About Fems! Selfing-the-self and other adventures
Recent, and not so recent, conversations about the genetic implications of ‘selfing’ cannabis to produce feminised seed led me to seek out some published journal support for the things I’ve learned informally while reading here and elsewhere on the subject. In part this is to give r
eferenced context for the questions I’m raising about reproducing the treasured Candida CD-1 but also, it seems a good opportunity to try to document what I think I know at the very surface level of breeding within female plants and producing feminised cannabis seeds.
NB: I claim no expertise, just an interest in making seeds for myself one day and a belief that it behooves me to understand some of the basics of this. The following is intended as a surface level look at an important (to me) aspect.
Female plants are either;
- Regular, (naturally occurring female offspring)
- “Out-crossed” feminised (one female plant is reversed and used to pollinate another female plant grown from separate seed - either of the same variety and keeping the varietal name, or of a different variety, creating a hybrid or polyhybrid); or,
- “S?” feminised (i.e., "selfed" S1, S2, S3 etc.- one female plant clone is reversed and used to pollinate either itself, the mother it was cloned from or one of it’s fellow clones from the same mother).
When we buy feminised seed it isn’t always known by us, the end-growers, whether that seed is out-crossed feminised or the result of selfing.
My basic and very surface-level understanding of seed making and genetics tells me that this is an important question because it can impact the results we might expect from further seed making with those seeds/plants.
This is commonly discussed in passing by folks well-versed in seed making; that Selfing can sometimes mean less vigorous plants and that selfing beyond the first selfed generation (getting to S2, S3 etc.) can bring out recessive traits not expressed in the original parent(s). In other words, what I’ve gleaned from many posts and articles I’ve read is that it’s often considered the case that
outcrossing is better for vigour and reproducing genetic stability than selfing.
That’s not to say that selfing isn’t a great thing! It’s sometimes very necessary to save some genetics and breeders will also use it because they are looking for recessive traits etc. But for us folk not necessarily wanting to breed but to reproduce our favourites and secure our own seed supply into the future, it’s good to know what we should expect.
For me this is especially true of the CBD dominant varieties because I’d be looking to keep the genetic makeup as much as possible in an effort to maintain the integrity of the cannabinoid balance.
For a long time this has led me to surmise that
if we want to work with a purchased feminised seed for further seed production then we’d always be best off to “out-cross” with another individual plant, i.e., reverse one and pollinate a
nother grown from seperate seed. (NB: this also means that if someone manages to produce pollen, that could be shared to others for the sake of pollinating other grown-from-seed plants of the same variety).
SO, here comes some of the delightful synchronicity that’s accompanied me lately.
As I said above this has become a more pressing topic to me because of the desires amongst a growing number of us to"seed increase' the CD-1 and I fairly recently sought to find some documented, hopefully peer-reviewed academic, work on it to see if there was anything published that corroborates these things cannabis breeders and preservers have known and discussed for a long time.
Lo and behold I found an article called:
“Comparing Genotypic and Phenotypic Variation of Selfed and Outcrossed Progeny of Hemp”, published in (the now open access journal)
HortScience, 55(8) August 2020.
(*They define hemp as the term used to distinguish high CBD-lowTHC plants from high THC plants but the varieties they use are not industrial hemp plants ).
Very cool of them to write a paper addressing my exact question
, don't you think? Needless to say I was pretty stoked to find it!
But wait! There’s more! The second piece of synchronous joy is that the primary variety the authors used for this small study was… drumroll please… Candida CD-1 … whaaat?
It’s been hard to contain how quietly thrilled I was about both these things (and Sy got a scatteredly excited version of all this on a call recently!) - but I had to contain it until my brain was able to finally
write finish writing this post.
One caveat I’ll share before laying out the relevant (to me) findings is that it is a very small study and I am usually circumspect about small studies when discussing the medical applications of cannabis (esp. when they are small, laboratory ones using animals or thing in tubes etc.). The authors acknowledge the size of the study as a limitation, though, and note that further and larger studies are definitely needed. Moreover, the study absolutely corroborates the real-world experience that’s been shared in all the informal discussions I’ve ever read on the subject. I therefore take it as an example of ‘canna-science’ catching up to (previously outlawed) real world experience and I don’t have any trouble accepting their findings - outside one other caveat I’ll mention in a minute (that doesn’t alter things significantly anyway).
The main take homes from this paper, for my purposes, are this;
They put it that their observations “provide genotypic and phenotypic data to support” other work in the area which shows that “selfing in cannabis induces inbreeding depression”.
“Selfing, when maternal and pollen parents are the same genotype, can result in less vigorous plants and reduced yield”.
Additionally, “selfed plants have increased homozygosity and may display deleterious recessive traits such as varigation”.
“If crossing within a [variety] is necessary … then growers should consider using two different genotypes of the [variety] to produce feminised seed and keep the [variety] name”.
So this is what I have been wanting to suggest with Candida CD-1. That pollen from a reversed genotype would be best used to pollinate a different genotype (same variety, different seed).
Final caveat: The authors’ assumption (or, what is the seed we start with?)
Helpfully, the authors also addressed that niggling ambiguity I mentioned about how we don’t necessarily know what the feminised seeds we buy
are (out-crossed or S? ). In the conclusion, the authors state that “if we make the
assumption that our Candida (CD-1) parental genotype was
not the result of selfing by the seed producer, then our observations of variegation as early as the S1 compared with the S3 in Strawberry (Jones and SIngelton, 1940) suggests inbreeeing may occur more rapidly in hemp than other crops.” (Emphasis added).
It’s a fairly significant assumption because if they were to assume the
opposite is true and that the CD-1 parental genotype
was the result of selfing, then their primary observation about the more rapid occurrence of inbreeding in hemp is rendered a little weaker. It’s not significant enough to change the implications of the paper for our purposes though, I don’t think.
One thought coming out of all this for me right now is that if anyone in the 420 circle of Candida (CD-1) lovers manages to get one of them to produce pollen (and we know it’s possible - they did it for this study!
using STS ), then folks should politely request to have some sent to them, if this is possible.
In sum, I’m not professing to know anything more sophisticated about the deeper intricacies of breeding and webs of genetics - so please don’t ask me! But at the surface I think the above is correct, broadly speaking, and very worth knowing.
The paper I've referenced is linked here:
“Comparing Genotypic and Phenotypic Variation of Selfed and Outcrossed Progeny of Hemp”, published in
HortScience, Aug 2020.
NB: I should note that a while back I reached out to the folks at MMG to ask fi the CD-1 is out-crossed feminized or S1 feminised. Nothing yet - I'll be sure to let y'all know if they ever get back to me.
Moving on, things come in threes, so it is said, and Candida (CD-1) had one final synchronous surprise in store for me that made me realise I had to make this post before I did the CD-1 harvest report. Stay tuned...
) that the amber we see late in ripening is simply the degradation of the tiny amount of THC that does exist in CBD dominant plants. Maybe... I don’t know what else it could be. That amber is an indication of CBN seems fairly certain, yes?
Looks like you had a blusterous time in your neck of the woods according to my morning weather report.
