Hollow stemed, has DJshort got it all wrong??

in DJ shorts writings about breeding he says to select for hollow stemmed cultivars as they are more drug type while hemp is pith filled stems. Also Rob Clarke I do believe says similar things in his botany books. Could this be a bad assumption? or perhaps selecting hollow stemed males was to keep vigor alive by crossing 2 genetically different varieties??(less drug type X drug type=vigor but perhaps not cannibinoid %increase)

While doing some reading it appears that may actually be the exact opposite?? pith filled are drug types and hollow stems are fibre based. So this myth may have put us behind in breeding selection!! unless there is other reasons, but from what I recall him saying and in his writings I think he may have it wrong!

See pg 295. https://www.hort.purdue.edu/newcrop/ncnu02/pdf/small.pdf


"Fig. 12. Cross sections of stems at internodes of a
fiber plant (left) and of a narcotic plant (right). Fiber
cultivars have stems that are more hollow at the internodes,
i.e. less wood, since this allows more energy to
be directed into the production of bark fiber.

Love to get to the bottom of this. I realize I may catch some flack here, but i assume the researchers actually have more experience growing hemp then just drug cultivars..

Maybe Chimera can drop somethin to clear this up...

not quite sure why dj short is regarded so highly. he created the blue lines, which is great. but even those are highly unstable, hermy prone and plenty of mutants thrown in.
hollow stems/solidstems have no correlation to the final product. most of the clone only plants I have grown have solid stems. some are hollow. the hollow stemmed where no better than the solids. kinda like saying you should select for big leaves.
the only thing you will end up with is bigger leaf offspring.

Well for culling in large number of plants and choosing males which have more likelyhood of being high in thc was the idea. However It appears he had it all wrong and infact was selecting for more hemp like varieties.

I Truly hope Robert Clarke made assumptions about hemp having more pith filled stems. But at the very least we know thats what DJ says, perhaps there has been some misinterpretations of whats really happening but would love to ge tto the bottom of this. And perhaps we can change the way DJ makes his selections lol.... CHIMERAAAAA!!!

peace

I was just thinking about this subject and what DJ said etc...

In this thread https://www.icmag.com/ic/showthread.php?t=348825 they make reference to hollow stems coming from a deficiency. Sorry I don't know which post #.

that could be possible but we are just talking about healthy plants and not extreme cases as alot of weird things can happen in extreme cases colors shapes lengths etc etc.

The real truth is good plants can be found in any shape size or form... Now certain lines (blueberry) for example could be bred/worked for certain traits over the years like dj did with bb, so if I was growing anything related id keep a mental note to look for the hollow stems, but comment like That shouldn't be taken so factually, don't discard any plants based off stem fiber, many other factors come into play to like style dwc hydro plants are normally much more likely to have straws for stems the a dirt plant

Boron deficiency can cause hollow stems is what I read from Cray, I can see this being possible, low boron = low calcium uptake which makes weaker cells, I just don't have proof that it makes pith disappear or affects the vascular system as such.

I had also read that Hemp makes varieties with hollow stems and drug types are more often hollow with pith. I am not sure if it is a good selection basis or not, I have not grown thousands of plants to see progeny tests of what happens. Skunkman would be the person I would start to ask if I was really wanting to know, Chimera would also be good to ask. Not sure how easy it is to get a hold of Robert Clarke.

It seems like people find more keepers in the modern seeds then they did in the packs of seeds from the old school breeders. The modern combiners of elites and keeper finds are producing more keepers.

iTarzan said:

It seems like people find more keepers in the modern seeds then they did in the packs of seeds from the old school breeders. The modern combiners of elites and keeper finds are producing more keepers.

Click to expand...

That’s because modern chuckers are concerned with one thing...

Flowers.

Not pith or hollow stems.

My favorite thing dj has said about breeding is how plants and their highs tend to reflect the breeders personality. Not sure if thats word for word. But in a business like ours where we tend to never meet the breed it gives me a glimpse of what type of person I’m buying seeds from.

Maybe dj was trying to grow expensive straws?

Limeygreen said:

Boron deficiency can cause hollow stems is what I read from Cray, I can see this being possible, low boron = low calcium uptake which makes weaker cells, I just don't have proof that it makes pith disappear or affects the vascular system as such.

