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OfflineDamion5050
Perscribing Mushrooms Is Fun
Male

Registered: 03/28/10
Posts: 67
Last seen: 1 year, 8 months
Re: Question about sex of plants [Re: Fick]
    #395331 - 04/03/10 05:30 PM (9 years, 1 month ago)

I don't know a lot about the specifics for cannabis, but there seems to be some confusion among people about the process of passing along sex characteristics in general. It is simple genetics when you force a plant to hermaphrodize (is that a word?) that will give you female offspring.

Natural hermaphrodite should not be reproduced because that is a genetic flaw. The plant's genes have a defect giving it a XXY chromosome. It will potentially pass this along to nearly all of its young (I think the chance would only be 1 in 4 that it might not pass along the genetic defect since it is breeding with itself, and it might be 0% that it will not pass it on, I'd have to look more at the specifics of these plants because it depends on HOW it divides its sex chromosomes). So, if you get a hermaphrodite plant under idea growing conditions, what that plant is is a genetically defective freak and it needs to be prevented from cross-pollinating your other plants, and the seeds would most likely be more hermies. You might be able to pull the male plant parts off regularly to reduce seeding and make worthwhile buds for use, but any seeds should be discarded or you will just get more of the same.

Genetic freaks aside, a female has XX chromosomes and a male has XY chromosomes. When you breed, the odds of getting males to females (genetically) is 50/50:

X1X2+X1Y1

Results in these possible combinations in the offspring (colour coded to clarify) taking half the genetic material each from the mother and
the father:

X1X1 X1Y1 X2X1 X2Y1

In other words, 50% male and 50% female. In most species, plant and animal, males are slightly less strong genetically resulting in a slightly lower survival rate (all to do with dominant and recessive genes and a more detailed explanation is beyond the intended purpose of this message). Females being homogametic, in other words having two identical XX chromosomes, have 2 shots at overcoming flaws where their heterogametic (XY) male counterparts have only 1, where faulty genes don't have an exact corresponding "countering" gene on the other half of their sex chromosome pair. When you introduce substances, be they hormones or aspirin or something else, you are effectively weakening the already slightly less robust male genetic material (Y chromosomes) and trying to approach a survival rate of 0% for sperm (in this case in the form of pollen) that carries a Y. Obviously, this could (and probably does in most cases) also kill off weaker sperm with X chromosomes and could ALSO introduce flaws in the genes if harm is done to the female sperm that do survive - especially if extremely strong hormones are used.

When a genetically female plant is forced by a threat to its survival to turn into a hermaphrodite, it is not a true hermaphrodite genetically. It is STILL a female plant. Obviously, the fact that it has the ability to produce sperm under extreme circumstances is also a genetic trait it carries, but this is actually not a bad thing as ultimately this could be a trait that could win out in a survival of the fittest scenario in the wild. The sperm/pollen produced by the plant cannot carry anything but the genetic material of that plant itself. Since the plant is female, it does not have a Y chromosome to pass along to the eggs to produce male plants and in complete isolation the seeds cannot be anything BUT female seeds, as shown below:

X1X2+X1X2

Results in these possible combinations in the offspring (colour coded to clarify) taking each half of the genetic material for each seed from only the mother:

X1X1 X1X2 X2X1 X2X2

There are no Ys to be had to specify male characteristics. However, there IS the trait that the plant will produce pollen and self-fertilize under stress that will be passed along in an absolute MINIMUM of 50% of the seeds, depending on which part of the cannabis DNA carries that trait. In theory, if you had several females that were stressed and produced pollen and they cross fertilized, you could be actually breeding plants with an increased likelyhood of stress hermaphrodism by having this trait carried on both halves of the genetic material which is joined to make a seed. That's really only a problem if you continue to subject your future generations of plants to stress, and the only real problem for the grower is that they are going to get more seeds and less sensimilla flowers.

Ugh... well, I am sure this is a clear as mud now, but I don't know how to simplify it any more. Just remember that sex cells - eggs and sperm - are haploid cells made of half the plant's own genetic material and therefore can only have in them whatever the plant has for DNA. Join the haploid egg and sperm together and you get a diploid cell which hopefully results in a viable offspring carrying half of each parent's DNA. One parent, or asexual reproduction, means that the offspring can only contain the DNA of that single parent (although potentially in slightly different arrangements as shown above).

It is pretty ridiculous for anyone to suggest you are somehow weakening the plants to do any of this, except perhaps if you go overboard on screwing with hormones and actually do genetic damage. Using aspirin or whatever is technically simply culling male-chromosome carrying sperm and realistically means you are ensuring only the strongest sperm survive, which usually is a positive thing. Forcing plants to self-pollinate with stress is simply reproducing a trait which is already there in that plant's offspring. As long as you don't stress the plants that grow from the seeds produced this way, you aren't changing anything other than the rearrangement of the DNA configuration - which is what happens every time a plant reproduces sexually anyway.


