I am buying this for several reasons:
First off where on earth would it be natural for the sun to shine 24 hrs a day endlessly?
Nowhere.
That light cycle goes against natural laws and as pointed out above it also goes against a plants natural rhythms.

you have to think about it like it was further explained to me by the OP of that science wisdom...
We do this as well with a chemical called melatonin. your system builds up melatonin during the time you are awake and absorbs it as you sleep.
I believe that this is true and so I switched from a 24/7 light cycle to a 18/6 one
the plants immediately took off and grew faster bigger and fuller.(and not because they went into flower which they have not)
To me thats proof. A 24/7 light cycle would cause some awfully sleepy plants that are hormonally and chemically askew.
So I vote 18/6
where as not knowing before I read all that I would have thought a 24/ 7day a week schedule would promote growth better.

As far as females? I will be able to report on that once I go into flowering in about a week or so.
It convinced me just due to the sense it makes.
A pot plant makes the stuff we all want "naturally" and so a more Natural cycle would seem to fit as far as I can figure.
I am no expert by far...but I do know everything on the planet grows in rhythms plants especially and 24/7 sun with no break for a month or two is far from natural.
and would produce some very sleepy plants :P

In response to the Sativa needing more light, yes they do but stronger light not longer light. the sun sets at the equator too.

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i would call that an educated opinion/theory based on facts/science.. i like it but i think its still up to debate until a massive class action trial happens and someone can show us with proof that the ratio of males to females grown with the exact strain in the exact conditions is higher for 24 hour light than 18/6. to ensure any faults in probability i think you would need a volume of at least 50 to 100 plants for each different light cycle. I think until such an experiment is undertaken there will be constant bitching over growers who have been doing it the way they have been doing it for years and standing up for it by finding other biased opinions.

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What grow bible?

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Sex is determined by the pollen as it germinates the seed.
read this:
plant sex is determined by sperm, just like in animals. most are fert by two sperm, one sperm fert the egg and the other sperm ferts the endosperm and polar nuclei. (the endosperm is what the seedling eats for nutrients before it can photosynthesize). the sperm that ferts the egg will determine the sex of the plant.
of course you may be thinking "well then why is it that if you stress a plant youll get a hermie or whatever" wellllll in response to the stress hormone regulation is thrown off balance and allows for male phenotypic expression to show up. but you have to note, before that hormone stress, that plant was a female.

as far as isolating hormones... next to impossible. identifying hormones in a mess of other organic materials, possible, been done, many times, just cant be physically separated from the rest of the slew and be separated purely at that..

the pulp you are referring to is largely parenchyma and ground tissue. that pulp is what is referred to as totipotent and undifferentiated. basically, it can turn into anything. given that, i really dont see that happening, you might be able to turn a male into a hermie... maybe. the determining factor for the sex of the plant is the chromosomal configuration that comes from mitotic division in the pollen grain. pollen is a living plant. a living haploid plant. thats kind of hard to understand unless youre versed in plants life cycles. it an alternation of generation cycle, completely different from animals. as if you sperm could grow up and produce babies... kind of. lol.

im not going to go over the whole thing, but this is a quick run down. the actual plant that you think of, a tree for example, is considered a sporophyte. the sporophyte produces spores through meiosis. this means that there is a reduction devision in choromosomes and therefore ploidy number. the spore are what we call pollen that come from male sporangia(spore producing region of a plant) ok, here is a recap, sporophyte has a diploid chromosome number, sporangia produce spores through reduction division meiosis, which means that the spore(pollen) is haploid,and has genetic recombination for a different gene set with every one.

the pollen produces two sperm, like a said before, but unlike animals, the pollen produces these two sperm through mitotic divisions, which means the two sperm each retain their haploid chromosome nature and dont go through another reduction division.
basically this all comes down to the sperm from the pollen determine sex of the plant.
more from the biology thread by asf2j

"Femenized" seeds come from a female plant being pollinated by pollen from a hermie right?
Undoubtably the hormonal shift that takes place due to stress that causes the hermie also produces a larger number of female plant sperm (pollen)
or that would seem to be the case.

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being pedantic - the north and south poles receive 24/0 light - not a whole lot of plant growth there though

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yep - which is far better than anecdotal evidence. the male/female ratio is not discussed on the biology thread at all and i personally do not believe the light cycle has anything to do with determining sex. I personally think sex is set while a seed but can be influenced to hermie through environment but that is not from any scientific basis.

I also agree with each new study comes more evidence either for or against current theory. I was just happy to base my reasoning on sound science rather than guessing!

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yes buy not indefinitely!
The 24/0 cycle at the poles is in a natural (seasonal) rhythm as well.

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heres the science (also 2 posts up, lol)

Biology lesson.

also this:
sex is determined by the chromosomes in the sperm that fertilizes the egg.
it is true in some developing animal embryo's, such as a crocodile still in the egg, sex is determined by temperature. this is not true for most dicot plants. temperature does determine a few things that would lead us to believe it controls sex. it is important to note here the base sex of the plant is determined by chromosomes from fertilization.
there are proteins with in a plant that respond to different temps by creating what is called a "second messenger". you need to start thinking on the most basic cellular level. the second messenger is another molecule that travels into the nucleus and causes dna to turn on or off a specific gene set (note: this is not the chromosomal sex dna.) Gibberellic acid is one of the hormones produced from these second messengers changing cell metabolism and dna transcription.

studies have shown that gibberellic acid can fool with the sex of a plant. (but note once again that the original sex was determined at fertilization.) GA has been proven to grow bigger flowers but may also turn a female into a hermie. When GA is applied to a male plant, the male sporangia will grow huge, but no flowers(female) will develop.
this being said, you should be able to deduce that the original female sex can be changed (hermie), but if the original sex is male, the same technique(shifting hormone concentrations) will not "inject" as it were, female chromosomal gene information.

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why dont we make a compromise at 22/2.. thats what i used for my second batch in of two and again,, 1 male 1 female.. same as the first time indoor with 24 hour... so.....

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Totally missed that - even more awesome! So sex is determined even BEFORE the seed is formed - if i am reading this correctly.

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