Methods to shorten internodes

[CannasaurusR]

I firmly believe that sexual expression in plants and humans, has a lot to do with environment from embryo to sexual maturity. With my limited experience with cannabis, high germination and high vegetation stage ambient temperature causes a high male ratio. Conversely, cool temps during veg period gives a high female ratio. Just from my little environment, anyway. I have seen a few recent studies, but I couldn't tell ya where. There is a bit grower talk on forums, bashing this one around.

 

[PoweredByLove]

biggest influence I've seen on node spacing so far is moisture of the roots. if you keep them well watered during the stretch they shouldn't stretch as much. also keeping the lights close as others have said. I would continue to give them the nitrogen through stretch. other things you can try are lst, pinching, and topping when you flip might help distribute the energy into the branches rather than the top. and keep the heat to a minimum.

 

[LostTribe]

if you are trying to limit your node spacing due to height limitations you could try humboldt bushmaster. It is supposed to stop plants from stretching at the onset of flowering.

 

[Chimera]

https://www.votehemp.com/PDF/Sex_determination_in_Hemp.pdf

Welcome to 1925 my Bro Science muchacheros.

Although the field has muddied since. X chromosome/autosome ratios are used determine sex, which are influenced environment, though this relates to intersex growth.

This is all to my current knowledge. Perhaps I've been misreading but my ego says that is unlikely.

Hirata's work is full of flaws... did you read the cited paper? He sprouted seeds in a greenhouse in December, January, June, etc. Have you ever sprouted seeds in November, December or January in a greenhouse? If you do, you will see lots of sexual abnormalities even in stable lines. Cannabis is accustomed to developing maturity in ever increasing day-lengths. This kind of out of season planting can lead to all sorts of ethylene dis-regulation and altered ethylene expression. We know that if we mess with the ethylene pathway in Cannabis, it can lead to altered sexual phenotypes; see creation of feminized seed via STS application.

Growers all want to claim they have perfect environments, but the truth of the matter is that environmental stresses can cause changes in ethyene regulation. We know for a fact that altered ethylene levels can lead to changes in staminate vs pistillate flowers expression, so it's not much of a leap to say that environmental stresses causing changes in ethylene levels is at least partially responsible for the altered expression of floral types seen in many experiments (eg Hirata, 1925) and grow rooms.


I have not seen proof that is is an X/autosome balance system responsible for gender determination, rather than an XY system. The fact of the matter is if the plant has a Y chromosome the plant is male. To me, whether the answer lies in the trigger being on the Y, or the x/autosome balance system being correct is rather academic in nature.

 

[Mikell]

I did read and note that. Some flaws were pointed out in the texts as well re: true male pollen contamination.

I linked it as an early contradiction of the belief that certain conditions can influence true sex post-germination.

I readily admit I read/understand little on genetics. Mostly summed up by the odd wiki article, if that isn't telling enough. It doesn't draw my attention in the same way pest/predator biology does.

It was my understanding X/a ratios were a somewhat current method to quantitatively prove sex. Or is that incorrect?

 

[Chimera]

Hey Mikell, I didn't mean that to sound off putting; it's certainly a paper that has been referenced often in talking about this issue. I simply meant to call attention to the experimental confounds in the methodology. It's tough to draw conclusions when you have experiemtnal conditions that could affect the outcome.

We've also come a long way in this area of research, with genetic sequencing and DNA analysis, we have already found pieces of DNA that show the presence of a Y-chromosome in cannabis.

It was my understanding X/a ratios were a somewhat current method to quantitatively prove sex. Or is that incorrect?

Plant Mol Biol. 2000 Dec;44(6):723-32.
Site-specific accumulation of a LINE-like retrotransposon in a sex chromosome of the dioecious plant Cannabis sativa. http://www.ncbi.nlm.nih.gov/pubmed/11202435

This thread adds a little more to the discussion, without going into it again here....
https://www.icmag.com/ic/showthread.php?p=7272760&posted=1#post7272760

I don't know whether the X/autosome balance "proves" sex/gender one way or another, but the current method is based on a PCR assay developed against male associated DNA sequences (or MADCs) found on the Y chromosome.

Its like I say above though, whether it ends up being the Y chromosome that possesses a trigger for male-ness, or the X/autosome balance system is the ultimate cause, the outcome in my opinion is the same (which is why I say the difference is really academic). To me it's not really important if the outcome is the same- ie Y chromosome containing plants are male, XX plants are female.

However, Kevin McKernan from Medicinal Genomics has been sequencing a series of male plant's genomes, so perhaps we will learn some more info from his work.

-Chimera