect light wavelengths to expression of specific genes and the metabolic networks they govern, are influenced far more by BRFr and BRY than BR alone to produce more terpenes and less carboxylic acid esters.

Cannabinoids are synthesized as carboxylic acids, Tetrahydrocannabinolic acid (THCA, derived from cannabigerolic acid [CBGA]), a precursor of THC, decarboxylated to THC with drying and especially under intense heating when smoked.

So if THCA is a carboxylic acid do we really want green wavelengths to divert photon energy to produce terpenes rather than carboxylic acid?

If THC is a terpenophenolic cannabinoid compound then do we want green? When?


If THCA is decarboxylated to THC when drying, then can light wavelengths modulate an improved decarboxylation process? Light treatment with narrow band LED light cues have been found to manipulate the quality of volatile compounds post harvest.


The University of Florida study "Light modulation of volatile compound from petunia flowers and select fruits" found blue, red and far red caused significant responses (5x) in tomatoes and strawberries that produced enzymes necessary for synthesis of volatile compounds affecting aroma and flavor.

NoFucks2Give said:

Yellow and blue together do a better job of canceling the elongation cues of R:Fr ratio

Click to expand...

Spectral yellow has a medium R:FR ratio. It's lower than red and the yellow is transmitted easier through the leaves than red. That should theoretically be enough for shade avoidance to work properly and have less need for FR. I think the yellows in warm white leds and HPS is what makes the spectrum very good for growing tall plants like weed.

Keep in mind that lettuce is a very different type of plant than plants that will compete to have a spot in the canopy.