What causes autoflowers to flower?

[Son of Hobbes]

I posted this awhile back:

https://www.autoflower.org/threads/day-neutral-flowering-dnf-of-autoflowering-cannabis.83846/

And give this a general read: Flowering on time: genes that regulate the floral transition

:

 

[BII]

I get that the hormones are controlled by genetics, but I think what this idea is looking at is a way to manipulate the release of the hormones. We know environmental factors have an effect on hormones in animals, so why couldn't it in plants?

And back to the original question, "What causes autoflowers to flower?" Basically with ruderalis and autos, it's the genes that activate needed auxin/growth hormone expression at a certain time in the plant's growth (late veg./early bloom). With autos blooming time is genetically preset and is not induced/initiated by changes in the the environment, such as daily light exposure.

Autos not having their time to blooming controlled by external factors is what makes them unique and attractive vs. photo strains.

 

[GreenBean]

This makes sense and I'm guessing yield is higher for the bigger pots also.


My only idea is that constant transplanting is effectively the same as starting off with a bigger pot, but it adds more time in the veg phase. Longer grow could allow for a bigger plant. I think for this idea to have any chance of working you must have perfect transplants with minimal stunting.

Yield is bigger in a larger pot, but again certain strains will only get so big regardless in my experience. For instance one of my favorite strains is a La Berry Fruta. She doesn’t show much difference in veg/size between a 5 or 7 gallon. She’s crossed with Lowryder. Is she bigger in a 7 gallon vs a 3 gallon? Certainly.

Then you take a strain like Orange Sherbet that I’ve been experimenting with lately and the difference between 5, 7 and 10 gallon pots is remarkable. 10 gallon is almost too much.

so I would say that if the plant has the correct genetics to take advantage of the larger pot, then it will.

I guess I can understand the transplant theory. I used to transplant all of my autos without any ill effects. But personally, for me (emphasis - for me), it became inefficient to do. And I’m not a lazy grower by any means. Sometimes I might wish I was.

I’m certainly no expert at anything. I’m mostly a blundering fool who likes to experiment. It just seems to me that with the right strains, those plants will certainly differ in veg length and in turn larger yields, based on pot size. The only rational explanation I can come up with is pot size influencing the time to flower.

 

[Son of Hobbes]

Finding information on this is like a specific needle in a haystack of wrong needles, but I found this:

Flowering response of day-neutral and short-day cultivars of Nicotiana tabacum L. Interactions among roots, genotype, leaf ontogenic position and growth conditions on JSTOR

Joan S. Gebhardt, Carl N. McDaniel, Flowering response of day-neutral and short-day cultivars of Nicotiana tabacum L. Interactions among roots, genotype, leaf ontogenic position and growth conditions, Planta, Vol. 185, No. 4 (1991), pp. 513-517

www.jstor.org

Look at the upper right paragraph in the 2nd column, it briefly references that bringing the plant apex (the tallest point of the plant) close to the roots actually inhibited flowering in day neutral Nicotiana Tabacum.

So looking more at Nicotiana Tabacum, I found this:

The FT/FD-dependent initiation of flowering under long-day conditions in the day-neutral species Nicotiana tabacum originates from the facultative short-day ancestor Nicotiana tomentosiformis - PubMed

Photoperiod is an important external stimulus governing the precise timing of the floral transition in plants. Members of the FLOWERING LOCUS T (FT)-like clade of phosphatidylethanolamine-binding proteins induce this developmental process in numerous species by forming regulatory protein...

pubmed.ncbi.nlm.nih.gov

We identified several thus far unknown FT-like and FD-like genes in the genus Nicotiana and found that, even in the day-neutral species Nicotiana tabacum, floral initiation requires the photoperiod-dependent expression of several FT-like genes.

So it seems like it's possible that cannabis can potentially express both day-neutral flowering genes -and- possibly short day flowering genes?

I'm pretty sure genetic expression can be turned on and off when conditions are met.

 

[BII]

Finding information on this is like a specific needle in a haystack of wrong needles, but I found this:

Flowering response of day-neutral and short-day cultivars of Nicotiana tabacum L. Interactions among roots, genotype, leaf ontogenic position and growth conditions on JSTOR

Joan S. Gebhardt, Carl N. McDaniel, Flowering response of day-neutral and short-day cultivars of Nicotiana tabacum L. Interactions among roots, genotype, leaf ontogenic position and growth conditions, Planta, Vol. 185, No. 4 (1991), pp. 513-517

www.jstor.org

Look at the upper right paragraph in the 2nd column, it briefly references that bringing the plant apex (the tallest point of the plant) close to the roots actually inhibited flowering in day neutral Nicotiana Tabacum.

