Sugar demand, not auxin, is the initial regulator of apical dominance

[cannacultural]

I just came across this new research paper that was just published. Might be of interest you yall. Here is the abstract.



Sugar demand, not auxin, is the initial regulator of apical dominance

Michael G. Masona, John J. Rossb, Benjamin A. Babstc, Brittany N. Wienclawc, and Christine A. Beveridgea,

School of Biological Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia; School of Plant Science, University of Tasmania, Sandy Bay, TAS 7005, Australia; and Biosciences Department, Brookhaven National Laboratory, Upton, NY 11973-5000

Edited by Deborah P. Delmer, University of California, Davis, CA, and approved March 14, 2014 (received for review November 25, 2013)

For almost a century the plant hormone auxin has been central to theories on apical dominance, whereby the growing shoot tip suppresses the growth of the axillary buds below. According to the classic model, the auxin indole-3-acetic acid is produced in the shoot tip and transported down the stem, where it inhibits bud growth. We report here that the initiation of bud growth after shoot tip loss cannot be dependent on apical auxin supply because we observe bud release up to 24 h before changes in auxin content in the adjacent stem. After the loss of the shoot tip, sugars are rapidly redistributed over large distances and accumulate in axillary buds within a timeframe that correlates with bud release. Moreover, artificially increasing sucrose levels in plants represses the expression of BRANCHED1 (BRC1), the key transcriptional reg- ulator responsible for maintaining bud dormancy, and results in rapid bud release. An enhancement in sugar supply is both neces- sary and sufficient for suppressed buds to be released from apical dominance. Our data support a theory of apical dominance whereby the shoot tip’s strong demand for sugars inhibits axillary bud outgrowth by limiting the amount of sugar translocated to those buds.

 

[Only Ornamental]

Thanks for sharing!

 

[Tonygreen]

Ill try feeding my girls sugar water when im topping and see what happens. I have some very stubborn sour bubbles I love that Ive grown enough that it will be easy to see any difference.

 

[Only Ornamental]

Tony, you should feed sugar to non-topped plants; theoretically they might branch. There's only a point in doing so with topped ones if they're not branching despite topping.

 

[Terps]

Wouldnt molasses do the same thing as sugar water?

 

[Only Ornamental]

AFAIK, molasses contains mainly sucrose and raffinose... on the other hand, the sugar mentioned in above publication is glucose. The plant should break the di-/trisaccharides down to liberate bound glucose. But this well regulated process may hamper an effect on bud growth. Remains to be proven .

 

[Anders89]

There is someone here on icmag who tested a side by side with clones where one side was fed with molasses and one not. It gave one ounce extra per plant.

 

[staank]

Interesting stuff. I think there was an organic thread where someone was doing glucose foliar spray but no reason was given other than plants use glucose.

 

[Tonygreen]

Tony, you should feed sugar to non-topped plants; theoretically they might branch. There's only a point in doing so with topped ones if they're not branching despite topping.

I will run the topped ones next to some untopped with the sugar. If you dont top this cut it simply wont branch so it will be easy to spot. I need the normal way I top them as a control of sort.

 

[Medicgray]

Sweet....literally

 

[cannacultural]

If you're interested in the full paper here is a link <http://www.filedropper.com/pnas-2014-mason-1322045111>

Will be interesting to see how this applies to Cannabis and how it might best be applied.

 

[bluhazy]

thx for the heads up, interesting reading

 

[dr.420]

black strap and huge buds.

black strap and huge buds.

black strap molasses is about the best sweetner on the market for sweetening buds, or so i have heard. upon hearing that i did a bit of study on the subject of sweetners. molasses has more sucrose, and sacrine sweetners than it does glucose, but it does have glucose in it, but it not about just any one sweetner its the presence of all three that are in the molasses that the plants love. the glucose produces, or reprroduces itself as a hardening agent think surgar crystals that sets the firmness of the buds and aids in the production of the trichomes, but it the high levels of the sacrose sacrine that produces the sticky sappy resins that are found in the sweet sticky buds. unlike sugar water foliar sprays that leaves a hard film on the buds and leaves these sweetners found in molasses are feed only at the last week or two with only water giving the buds an almost steroidal like boost. creating a doubling of the top nodal buds, and a tripiling of the lower buds. and thats fromm only two weeks usage in flowering. now throw it for a week after each two week or two week depending on how you fflush in flower and how often. regular flushing and sweetning in flower produces the juciest sweetest smelling and tastiest buds u could imagine and the smoke is the most pleasant u ll ever have. or so im told.

