Purple Striped Stems...

[B Sparkles]

Purple striped stems...its an expression of strains that have a tendency to purple out in late flower with cooler temps (but its not a guarantee it will be purple, ironically all my true purple strains are completely green in veg). Striping shows in veg if your night temps dip into the 60s and your water pH sits between 6.0-6.4, below 6.0 it starts to fade and above 6.4 the plants don't like it and stems get woody. Higher temps at night and the stems will stay green and the plant bushes a little more. I don't think its a bad thing at all, just the plants reaction to slightly cooler temps in the proper pH range.

 

[Erkbud]

I started this plant 4 weeks ago. I found the seed in some rec store weed (hybrid) so not sure of origin. Certainly indica dominant. First 3 weeks under full spec LED now 1000w mh for a week. Grown in FF ocean w/ no added nutes. Only about 12" tall. In 10 gl smartpot.

 

[Rb2242]

I use Black Dog LED and they have a post about the pink/purple stems in their FAQ’s specifically relating to high end LED lights which produce UV (unlike Most low end LED and most other grow lights which do not produce UV).
It is NOT a deficiency or problem, simple the plant responding to the UV light with its full color spectrum showing. A deficiency will almost always be accompanied by other signs of stress and discoloration of the leaves. If you only see the pink/purple stalks, AND are using high end LED, AND there is no other leaf discoloration, leave it alone - you’re babies are just getting supercharged and will grow massively. See below for the full Q + A directly from Black Dog LED...
....
.....
Do LED lights cause magnesium deficiency in plants?
Is it normal to see purple streaks on the stems / petioles?

No, LED lights do not cause any kind of nutrient deficiency; purple streaks on stems and petioles are a normal response to exposure to ultraviolet (UV) light.

A rumor was started that LED lights cause magnesium deficiency when people noticed that some plants develop purple petioles (leaf stalks) or streaks on the stems under LED lights, but not under HPS lights. While purple coloration on stems and petioles can be one of the signs of magnesium deficiency in plants, it is also a sign that the plant is producing natural purple pigments (anthocyanin) in response to ultraviolet (UV) light. Many artificial lights (including HPS and most LEDs) don't give off UV light, so plants grown under these lights don't produce this natural pigmentation. Under these UV-lacking lights, purple coloration is often a sign of magnesium deficiency. However, when grown under UV-containing Black Dog LED lights or natural sunlight, plants will produce their full range of natural pigmentation-- it is not necessarily a sign of a nutrient deficiency.

The major symptom of magnesium deficiency is usually yellowing, blotchy-looking (chlorotic) leaves, accompanied by purple stems and petioles. When growing under Black Dog LED grow lights, unless the leaves are chlorotic, purple stems and petioles are not a sign of a magnesium deficiency-- they are a sign of a happy, healthy plant.

 

[NugNutz]

Ok I thought I'd start doing some digging on this subject. I've only just started so, I can't say I have any definitive answers; however I DO believe we can narrow / specify things a bit.

With plants there are only a few sets of pigments (biochromes) that are even possible. So, first; the coloration we see must be one of these pigments.
The pigments in plants are: Chlorophyll, Carotenoids, Anthocyanins and Betalains. You can find this info here: reference

We can look at these and further reduce this down. Chlorophyll is responsible for green and we are all aware of it. Carotenoids are responsible for red, orange or yellow colorations and would be most common in carrots. Anthocyanins cover the largest category of colors including red, blue, purple, yellow-green and even colorless. Betalains are red or yellow also but cannot occur in situations where Anthocyanins do. Now, Anthyocyanins are somewhat unique in that they do occur in virually all live parts; including roots, stems, leaves, flowers; etc.

From this; we can easily presume that the pigment responsible for colors in cannabis (this would be inclusive of reds, purples or blacks in stems, leaves and flowers) is Anthocyanins. You can find some basic info on this pigment here; reference.

Some things of particular note here are that "Anthocyanins can be used as pH indicators because their color changes with pH; they are pink in acidic solutions (pH < 7), purple in neutral solutions (pH ~ 7), greenish-yellow in alkaline solutions (pH > 7), and colourless in very alkaline solutions, where the pigment is completely reduced".. Also, that "Anthocyanins are found in the cell vacuole, mostly in flowers and fruits but also in leaves, stems, and roots. In these parts, they are found predominantly in outer cell layers such as the epidermis and peripheral mesophyll cells"

Also, I suppose the explanation for autumn leaves and strains that tend to "naturally" turn purple towards harvest; may also be of similar origin or nature.
"The reds, the purples, and their blended combinations that decorate autumn foliage come from anthocyanins. Unlike the carotenoids, these pigments are not present in the leaf throughout the growing season, but are actively produced towards the end of summer.[27] They develop in late summer in the sap of the cells of the leaf, and this development is the result of complex interactions of many influences, both inside and outside the plant. Their formation depends on the breakdown of sugars in the presence of bright light as the level of phosphate in the leaf is reduced."

