RastaLee
Member
(If you want to cut to the chase….read my hypothesis below which is BOLD and in BLUE…otherwise, feel free to read through from the beginning. All constructive criticism and scientifically relevant comments are welcomed. )
Hey everyone, so I’ve seen numerous posts with multiple experiments in regards to defoliation. However, while topping a few of my ladies the other day, I started to think about the whole defoliation debate differntly. One of the newest experiments performed was done by ProfTerpen. His experimental model was exceptionally well thought out and executed in my opinion. (His experiment had a very good control specimen, a very good experimental specimen, and went above and beyond to eliminate confounding variables)
When ever people talk about defoliation, it seems that those that are IN FAVORof defoliation hypothesize that removing clusters of fan leaves exposes more bud sites to direct light and should THEORETICALLY increase yield. Those that ARE OPPOSED to defoliation, hypothesize that removing clusters of fan leaves reduces the overall photosynthetic capabilities of the plant as a whole and negatively impacts yield.
Although one would think that the exposure of buds to direct, unshaded light should undoubtedly increase the photosynthetic capabilities of the particular bud site in question…I have not seen any experiments in regards to the role of plant growth hormones/factors and their distribution through the vascular tissues when defoliating. Since plants are vascular, their method of redistributing nutrients are very similar to humans. Not only do they have “veins and arteries” in the form of xylem and phloem, but they also perform active transport, passive transport, and direct cell to cell redistribution. The easiest example I could think of is cardiac muscle (heart muscle) which utilizes INTERCALATED DISCS to quickly and efficiently transport ions with electrical activity DIRECTLY from one cell to another without the use of vascular structures.
MY HYPOTHESIS: Most of us know that auxin / cytokinin production (and more importantly…their distribution) governs the growth of a plant. If you don’t know about auxins and other plant hormones, you should read up on these first. Bellow are the most basic forms of plant hormones:
The highest concentration of auxins are found at the top (apical portion) of a plant. The highest concentrations of Cytokinins are found in the roots.This is why when you cut the top off of a plant, the lower shoots take over and fight for dominance. It is the changes of the concentrations of hormones relative to one another that trigger metabolic changes. A simple example would be 10 units of growth hormone travelling down a stem. 10 units would have to split evenly into two equal 5 units if that stem were to branch into two separate stems at an inter node. Example: 10 units enter the stem here ----------< at the split each branch gets 5 units of hormone.
As mentioned above, there is an no argument that there is an increase in direct light exposure to buds with defoliation. And there is also no argument that removing perfectly healthy leaves decreases the overall photosynthetic available surface area of a plant as a whole. However, my theory as to why some people claim increased yield with defoliation has MORE TO DO WITH THE REDISTRIBUTION OF HORMONES AND CHANGES TO THE RELATIVE CONCENTRATIONS THROUGH THE PLANTS TISSUES. As mentioned above....plants are highly vascular organisms that constantly redistribute nutrients and growth factors in the same way that humans moves nutrients, hormones, and growth factors through arteries and veins. Another practical example…when someone does bicep curls with a heavy weight….the muscles use glycogen stored directly in them to perform work….after these glycogen stores become depleted, the arteries that feed the bicep will dilate in order to increase the blood supply to the active bicep so that it can continue to perform work. More importantly, even hours after you stop doing bicep curls, the vessels remain dilated to restore the glycogen stores and prepare the muscle for the next time it will be "stressed".
I hypothesize that in the same manner, if you remove many leaves off a particular branch, the plant senses this change and adapts by redistributing more nutrients and growth factors to the newly defoliated branch. One thing that is known and mentioned in the Wikipedia article, is that defoliation decreases the levels of auxins on a particular branch and “delays the senescence of flowers”….which means the flower portion of the plant maintains is biological and metabolic processes for a longer period of time in comparision to untouched branches with flowers. It is in my opinion that the combination of increased light and altered distribution of these hormones and growth factors is what actually provides and increased yield. Plants can “see” light and generally grow towards light. However, they can also see shade (ie the relative competition in a given growing area) by utilizing the far red spectrum which passes THROUGH leaves. You should read more about the effects of the far red spectrum and the relationship to plants that are being shaded out by other plants. At watered down version can be found here: https://en.wikipedia.org/wiki/Shade_tolerance .
For the record…I didn’t just use Wikipedia….ive been reading though a few plant physiology books my local library gave away a few months back to make space for newer books. I used Wikipedia as a source because everyone has access to it and it is generally easier to read. I have a degree in biology and have done quite a bit of research in the botany field....but I am in no way an expert on cannabis. While I'll admit ive only been growing for about a year....most of my progress has been made through reviewing botany and plant physiology books...and of course RIU.
In the experiment I am performing…. I took a single (Cali Connection) Sour Diesel Plant grown from seed and completely defoliated ONE SINGLE BRANCH in its entirety… 3 weeks into flower after a 60 day vegetation cycle. The branch chosen shares a common node with an identical branch and is a “Y” shape. The left side of the “Y” was completely defoliated and the right side of the “Y” was left alone. The size and structure of both sides of the "Y" were virtually identical. Being that no clones need to be cut, it elminates the confounding variables when it comes to cloning technique. I chose to do it at 3 weeks because the recommended flower time is 8-10 weeks and from my experience with this strain in the past, the majority of bud swelling and growth occur after the second week into flower when the entire plant has had adequate time to realize the days are shorter and all flowering hormones have had a chance to adequately increase. As stated before, I’d appreciate constructive criticism in the experimental design. I chose to use one plant because almost everyone has done multiple plants/clones. I anticipate sources of error to be:
Hey everyone, so I’ve seen numerous posts with multiple experiments in regards to defoliation. However, while topping a few of my ladies the other day, I started to think about the whole defoliation debate differntly. One of the newest experiments performed was done by ProfTerpen. His experimental model was exceptionally well thought out and executed in my opinion. (His experiment had a very good control specimen, a very good experimental specimen, and went above and beyond to eliminate confounding variables)
When ever people talk about defoliation, it seems that those that are IN FAVORof defoliation hypothesize that removing clusters of fan leaves exposes more bud sites to direct light and should THEORETICALLY increase yield. Those that ARE OPPOSED to defoliation, hypothesize that removing clusters of fan leaves reduces the overall photosynthetic capabilities of the plant as a whole and negatively impacts yield.