I had also read that Hemp makes varieties with hollow stems and drug types are more often hollow with pith. I am not sure if it is a good selection basis or not, I have not grown thousands of plants to see progeny tests of what happens. Skunkman would be the person I would start to ask if I was really wanting to know, Chimera would also be good to ask. Not sure how easy it is to get a hold of Robert Clarke.

Click to expand...

I think it's genetic. I had a really nice jtr that had hollow stems but was never deficient. There was a thread on hollow stems and a discussion on why some plants have them. If I see it I will link it.

The first time I grew in coco I did not use CalMag, only Epson Salt, and all my plants ended up healthy, but with hollow stems and low yield. They also stretched like hell.
Then I bought CalMag and in the following cycle the same plants had thick stems, high yield and did not stretch as much.

I don't know if it's exactly the case of the discussion. Just an experience I had few years ago.

hollow stems are tied into quality traits for hemp fibre lines.

- bast fibre ( primary / secondary ) percentages, hurd and lignin .... many sativa plants from asia, sw asia like thai carry this trait as hemp started in this region.

You folks do realize that Dj Short has bred mostly for high, not for physical traits (like looks), and that he has stated that several times? Why do ya think berry and floral lines were outcrossed to so many other variety's... the effect they pass seems mostly "dominant"... The hollow stemmed thing was taken off a book released in '77 titled Marijuana Potency by Michael Starks, more than 40 years ago, maybe a stoner myth, maybe a physical marker in some crosses?

"We" are breeding pretty resinous flowers full of "keepers" but how many flowers (not hash) do really get ya high after 2/3 bowls in a row, more than 30 minutes, or even after a week or two without having to consume more?

Our forefathers had to do things in a pretty sketchy scene (CAMP anyone?) specially for you folks in the US. With times changing at a fast pace seems we as a community are already forgetting that...

cheers

The Genetic Structure of Marijuana and Hemp

Despite its cultivation as a source of food, fibre and medicine, and its global status as the most used illicit drug, the genus Cannabis has an inconclusive taxonomic organization and evolutionary history. Drug types of Cannabis (marijuana), which contain high amounts of the psychoactive cannabinoid Δ9-tetrahydrocannabinol (THC), are used for medical purposes and as a recreational drug. Hemp types are grown for the production of seed and fibre, and contain low amounts of THC. Two species or gene pools (C. sativa and C. indica) are widely used in describing the pedigree or appearance of cultivated Cannabis plants. Using 14,031 single-nucleotide polymorphisms (SNPs) genotyped in 81 marijuana and 43 hemp samples, we show that marijuana and hemp are significantly differentiated at a genome-wide level, demonstrating that the distinction between these populations is not limited to genes underlying THC production. We find a moderate correlation between the genetic structure of marijuana strains and their reported C. sativa and C. indica ancestry and show that marijuana strain names often do not reflect a meaningful genetic identity. We also provide evidence that hemp is genetically more similar to C. indica type marijuana than to C. sativa strains.

Although the taxonomic separation of the putative taxa C. sativa and C. indica remains controversial, a vernacular taxonomy that distinguishes between “Sativa” and “Indica” strains is widespread in the marijuana community. Sativa-type plants, tall with narrow leaves, are widely believed to produce marijuana with a stimulating, cerebral psychoactive effect while Indica-type plants, short with wide leaves, are reported to produce marijuana that is sedative and relaxing. We find that the genetic structure of marijuana is in partial agreement with strain-specific ancestry estimates obtained from various online sources (Fig 2, S2 Table). We observe a moderate correlation between the positions of marijuana strains along the first principal component (PC1) of Fig 2a and reported estimates of C. sativa ancestry (Fig 2c)(r2 = 0.36; p-value = 2.62 x 10−9). This relationship is also observed for the second principal component (PC2) of Fig 1a (r2 = 0.34; p-value = 1.21 x 10−8). This observation suggests that C. sativa and C. indica may represent distinguishable pools of genetic diversity [1] but that breeding has resulted in considerable admixture between the two. While there appears to be a genetic basis for the reported ancestry of many marijuana strains, in some cases the assignment of ancestry strongly disagrees with our genotype data. For example we found that Jamaican Lambs Bread (100% reported C. sativa) was nearly identical (IBS = 0.98) to a reported 100% C. indica strain from Afghanistan. Sample mix-up cannot be excluded as a potential reason for these discrepancies, but a similar level of misclassification was found in strains obtained from Dutch coffee shops based on chemical composition [10]. The inaccuracy of reported ancestry in marijuana likely stems from the predominantly clandestine nature of Cannabis growing and breeding over the past century. Recognizing this, marijuana strains sold for medical use are often referred to as Sativa or Indica “dominant” to describe their morphological characteristics and therapeutic effects [10]. Our results suggest that the reported ancestry of some of the most common marijuana strains only partially captures their true ancestry.

