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Plant Hormones
#1
This is a basic overview of a complicated subject where information is muddled by companies trying to sell you their bottle of magic potion or made almost indecipherable by scholar speak in research documents from universities. My hope is that others can find better resources than i did. It seems from what little i found on the subject, that the field of botany as a whole needs to allocate more resources to further the current understanding of plant hormones and how they interact with each other, the plant and the environment.

I have been interested in plant hormones for many years but i was only looking at Ethylene and Gibberellin like most cannabis folks do.

Over a year or so ago i became interested in the other hormones and how they all interact and flow within the plant.

As i started to understand the basics of the system i realized how this info shed light on a lot of strange behavior i have seen in cannabis through the years.

Understanding what‘s happening with hormones in plants is similar to understanding what’s happening with the hormones in humans with thyroid disease for example or teenagers as a more universal one.

 It’s another possible tool in the toolbox that helps us find them keepers.

The problem is the barriers mentioned at the top of the page, and this is where i could use some help from other people who see the worth in such information.

We can help each other discern whether or not we have a plant with the botanical equivalent of an endocrine disorder instead of doing what most other cannabis researchers have with this subject.

 
Plant Hormone Overview:

Brassinosteroids – [boss hormones, essentially a plants central nervous system] – A group of over 40(growing rapidly) chemical messengers that communicate with and control the Hormones listed below. This group controls all growth as well as the “immune system” a loose term describing defense mechanisms designed by plants over time. These hormones form and control a system of communication in plants.

 
Flower Growth Hormone Group: Hormones controling growth who exclusively communicate with each other via the Brassinosteroid System(BS).

Florigen – [the annual flower hormone] – Enables short day plants to measure darkness and tell the plant when to flower using the BS.

Auxin – [rooting hormone,mutation hormone] – Responsible for cell division in root tips and new growth tips. Controls apical dominance by regulating the ability of itself to be mobile within the plant using the BS.

Cytokinin – [growth hormone, plant HGH, mutation hormone] – In abundance and flowing freely this hormone makes every part of the plant larger throughout all stages of growth. It does not speed flowering as commonly believed, but it does make flowers larger. Also playing a role in cell division aside Auxin it comes with the risk of mistakes in the copying process and leading to possible mutations. This hormone is also responsible for female flowers appearing on male flowers in dioecious species and the male part of flowers(stamen) in monoecious species.

 
Flower Ripening Hormone Group: Hormones related to maturation who exclusively communicate with each other via the BS.

Ethylene – [female hormone, ripening hormone] – Responsible for female flowers, fast flowering and maturation of the plant through the BS.

Abscisin – [stress hormone, death hormone] – Stops cell division and closes stomata. This hormone triggers what is referred to as plant hibernation where the plant uses the BS to assess its situation and decide if it will attempt a recovery from the stress endured or give up and stay in hibernation and perish.

Gibberellin – [male hormone/plant testosterone] – Responsible for male flowers, rapid growth, long internodes and short life cycle by triggering
Abscisin through the BS. Male pollen used from high Gibberellin plants on females creates 99% feminine offspring in the resulting seed.

 
I really hope this outline is dwarfed by what others find and starts a thread that goes on for pages in the future and helps us all understand the plants we all love a little better.
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#2
(06-29-2019, 03:39 PM)Elka Wrote: This is a basic overview of a complicated subject where information is muddled by companies trying to sell you their bottle of magic potion or made almost indecipherable by scholar speak in research documents from universities. My hope is that others can find better resources than i did. It seems from what little i found on the subject, that the field of botany as a whole needs to allocate more resources to further the current understanding of plant hormones and how they interact with each other, the plant and the environment.

I have been interested in plant hormones for many years but i was only looking at Ethylene and Gibberellin like most cannabis folks do.

Over a year or so ago i became interested in the other hormones and how they all interact and flow within the plant.

As i started to understand the basics of the system i realized how this info shed light on a lot of strange behavior i have seen in cannabis through the years.

Understanding what‘s happening with hormones in plants is similar to understanding what’s happening with the hormones in humans with thyroid disease for example or teenagers as a more universal one.