Although one would think that the exposure of buds to direct, unshaded light should undoubtedly increase the photosynthetic capabilities of the particular bud site in question…I have not seen any experiments in regards to the role of plant growth hormones/factors and their distribution through the vascular tissues when defoliating. Since plants are vascular, their method of redistributing nutrients are very similar to humans. Not only do they have “veins and arteries” in the form of xylem and phloem, but they also perform active transport, passive transport, and direct cell to cell redistribution. The easiest example I could think of is cardiac muscle (heart muscle) which utilizes INTERCALATED DISCS to quickly and efficiently transport ions with electrical activity DIRECTLY from one cell to another without the use of vascular structures.
MY HYPOTHESIS: Most of us know that auxin / cytokinin production (and more importantly…their distribution) governs the growth of a plant. If you don’t know about auxins and other plant hormones, you should read up on these first. Bellow are the most basic forms of plant hormones:
The highest concentration of auxins are found at the top (apical portion) of a plant. The highest concentrations of Cytokinins are found in the roots.This is why when you cut the top off of a plant, the lower shoots take over and fight for dominance. It is the changes of the concentrations of hormones relative to one another that trigger metabolic changes. A simple example would be 10 units of growth hormone travelling down a stem. 10 units would have to split evenly into two equal 5 units if that stem were to branch into two separate stems at an inter node. Example: 10 units enter the stem here ----------< at the split each branch gets 5 units of hormone.
As mentioned above, there is an no argument that there is an increase in direct light exposure to buds with defoliation. And there is also no argument that removing perfectly healthy leaves decreases the overall photosynthetic available surface area of a plant as a whole. However, my theory as to why some people claim increased yield with defoliation has MORE TO DO WITH THE REDISTRIBUTION OF HORMONES AND CHANGES TO THE RELATIVE CONCENTRATIONS THROUGH THE PLANTS TISSUES. As mentioned above....plants are highly vascular organisms that constantly redistribute nutrients and growth factors in the same way that humans moves nutrients, hormones, and growth factors through arteries and veins. Another practical example…when someone does bicep curls with a heavy weight….the muscles use glycogen stored directly in them to perform work….after these glycogen stores become depleted, the arteries that feed the bicep will dilate in order to increase the blood supply to the active bicep so that it can continue to perform work. More importantly, even hours after you stop doing bicep curls, the vessels remain dilated to restore the glycogen stores and prepare the muscle for the next time it will be "stressed".
I hypothesize that in the same manner, if you remove many leaves off a particular branch, the plant senses this change and adapts by redistributing more nutrients and growth factors to the newly defoliated branch. One thing that is known and mentioned in the Wikipedia article, is that defoliation decreases the levels of auxins on a particular branch and “delays the senescence of flowers”….which means the flower portion of the plant maintains is biological and metabolic processes for a longer period of time in comparision to untouched branches with flowers. It is in my opinion that the combination of increased light and altered distribution of these hormones and growth factors is what actually provides and increased yield. Plants can “see” light and generally grow towards light. However, they can also see shade (ie the relative competition in a given growing area) by utilizing the far red spectrum which passes THROUGH leaves. You should read more about the effects of the far red spectrum and the relationship to plants that are being shaded out by other plants. At watered down version can be found here: https://en.wikipedia.org/wiki/Shade_tolerance .
For the record…I didn’t just use Wikipedia….ive been reading though a few plant physiology books my local library gave away a few months back to make space for newer books. I used Wikipedia as a source because everyone has access to it and it is generally easier to read. I have a degree in biology and have done quite a bit of research in the botany field....but I am in no way an expert on cannabis. While I'll admit ive only been growing for about a year....most of my progress has been made through reviewing botany and plant physiology books...and of course RIU.
In the experiment I am performing…. I took a single (Cali Connection) Sour Diesel Plant grown from seed and completely defoliated ONE SINGLE BRANCH in its entirety… 3 weeks into flower after a 60 day vegetation cycle. The branch chosen shares a common node with an identical branch and is a “Y” shape. The left side of the “Y” was completely defoliated and the right side of the “Y” was left alone. The size and structure of both sides of the "Y" were virtually identical. Being that no clones need to be cut, it elminates the confounding variables when it comes to cloning technique. I chose to do it at 3 weeks because the recommended flower time is 8-10 weeks and from my experience with this strain in the past, the majority of bud swelling and growth occur after the second week into flower when the entire plant has had adequate time to realize the days are shorter and all flowering hormones have had a chance to adequately increase. As stated before, I’d appreciate constructive criticism in the experimental design. I chose to use one plant because almost everyone has done multiple plants/clones. I anticipate sources of error to be:
- The timing of the defoliation (vegetative stage vs 1st week of flower vs 2nd week vs 3rd week…etc)
- Nutrients/medium/light source used (I will list these later after I take pictures and get them up, but since both branches are still attached to the same plant, with similar bud sites and branch diameter, with a shared medium, with the same vascular system, etc )
- Area of plant defoliated ( I plan to repeat the experiment again defoliating all the branches on one half of a single plant)