 

[cannacultural]

I've finally had time to read this over more carefully. Some interesting details in the study - that depending which nodes (lower or higher) effect the delay/amount of growth post decapitation. They also discuss how the sucrose is applied - directly to the buds. So while using molasses might have some benefit as discussed here, it may not fully work in regard to bud initiation. It would be interesting to do a side by side of a control, a molasses feed plant and a plant with a sucrose solution applied to the stem/bud tissue (foiliar spray or injection?).

The study also discusses the use of cytokinins to increase lateral branching, aside from products (I'm thinking seaweed based) which include them as a root application, is there documentation of people trying that as a localised application? (probably some fancy product for this out there I'd guess?)

Going back to molasses, is anyone aware of research regarding it's uptake by roots? I've read plenty on it (from various non scientific journal sources) and it all sounds great, and I have been trailing it. But I am still a bit skeptical on the plants ability to take up the sugar component - as I see it, the molasses supplies base nutrients and feeds the rhizosphere more than contributing directly to the plant (please correct me!)

 

[lost in a sea]

plant roots do have transporter proteins for carbohydrates. Different plant species have different tastes for which they want and at what times. ie tomatoes prefer sucrose to glucose and melons prefer fructose to either of those.

generally speaking the last weeks are when cannabis can get the most out being supplemented with more carbs. but that depends on the plant and which carbs they are getting in the molasses which is a dark area because the percentage will vary quite between sources and even batches from the same company.

which saccharides they want more of changes throughout their lifecycle, the rest will probably be consumed by beneficial bacteria or the plant later.

Personally i only use molasses as part of a microbe tea.. According to the tests done on supplementing carbs less than 10% is used and the rest is wasted.

 

[KushTrees]

Thanks for sharing this with us, CC. Very interesting.

 

[GrowerGoneWild]

Interesting.. so in theory, I could foliar feed sucrose to a topped plant to increase its response to branch more aggressively.?

In theory, could this be applied to those of us growing SCROG?

I see sucrose is the carbohydrate used for the study.. is sucrose ideal for cannabis?
Any thoughts on other sugars?.. glucose/fructose etc..

I'll have to read the study..

 

[Tonygreen]

To trace the sugars, the scientists first had to add a radioactive “tag” to these molecules. The tag they used was a positron-emitting isotope of carbon, carbon-11, incorporated into carbon dioxide. When they administered this labeled CO2 to plant leaves, the plants incorporated the radioactive carbon into sugars via photosynthesis. The scientists then tracked the labeled sugars throughout the plant using detectors placed along the plant stem.


“Ben's work was critical for this study,” said Christine Beveridge of the University of Queensland, Australia, who was the lead author on the paper. “His finding that sugars move at 150 cm per hour along the stem is amazing. The technique available in his lab is truly first class and an invaluable resource for plant scientists worldwide.


“We found that upon decapitation of the plant, there is a rapid increase in sugar delivery to the buds, which promotes bud outgrowth,” Benjamin Babst said. The sugars move about 100 times faster than auxin, a plant hormone previously believed to regulate bud growth. This finding supports the idea that sugar—not auxin—is the key signaling molecule for this immediate response to clipping.

“Auxin plays a secondary role later in the process,” Babst said.

quoted from http://www.newswise.com/articles/tracking-sugar-movement-in-plants

 

[Tonygreen]

Does anyone know how well plants repsond to injection via syringe? Perhaps a small sucrose injection into the petiole would work, never shot up a plant before heh. Seems better than slicing it a little?

 

[Tonygreen]

Well I found this...

http://onlinelibrary.wiley.com/doi/10.1046/j.1439-037x.1999.00331.x/abstract

Interesting note "Corn plants injected with salicylic acid (SA) produced 9 % more grain yield than plants injected with no PGRs. "