 It’s another possible tool in the toolbox that helps us find them keepers.

The problem is the barriers mentioned at the top of the page, and this is where i could use some help from other people who see the worth in such information.

We can help each other discern whether or not we have a plant with the botanical equivalent of an endocrine disorder instead of doing what most other cannabis researchers have with this subject.

 
Plant Hormone Overview:

Brassinosteroids – [boss hormones, essentially a plants central nervous system] – A group of over 40(growing rapidly) chemical messengers that communicate with and control the Hormones listed below. This group controls all growth as well as the “immune system” a loose term describing defense mechanisms designed by plants over time. These hormones form and control a system of communication in plants.

 
Flower Growth Hormone Group: Hormones controling growth who exclusively communicate with each other via the Brassinosteroid System(BS).

Florigen – [the annual flower hormone] – Enables short day plants to measure darkness and tell the plant when to flower using the BS.

Auxin – [rooting hormone,mutation hormone] – Responsible for cell division in root tips and new growth tips. Controls apical dominance by regulating the ability of itself to be mobile within the plant using the BS.

Cytokinin – [growth hormone, plant HGH, mutation hormone] – In abundance and flowing freely this hormone makes every part of the plant larger throughout all stages of growth. It does not speed flowering as commonly believed, but it does make flowers larger. Also playing a role in cell division aside Auxin it comes with the risk of mistakes in the copying process and leading to possible mutations. This hormone is also responsible for male flowers appearing on female flowers in dioecious species and the male part of flowers(stamen) in monoecious species.

 
Flower Ripening Hormone Group: Hormones related to maturation who exclusively communicate with each other via the BS.

Ethylene – [female hormone, ripening hormone] – Responsible for female flowers, fast flowering and maturation of the plant through the BS.

Abscisin – [stress hormone, death hormone] – Stops cell division and closes stomata. This hormone triggers what is referred to as plant hibernation where the plant uses the BS to assess its situation and decide if it will attempt a recovery from the stress endured or give up and stay in hibernation and perish.

Gibberellin – [male hormone/plant testosterone] – Responsible for male flowers, rapid growth, long internodes and short life cycle by triggering
Abscisin through the BS. Male pollen used from high Gibberellin plants on females creates 99% feminine offspring in the resulting seed.

 
I really hope this outline is dwarfed by what others find and starts a thread that goes on for pages in the future and helps us all understand the plants we all love a little better.

Hey wow this could get interesting! Awsome ghread! Hey so which direction would you like to move into first? Im am also interested in this and use various plant hormones ( not from a bottle) at different times throughout a plants life to enhance things during the grow... Oh I don't even know where to start lol. 
Do we wanna talk about sources of the ones above? When and why to add them? Or are you more interested in  how the systems work and what hormones the play what role? 
I want to add to this topic but don't know where to start my friend!?
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#3
This is somewhat a side note but do you think it's possible to raise certain hormones in a plant to force it to flower? Or ensure a sensimilla crop maybe? Or influence a plants sex before maturity? 
I'm doing some home work to make sure I know what I'm talking about... But I plan on telling you what I know about this and some things I've observed happening... I am no expert on the matter but I do use things to increase hormones be it snapping branchs and topping or sst , coconut water , malt barley, or forcing flower or rooting clones... It all has to do with hormones and the BS!
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#4
@jrj On forcing flowers what has worked best for me is sticking thumbtacks into the base of the main stem. The flowers develop a little faster(cut a week off) and they seemed more resinous than normal. I'm usually not in a rush so i've only done it a few times, but it did work.

Sex determination in a seedling is influenced by so many things but the main factor seems to be temperature, cant remember the specifics right now but studies have shown that controlling seedling temps influences sex.

Sensi crops is a decent inquiry, we know hormones are the name of the game here but selection of solid plants seems to be the proper path. Hopefully we can get more eyeballs looking into this subject so we can use what we learn to make better more informed selections.

I'm currently going through my copy of Marijuana Botany and compiling the info R.C.C. has in there relating to this subject and will be adding it here when i'm done. Thanks for participating j.
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#5
Hormones, Enzymes and Mutations, quoted from Marijuana Botany by R.C. Clarke.