So looking more at Nicotiana Tabacum, I found this:

The FT/FD-dependent initiation of flowering under long-day conditions in the day-neutral species Nicotiana tabacum originates from the facultative short-day ancestor Nicotiana tomentosiformis - PubMed

Photoperiod is an important external stimulus governing the precise timing of the floral transition in plants. Members of the FLOWERING LOCUS T (FT)-like clade of phosphatidylethanolamine-binding proteins induce this developmental process in numerous species by forming regulatory protein...

pubmed.ncbi.nlm.nih.gov

So it seems like it's possible that cannabis can potentially express both day-neutral flowering genes -and- possibly short day flowering genes?

I'm pretty sure genetic expression can be turned on and off when conditions are met.

But is this study relevant to autos vs. photos, or cannabis vs. being tobacco-specific (which seems likely)?

Regarding:
"Look at the upper right paragraph in the 2nd column, it briefly references that bringing the plant apex (the tallest point of the plant) close to the roots actually inhibited flowering in day neutral Nicotiana Tabacum."

Isn't bringing the tallest apical bud to the ground just some extreme "low stress training?" I've (and surely many others have) tied down branches to the outside of pots such that their ends were below soil/media level, and never noticed nor expect any delay in flowering from this. If such simple LST did delay flowering in cannabis, I presume it'd be common knowledge.

 

[fryge]

some people going in a good direction here

it is indeed somewhat specific to specific plants, but there is a common network underneath it. that network can have some changed connections in different plant species, but it evolved from a common base. those papers posted in the latest posts are dealing with that, for example that stuff about FT/FD.
that tobacco paper is pretty old (1990), so I'd look for something more recent if you want up to date info (old is not always bad, but with these molecular networks a lot of it is recent)

there isn't just one thing that decides flowering. you can imagine that for a wild plant timing it's flowering well is pretty crucial to make enough seeds, and survive through evolution.
with weed plants you can for example see the difference between a plant from seed started at 12/12, and a clone immediatly put on 12/12. the plant from seed will veg for a while despite being in flower-triggering conditions. it first needs to get old enough before it will react to the trigger. while the clone has gone through it's youth already and is immediatly ready to respond to the flower trigger.

lack of root space and/or lack of nutrients are all signals to the plant that it doesn't have a lot of resources available, and it better hurry up and make some seeds before everything is gone. it also may 'decide' it's better to have a few well-developed seeds, instead of investing in lots of flowers and forming seeds, but then not have enough resources to make all those seeds into good healthy seeds. all those npollinated flowers and white/underdeveloped seeds are just a waste of resources from the plant perspective.

plants also have all kinds of pathways to perceive signals from the environment and translate those into a response. and since flower timing is so crucial, plenty of different signals plug into the network. so yes it's logical that stuff like root restriction could have an effect (and, it is known as a factor in other plants).

btw, about lst delaying flower, I do have one experience that made me wonder a bit. an autoflower from a breeder that is also on here (won't name names, just grew 1 plant so not a fair impression anyway) that behaved more like an early photo for me. might have been a case of genetics (i.e. not fully auto, and I just grew that 1 plant), but I also gave it my usual LST (and later in the season more hst) treatment.
so at the time the thought did cross my head if maybe my training had an effect on delaying flowering.

I'm pretty sure genetic expression can be turned on and off when conditions are met.

just quoting this since I had to chuckle a bit when I read it (in a good way). this is indeed exactly what is going on.
those networks I spoke about above in the end result in some protein binding to dna somewhere and turning on/off the expression. then there are all kinds of interactions, intermediary steps, etc to make sure those genes get activated exactly at the right time at the right place.

(p.s. hormones are part of those networks too, but they're just a part of it, there's more to it than just hormones)

 

[JP1]

I've done 5 and 10g outside at the same time with the same seeds and they've flowered at basically the same time. However, my 5 and 10g fabric pots are basically the same height! So no help... I'd like to see something with maybe regular pots vs tall and skinny pots with the same volume to see if it's the root but I don't think so. Personal experience is they're all basically the same, ish. Finish just seems to be sooner or later depending on volume. Seems to me like they're living things and will flower when they want to

 

[wannagrowbuds]

I've grown the same strain in a shot glass and in 5 gallon pots, both flowered at the same time. Obviously the tap root hit the bottom of the shot glass before the sprout was even above ground. Pot size does not trigger flowering.

 

[DankDoctor420]

 

[The Iconoclast]

Obviously it is literally in their DNA to flower decided by time. Having said that we are usually more interested in what causes an autoflower to finish earlier. I recently grew an auto lemon pie that took 14 weeks to finish, but I'm now growing the same bean and it is going to be finished at 11 weeks. Growing conditions were the same, so I have to look at what was different and I will hypothesise that the significantly different way I treated both plants is what caused it. Now I need to verify that, which will take some time.