We observe a putative C. indica marijuana strain from Pakistan that is genetically more similar to hemp than it is to other marijuana strains (Fig 1a). Similarly, the hemp sample CAN 37/97 clusters more closely with marijuana strains (Fig 1a). These outliers may be due to sample mix-up or their classification as hemp or marijuana may be incorrect. The sample of CAN 37/97 that we genotyped was from a Canadian hemp germplasm collection, which obtained this accession from the IPK Genebank (Gatersleben, Germany). The original source country is France but there is limited information to indicate the cultivation of CAN 37/97 as hemp. Alternatively, these samples may be true outliers and represent exceptional strains that are genetically unlike others in their group. Using the current data set, the unambiguous identification of a sample as either hemp or marijuana would be possible in the former case, but not in the latter. In any case, we find that the primary axis of genetic variation in Cannabis differentiates hemp from marijuana.

These results significantly expand our understanding of the evolution of marijuana and hemp lineages in Cannabis. Previous analyses have shown that marijuana and hemp differ in their capacity for cannabinoid biosynthesis, with marijuana possessing the BT allele coding for tetrahydrocannabinolic acid synthase and hemp typically possessing the BD allele for cannabidiolic acid synthase [7]. As well, transcriptome analysis of female flowers showed that cannabinoid pathway genes are significantly upregulated in marijuana compared to hemp, as expected from the very high THC levels in the former compared to the latter [3]. Our results indicate that the genetic differences between the two are distributed across the genome and are not restricted to loci involved in cannabinoid production. In addition, we find that levels of heterozygosity are higher in hemp than in marijuana (Fig 1b; Mann-Whitney U-test, p-value = 8.64 x 10−14), which suggests that hemp cultivars are derived from a broader genetic base than that of marijuana strains and/or that breeding among close relatives is more common in marijuana than in hemp.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4550350/

could it be that hollow stems reflect long light schedule in veg?
like 24 hour, or 18 hour disrupting hormone/cytokinin production?

just my thoughts

regarding the lighting schedule ....

hemp fibre lines - ( 15fters ), seed/flower hemp strains in the midwest usa are a little quicker than thc lines ive grown at the same latitude. these have acclimated over 60 years.

ive been searching and collecting midwest feral hemp for a few years. and the seeds collected on the fibre lines mature in early - mid September some even faster than this. thc lines ive grown generally done early-mid october at 42º latitude. bodhi g13 hybrids very quick but still not finished until oct 10th or so outdoor.

midwest US day length during growing season doesn't exceed 16 hours tho'

peaks at around 15 hours at lincoln, nebraska

http://aa.usno.navy.mil/cgi-bin/aa_durtablew.pl?form=1&year=2018&task=-1&state=NE&place=lincoln

the point I was making about hemp fibre lines in the usa.

the genetics created by the usda / lyster dewey 1900-1930 came from chinese hemp ( sativa L ) building blocks. ( longer veg and flowering times )

indeed the day length / grow season is short in the usa. but after being grown for hemp production during WWII then growing feral over 70 years the hollow stems in the fibre line I collected still have those hollow stems even with our very short growing seasons. lyster dewey was breeding for node length and hollow stems contained better fibre.

many equatorial strains will not flower by daylight hours but are triggered by time in veg - just as many sativa strains grown away from equator will not produce the same high's or quality's away from origination point like india charas lines, thai's, or columbians ...-

but what ive witnessed is this does not hold true with hemp lines regarding hollow stems. these attributes breed by usda and dewey still intact even at 42º latitude....