Note: I may be pushing the limits of copyright with this, but i think it falls within the parameters set forth in the front matter section of the book. “No part of this book can be reproduced or transmitted in any form or by any means,”” without written permission from the author or the publisher except for the inclusion of brief quotations in a review.”

 Marijuana Botany is THE resource for anyone serious about cannabis research. It’s cheap at around $20, it’s a quick read at 150 pgs, it’s scientific yet readable, was published in ’81 and is still relevant today. If there is a modern book that has expanded on Rob’s great work, i would like to know about it. When doing this it was funny to realize the last sentence Clarke wrote on the subject we are covering here, it seems few listened to him(got my eyes on you silver sprayers). If you’re frustrated by context missing from the information below, i suggest you read the book.

Page 16:

Hormonal changes associated with seeding definitely affect all metabolic processes within the plant including cannabinoid biosynthesis. The exact nature of these changes is unknown but probably involves imbalance in the enzymatic systems controlling cannabinoid production.

Page 28 - 29:

The physiological basis for root initiation is well understood and allows many advantageous modifications of rooting systems. Natural plant growth substances such as auxins, cytokinins, and gibberellins are certainly responsible for the control of root initiation and the rate of root formation. Auxins are considered the most influential. Auxins and other growth substances are involved in the control of virtually all plant processes: stem growth, root formation, lateral bud inhibition, floral maturation, fruit development, and determination of sex. Great care is exercised in application of artificial growth substances so that detrimental conflicting reactions in addition to rooting do not occur. Auxins seem to affect most related plant species in the same way, but the mechanism of this action is not yet fully understood.

Many synthetic compounds have been shown to have auxin activity and are commercially available, such as napthaleneacetic acid (NAA), indolebutyric acid (IBA), and 2,4-dichlorophenoxyacetic acid (2,4 DPA), but only indoleacetic acid has been isolated from plants. Naturally occurring auxin is formed mainly in the apical shoot meristem and young leaves. It moves downward after its formation at the growing shoot tip, but massive concentrations of auxins in rooting solutions will force travel up the vascular tissue. Knowledge of the physiology of auxins has led to practical applications in rooting cuttings. It was shown originally by Went and later by Thimann and Went that auxins promote adventitious root formation in stem cuttings. Since application of natural or synthetic auxin seems to stimulate adventitious root formation in many plants, it is assumed that auxin levels are associated with the formation of root initials. Further research by Warmke and Warmke (1950) suggested that the levels of auxin may determine whether adventitious roots or shoots are formed, with high auxin levels promoting root growth and low levels favoring shoots.
  
Page 30:

Cytokinins are chemical compounds that stimulate cell growth. In stem cuttings, cytokinins suppress root growth and stimulate bud growth. This is the opposite of the reaction caused by auxins, suggesting that a natural balance of the two may be responsible for regulating normal plant growth. Skoog discusses the use of solutions of equal concentrations of auxins and cytokinins to promote the growth of undifferentiated callus tissues. This may provide a handy source of undifferentiated material for cellular cloning.

Page 31:

Etiolation is the growth of stem tissue in total darkness to increase the possibility of root initiation. Starch levels drop, strengthening tissues and fibers begin to soften, cell wall thickness decreases, vascular tissue is diminished, auxin levels rise, and undifferentiated tissue begins to form. These conditions are very conducive to the initiation of root growth. If the light cycle can be controlled, whole plants can be subjected to etiolation, but usually single limbs are selected for cloning and wrapped for several inches just above the area where the cutting will be taken. This is done 2 weeks prior to rooting. The etiolated end may then be unwrapped and inserted into the rooting medium. Various methods of layers and cuttings rooted below soil level rely in part on the effects of etiolation.

Girdling a stem by cutting the phloem with a knife or crushing it with a twisted wire may block the downward mobility of carbohydrates and auxin and rooting cofactors, raising the concentration of these valuable components of root initiation above the girdle.