--------------------
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Edited by Damion5050 (04/03/10 05:35 PM)


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OfflineUnion420
Horticulturist

Registered: 03/04/10
Posts: 94
Loc: New World
Last seen: 9 years, 1 month
Re: Question about sex of plants [Re: Damion5050]
    #395464 - 04/03/10 09:23 PM (9 years, 1 month ago)

I dont have the energy to post a whole shit ton here even tho its needed but I will say this. Think of every normal seed that is a seed from a female plant that was pollinated by a male plant to be 50/50, from there enviroment plays a large role in what sex that seed will turn out to be.

For instance a plant grown from seed in stressfull conditions or male encouraging conditions will most likely become a male or later on hermie if its already in the genetics somewhere. If a seed is grown in female friendly conditions it will have a much better chance of becoming a female.

The best way to feminize seeds is NOT to use the stress tecniques like light stress ect ect. You should, like said, pick a female that has been tested under herm inducing conditions that dosent express herm tendencies, this said female is then sprayed with STS or CS or GA, it will then be forced to produce bananas which then will lead to pollination and seeds, these seeds will produce females %100 percent of the time with no hermies or males if grown properly where the other ways will not like light stress, yes its easy but its the wrong way to do it.

Also, if you use the pollen from a forced herm (using the right way to herm)and pollinate a female plant that hasent been tested for herm tendencies your end result may not be %100 females unless that female was also tested for tendencies, like if you herm say skunk1 and pollinate blueberry but the blueberry wasent tested first then you may get female seeds with hermie tendencies.

I think it should be noted that probly the most important thing to remember when starting from seed is to use an environment that encourages females in any case whether using fem seeds or regular.
these conditions include but aparently arent limited to:
Less hours of light encourage females ex:14hours changing to 16 upon preflowers
More nitrogen makes more fems
Lower temps and higher humidity increase fems
Even growing medium moisture increase fems
The enviromental conditions start influencing sex the moment a plant grown from seed has 3 pairs of true leaves so it is advised to start these conditions when the seed sprouts and if desired light can be increased to whatever I use 16 when you confirm sex of the plants by the preflowers which will emerge around 6 to 8 weeks after the seed sprouts or around there.

Guess I got going huh lol, o well.


--------------------
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Edited by Union420 (04/07/10 08:26 PM)


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OfflineBuddy Guy
Gone Rogue


Registered: 02/21/10
Posts: 196
Loc: Unknown
Last seen: 8 years, 7 months
Re: Question about sex of plants [Re: FarBeyondDriven]
    #395678 - 04/04/10 09:24 AM (9 years, 1 month ago)

Intersexuality is a trait that can be expressed due to a number of reasons both genetic and environmental. 
There are hermaphrodites that are strictly genetic which means these plants have inherited a gene from one (or both) of their parents that triggers the hermaphrodite condition even in a more than optimal growing environment. Negative selection against these plants is
practiced by breeders and growers (me) in order to weed out the hermaphrodite trait from the breeding population.
Also, for example, Intersexuality can also be induced by the cannabis's grower as a result of an inconsistant grow environment.
For example, an inconsistent photo-period (light cycle), nutrient toxicities and deficiencies, PH problems, or drastically fluctuating temperatures during budding.
These induced stressed conditions causes changes in the levels of a
plant hormone called ethylene.
Ethylene is one of only a few known plant hormones and plays many
developmental roles across a range of species.
In cannabis one of ethylene's major roles is the way it is involved in the determination of sex.
Ethylene regulates which flowers should be produced stamen or pistil. This is known because applying high enough concentrations of ethylene to staminate individuals in the budding cycle results in pistils forming.
Applying ethylene inhibiting agents to pistillate individuals as they enter budding results in stamens to form in the place of pistils. This practice can be used by breeders (me) to create feminized seeds.
All female seeds are produced by gathering pollen from one female and pollinating it to another female. Cannabis has ten pairs of chromosomes. The tenth pair of chromosomes is that which represents sex. In females the tenth pair of chromosomes is XX.
In males the tenth pair of chromosomes is XY.
Hermaphrodite's pollen is XX when you turn a male into a female using
ethylene so you can take the hermaphrodite's XX pollen and pollinate it to a female whos tenth pair of chromosomes which is XX and you
have XX/XX instead of the usual male female cross XX/XY.
The major problem with this practice is that these plants will have the same hermaphroditic tendencies.

Genotype+Environment=Phenotype.


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