There are a few other resources that I'm currently looking through; but it seems we can explain many of these color expressions.

reference
"Plants also show tremendous diversity in anthocyanin expression. In leaves, for example, anthocyanins may colour the entire blade, or else be restriced to the margins, stripes, patches, or seemingly random spots on the upper, lower or both lamina surfaces. In some leaves, only the petiole and major veins are pigmented red, in others it is the interveinal lamina tissue, or the stipules, or domatia that are anthocyanic. .........."In many species, anthocyanins are produced only when the plant is unhealthy or has been exposed to environmental stress, but there are some that develop the red pigments even under optimal growth environments."

"Irrespective of their cellular location, however, anthocyanin biosynthesis in many leaves is generally upregulated in response to one or more environmental stressors. These include: strong light, UV-B radiation, temperature extremes, drought, ozone, nitrogen and phosphorus deficiencies, bacterial and fungal infections, wounding, herbivory, herbicides and various pollutants. Because of their association with such biotic and abiotic stressors, anthocyanins are usually considered to be a stress symptom and / or part of a mechanism to mitigate the effects of stress."

If we look at merely this section here; it would cover all the possible aspects about purple striped stems that have been proposed (xD), even though fairly open and no reasoning. Though, it is possible to have a anthocyanic response from temp, season, N-, P-, Light, etc etc; including that it can be a normal expression. In fact, since many ornamental flowers do this "normally" there has been much investigation into this; so that's good from a certain perspective.

My intent now, I suppose, is to try and see if there's much research as to what is going on inside the plant to cause these changes. Possibly we can get to some evidence and maybe even tests with "candy stripes" specifically. My first thoughts are (since the color of pigment is altered by pH) that something is causing an internal change to the pH where these pigments are located that is leading to the stripes we see. I'm guessing that there's some by-product created from moving various organic / inorganic compounds internally that possibly get deposited or accumulated which causes the pH change. I'm not sure if I'll easily find the answer as I cannot think of another type of plant species that does show this particular characteristic.

This book: resource From what I was able to read; covered the various ways that coloration of anthocyanins can occur. A couple notes of interest from this;
"Anthocyanins are stored in an organized aqueous medium in the cell vacuoles. A slightly acidic environment (pH 3-5) rich in inorganic ions and other polyphenols is essential for the transformations in these pigments that enable the formation of molecular complexes and subsequent color changes and stabilization."

another quote I will shorten to make it a tiny bit more digestable;
"The structure depicted in Fig. 1.2 depicts the positively charged flavylium cation, which is the dominant equilibrium form in strongly acidic solutions. The positive charge is delocalized throughout....although carbons 2 and 4 are the more positively charged atoms. The relative ease of deprotonation of the two OH at positions 4 and 7 contributes to the color changes of anthocyanin. One of these OH loses a proton at pH~4 producing bases that exhibit a chromatic deviation toward longer wavelengths. At pH close to neutrality, a second deprotonation occurs leading to the formation of the anionic bases, with another blue shift in the absorption spectrum."


Possibly has one avenue of interest for our situation here; Metalloanthocyanins.
"All anthocyanins possesing a catechol structure in their B-ring, that is, all derivatives of cyanidin, delphinidin, and petunidin, are known to have the capacity of complex formation with several small divalent and trivalent metal cations. This type of association has been demonstrated to be at the origin of the blue color in some flowers. Metals most commonly found in the formation of such metalloanthocyanins are Iron (III), Magnesium (II) and Aluminum (III)."

anyway. At least so far we can say what it is that's being expressed. I'm not sure if there will be a way to nail things down further, but I'll keep digging some. If I find any more goodies; I can post them if anyone wants.

hope this helps

Wow man..just...wow. I went into a blanked out reverie while reading all that and just let the info in.. this is an old thread but I'm currently growing 5 different strains and all but 1 out of the ten mothers have almost deep radish red stems one really red but growing fine, some others were starting to go red from the top down.. It was time to top dress so deficiency a bit, the room had temp swings from 28 29 c lights on to 16 17 lights off, I was using cheap leds and I was trying to ph closer to 6.8 with drops and probably was closer to 7.0 . I believe all these factors came to play to make it red and I think that kind of goes along with what you were researching. I've changed my ph and top dressed. I'll see what happens.. thanks forthe info!

 

[London bud]

Purple stripes on the stem are usually a sign of stress. I normally observe this happening after supercropping or topping and sometimes its pH related.
Once the plant has recovered from the stress of being topped, supercropped, trimmed, bent, broken or whatever or after pH issues have been resolved you should notice new growth on the stem come through green and stay green.
Maybe sometimes stripes on the stalk are genetic but from my own experiences I've only ever seen this happen as a result of stress. Its not a good thing from what I've personally seen.