Page 33:

After shoots are selected and prepared for cloning, they are treated and placed in the rooting medium. Since the discovery in 1934 that auxins such as IAA stimulate the production of adventitious roots, and the subsequent discovery that the application of synthetic auxins such as NAA increase the rate of root production, many new techniques of treatment have appeared. It has been found that mixtures of growth regulators are often more effective than one alone. IAA and NAA are often combined with a small percentage of certain phenoxy compounds and fungicides in commercial preparations. Many growth regulators deteriorate rapidly, and fresh solutions are made up as needed. Treatments with vitamin B1 (thiamin) seem to help roots grow, but no inductive effect has been noticed. As soon as roots emerge, nutrients are necessary; the shoot cannot maintain growth for long on its own reserves. A complete compliment of nutrients in the rooting medium certainly helps root growth; nitrogen is especially beneficial. Cuttings are extremely susceptible to fungus attack, and conditions conducive to rooting are also favorable to the growth of fungus.
 
 
Page 36:

Layering differs from cutting because rooting occurs while the shoot is still attached to the parent. Rooting is initiated in layering by various stem treatments which interrupt the downward flow of photosynthates (products of photosynthesis) from the shoot tip. This causes the accumulation of auxins, carbohydrates and other growth factors. Rooting occurs in this treated area even though the layer remains attached to the parent.

Page 42:

Auxin produced in the tip meristem travels down the stem and inhibits. When the meristem is removed, the auxin is no longer produced and branching may proceed uninhibited. Plants that are normally very tall and stringy can be kept short and bushy by meristem pruning. Removing meristems also removes the newly formed tissues near the meristem that react to changing environmental stimuli and induce flowering. Pruning during the early part of the growth cycle will have little effect on flowering, but plants that are pruned late in life, supposedly to promote branching and floral growth, will often flower late of fail to flower at all. This happens because the meristemic tissue responsible for sensing change has been removed and the plant does not measure that it is the time of the year to flower. Plants will usually mature fastest if they are allowed to grow and develop without interference from pruning.

Page 44:

Tying plants over allows more light to strike the plant, promoting axial growth. Crimping stems and bending them over results in more light exposure as well as inhibiting the flow of auxin down the stem from the tip. Once again, as with meristem removal, this promotes axial growth.

Page 64 - 65:

Limitation of genetic diversity is certain to result from concerted inbreeding for uniformity. Should inbred cannabis be attacked by some previously unknown pest or disease, this genetic uniformity could prove disastrous due to potentially resistant diverse genotypes having been dropped from the population. If this genetic compliment of resistance cannot be reclaimed from primitive parental material, resistance cannot be introduced into the ravaged population. There may also be currently unrecognized favorable traits which could be irretrievably dropped from the cannabis gene pool. Human intervention can create new phenotypes by selecting and recombining existing genetic variety, but only nature can create variety in the gene pool itself, through the slow process of random mutation. 

Page 70:

It is important to remember that parental weaknesses are transmitted to offspring as well as strengths. Because of this, the most vigorous, healthy plants are always used for hybrid crosses.

Also, sports (plants or parts of plants carrying and expressing spontaneous mutations) most easily transmit mutant genes to the offspring if they are used as pollen parents. If the parents represent diverse gene pools, hybrid vigor results because dominant genes tend to carry valuable traits and the differing dominant genes inherited from each parent mask recessive traits inherited from the other. This gives rise to particularly large, healthy individuals. To increase hybrid vigor in offspring, parents of different geographic origins are selected since they will probably represent more diverse gene pools.

 Page 78:

Galoch (1978) indicated that gibberellic acid (GA3) promoted stamen production while indoleacetic acid (IAA), ethrel, and kinetin promoted pistil production in prefloral dioecious cannabis. Sex alteration has several useful applications. Most importantly, if only one parent expressing a desirable trait can be found, it is difficult to perform a cross unless it happens to be a hermaphrodite plant. Hormones might be used to change the sex of a cutting from the desirable plant, and this cutting used to mate with it. This is most easily accomplished by changing a pistillate cutting to a staminate (pollen) parent, using a spray of 100ppm gibberellic acid in water each day for 5 consecutive days.  Within 2 weeks staminate flowers may appear. Pollen can then be collected for selfing with the pistillate parent. Offspring from the cross should also be mostly pistillate since the breeder is selfing for pistillate sexuality. Staminate parents reversed to pistillate floral production make inferior seed-parents since few pistillate flowers and seeds are formed.

Sex reversal for breeding can also be accomplished by mutilation and by photoperiod alteration. A well-rooted, flourishing cutting from the parent plant is pruned back to 25% of its original size and stripped of all its remaining flowers. New growth will appear within a few days, and several flowers of reversed sexual type often appear. Flowers of the unwanted sex are removed until the cutting is needed for fertilization. Extremely short light cycles (6-8 hour photoperiod) can also cause sex reversal. However, this process takes longer and is much more difficult to perform in the field.

Page 87:

The proper pistillate hermaphrodite pollen-parent is one which has grown as a pure pistillate plant and at the end of the season, or under artificial environmental stress, begins to develop a very few staminate flowers. If pollen from these few staminate flowers forming on a pistillate plant is applied to a pure pistillate seed parent, the resulting F1 generation should be almost all pistillate with only a few pistillate hermaphrodites. This will also be the case if the selected pistillate hermaphrodite pollen source is selfed and bears its own seeds. Remember that a selfed hermaphrodite gives rise to more hermaphrodites, but a selfed pistillate plant that has given rise to a limited number of staminate flowers in response to environmental stresses should give rise to nearly all pistillate offspring. The F1 offspring may have a slight tendency to produce a few staminate flowers under further environmental stress and these are used to produce F2 seed. A monoecious strain produces 95+% plants with many pistillate and staminate flowers, but a dioecious strain produces 95+% pure pistillate or staminate plants. A plant from a dioecious strain with a few intersexual flowers is a pistillate or staminate hermaphrodite. Therefore, the difference between monoecism and hermaphrodism is one of degree, determined by genetics and environment.

Crosses may also be performed to produce nearly all staminate offspring. This is accomplished by crossing a pure staminate plant with a staminate plant that has produced a few pistillate flowers due to environmental stress, or selfing the latter plant. It is readily apparent that in the wild this is not a likely possibility. Very few staminate plants live long enough to produce pistillate flowers, and when this does happen the number of seeds produced is limited to the few pistillate flowers that occur. In the case of a pistillate hermaphrodite, it may produce only a few staminate flowers, but each of these may produce thousands of pollen grains, any one of which may fertilize one of the plentiful pistillate flowers, producing a seed. This is another reason that natural cannabis populations tend toward predominately pistillate and pistillate hermaphrodite plants. Artificial hermaphrodites can be produced by hormone sprays, mutilation, and altered light cycles. These should prove most useful for fixing traits and sexual type.

Drug strains are selected for strong dioecious tendencies. Some breeders select strains with a sex ratio more nearly approaching one than a strain with a high pistillate sex ratio. They believe this reduces the chances of pistillate plants turning hermaphrodite later in the season.

Page 88:

Leaf traits vary greatly from strain to strain in addition to these regularly occurring variations in leaves, there are a number of mutations and possible traits in leaf shape. It may turn out that leaf shape is correlated with other traits in cannabis. Broad leaflets might be associated with a low calyx-to-leaf ratio and narrow leaflets might be associated with a high calyx-to-leaf ratio. If this is the case, early selection of seedlings by leaflet shape could determine the character of the flowering clusters at harvest. Both compound and webbed-leaf variations seem to be hereditary, as are general leaf characteristics. A breeder may wish to develop a unique leaf shape for an ornamental strain or increase leaf yield for pulp production.

A peculiar leaf mutation was reported from and F1-Columbian plant in which 2 leaves on the plant, at the time of flowering, developed floral clusters of 5-10 pistillate calyxes at the intersection of the leaflet array and the petiole attachment, on the adaxial (top) side of the leaf. One of these clusters developed a partial staminate flower but fertilization was unsuccessful. It is unknown if this mutation is hereditary.
From Afghanistan, another example has been observed with several small floral clusters along the petioles of many of the large primary leaves.