 

[NugNutz]

Purple stripes on the stem are usually a sign of stress. I normally observe this happening after supercropping or topping and sometimes its pH related.
Once the plant has recovered from the stress of being topped, supercropped, trimmed, bent, broken or whatever or after pH issues have been resolved you should notice new growth on the stem come through green and stay green.
Maybe sometimes stripes on the stalk are genetic but from my own experiences I've only ever seen this happen as a result of stress. Its not a good thing from what I've personally seen.

Yea, I see the new green growth already after proper ph, food and rest.

 

[umop apisdn]

I use Black Dog LED and they have a post about the pink/purple stems in their FAQ’s specifically relating to high end LED lights which produce UV (unlike Most low end LED and most other grow lights which do not produce UV).
It is NOT a deficiency or problem, simple the plant responding to the UV light with its full color spectrum showing. A deficiency will almost always be accompanied by other signs of stress and discoloration of the leaves. If you only see the pink/purple stalks, AND are using high end LED, AND there is no other leaf discoloration, leave it alone - you’re babies are just getting supercharged and will grow massively. See below for the full Q + A directly from Black Dog LED...
....
.....
Do LED lights cause magnesium deficiency in plants?
Is it normal to see purple streaks on the stems / petioles?

No, LED lights do not cause any kind of nutrient deficiency; purple streaks on stems and petioles are a normal response to exposure to ultraviolet (UV) light.

A rumor was started that LED lights cause magnesium deficiency when people noticed that some plants develop purple petioles (leaf stalks) or streaks on the stems under LED lights, but not under HPS lights. While purple coloration on stems and petioles can be one of the signs of magnesium deficiency in plants, it is also a sign that the plant is producing natural purple pigments (anthocyanin) in response to ultraviolet (UV) light. Many artificial lights (including HPS and most LEDs) don't give off UV light, so plants grown under these lights don't produce this natural pigmentation. Under these UV-lacking lights, purple coloration is often a sign of magnesium deficiency. However, when grown under UV-containing Black Dog LED lights or natural sunlight, plants will produce their full range of natural pigmentation-- it is not necessarily a sign of a nutrient deficiency.

The major symptom of magnesium deficiency is usually yellowing, blotchy-looking (chlorotic) leaves, accompanied by purple stems and petioles. When growing under Black Dog LED grow lights, unless the leaves are chlorotic, purple stems and petioles are not a sign of a magnesium deficiency-- they are a sign of a happy, healthy plant.

Interesting.. I heard about UVA/UVB/UVC possibly having a number of unanswered questions as far as which does what in regards to pigment and/or thc production even. I wonder if one form of UV might contribute more to color than others... Ironically, I just googled "uvb uvc growing" and this black dog article came up:

 

[umop apisdn]

Also... forgot to mention, I too have these "candy stripes" going on right now... but not sure if it's strain related / genes, or if it's due stress/nutrient related. They are 4 GSC "Thin Mints" plants, all have this going on...

Up until like yesterday, I assumed it was just the strain since I had heard/read somewhere GSC tends to do this, although if you look on b.jpg, there are some splotches that are very similar in color (look on lower part of b.jpg). Hence how I found this thread, also curious what's going on...

 

[umop apisdn]

and oooooh surprise!!! it's a girl i guess!! (see pic c haha)

 

[NugNutz]

Even with adjusting the temperature and feeding the Chemdog 91 sk va bx1 phenos shows it more and one pheno pure purple stems. I actually dont think I'll keep her as a mom, even without flowering. She seems to be affected and get hungry faster than the othe phenos.

 

[Jack og]

Phosphorus def? I keep some mothers a little deficient to load it prior to cuts.
Pheno striping is cool imo. But I haven’t seen it to be any top shelf winners honestly.

 

[skewbong]

IME, I see this a lot in bubblicious strain from Nirvana. There are a few different phenotypes, but my keeper plants, only bubblicious all had purple stripes. Always good yeild, and always healthy. I'm no expert, and will never claim to be. "The man who knows everything, learns nothing!" Definitely not my quote, but a favorite.

Been growing this strain for about 7 years, so I've gone a few rounds with this girl, lol. FYI, there are undesired phenos with this strain too. It has awesome jar appeal; if you cure with your sugar leaves on (only short ones) it looks silverish like sage, super frosty. Have a great day to all and stay safe

 

[Dave1923]

I've always had these "Stripers" never knew anything about it. They seem to be really healthy but has anyone ran into a problem with them. After the comment about the led lights, I would have thought they were due to that. I just don't know, will post picture of my current blue dream grow if you guys want to show off these Stripes. But should it be something i should be worried about, this is second crop since my high school days sooooo....