Page 95:

It is difficult to say how many genes might control THC-acid synthesis. Genetic control of the biosynthetic pathway could occur at many points through the action of enzymes controlling each individual reaction. It is generally accepted that drug strains have an enzyme system which quickly converts CBD-acid to THC-acid, favoring THC-acid accumulation. Fiber strains lack this enzyme activity, so CBD-acid accumulation is favored since there is little conversion to THC-acid. These same enzyme systems are probably also sensitive to changes in heat and light.
It is supposed that variations in the type of high associated with different strains of cannabis result from varying levels of cannabinoids. THC is the primary psychoactive ingredient which is acted upon synergistically by small amounts of CBN, CBD, and other accessory cannabinoids. Terpenes and other aromatic constituents of cannabis might also potentiate or suppress the effect of THC. We know that cannabinoid levels may be used to establish cannabinoid phenotypes and that these phenotypes are passed on from parent to offspring. Therefore, cannabinoid levels are in part determined by genes. To accurately characterize highs from various individuals and establish criteria for breeding strains with particular cannabinoid contents, an accurate and easy method is needed for measuring cannabinoid levels in prospective parents.  Inheritance and expression of cannabinoid chemotype is certainly complex. 

Page 132 - 134:

Conversion of CBD acid to THC acid is the single most important reaction with respect to physchoactivity in the entire pathway and the one about which we know the most. Personal communication with Raphael Mechoulam has centered around the roll of ultraviolet light in the biosynthesis of THC acids and minor cannabinoids. In the laboratory, Mechoulam has converted CBD acid to THC acids by exposing a solution of CBD acid in n-hexane to ultraviolet light of 235-285 nm. for up to 48 hours. This reaction uses atmospheric oxygen molecules (O2) and is irreversible; however, the yield of the conversion is only about 15% THC acid, and some of the products formed in the laboratory experiment do not occur in living specimens.

Environmental conditions influence cannabanoid biosynthesis by modifying enzymatic systems and the resultant potency of cannabis. High altitude environments are often more arid and exposed to more intense sunlight than lower environments. Recent studies by Mobarak and others (1978) of cannabis grown in Afghanistan at 1300 meters (4350 feet) elevation show that significantly more propyl cannabinoids are formed than the respective pentyl homologs. Other strains from this area of Asia have also exhibited the presence of propyl cannabinoids, but it cannot be discounted that altitude might influence which path of cannabinoid biosynthesis is favored. Aridity favors resin production and total cannabinoid production; however, it is unknown whether arid conditions promote THC production specifically. It is suspected that increased ultraviolet radiation might affect cannabinoid production directly. Ultraviolet light participates in the biosynthesis of THC acids from CBD acids, the conversion of CBC acids to CCY acids, and the conversion of CBD acids to CBS acids. However, it is unknown whether increased ultraviolet light might shift cannabinoid synthesis from pentyl to propyl pathways or influence the production of THC acid or CBC acid instead of CBD acid.

Page 149 - 150:

Extremes and nutrient concentrations are considered influential in both the sex determination and floral development of cannabis. High nitrogen levels in the soil during the seedling stage seem to favor pistillate plants, but high nitrogen levels during flowering often result in delayed maturation and excessive leafing in the floral clusters. Phosphorous and potassium are both vital to the floral maturation of cannabis. High-phosphorous fertilizers know as “Bloom Boosters” are available, and these have been shown to accelerate flowering in some plants. However, cannabis plants are easily burned with high-phosphorous fertilizers since they are usually very acidic. A safer method for the plant is the use of natural phosphorous sources, such as colloidal phosphate, rock phosphate, or bone meal; these tend to cause less shock in the maturing plant. They are a source of phosphorous that is readily available as well as long-term in effect. Chemical fertilizers sometimes produce floral clusters with a metallic, salty flavor. Extremes in nutrient levels usually affect the growth of the entire plant in an adverse way.

Hormones, such as gibberellic acid, ethylene, cytokinins, and auxins, are readily available and can produce some strange effects. They can stimulate flowering in some cases, but they also stimulate sex reversal. Plant physiology is not simple, and results are usually unpredictable.
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#6
Thank you Elka I'ma go back and re read this a couple times... Great stuff
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