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Kutztown, PA

In all kinds of breeding there's paradigms that don't necessarily hold water. Some of those are/were based on moral judgments, not science. For example, " It's commonly held that if you marry your first cousin any offspring would be born "naked with a belly button". I think that's been debunked by now.

So, What's the upside and downside of sib x sib and self crossing? Will all your pumpkins be born with a stem or something bad?

12/19/2022 3:52:40 PM

Grittyville, WA

The best kins seems to follow a pattern of marrying a first cousin, approximately. Its a give and take where you want to maintain some traits without selfing so much that other poor traits are propagated.

12/19/2022 5:05:00 PM

Lodi, California

Every single seed has genetic diversity, to a greater or lesser extent. Each one is unique in how genes are paired. That's why every pumpkin from a given seed is different. Sometimes it's more pronounced, sometimes less. Some seeds only produce beautiful orange pumpkins, some throw a little bit of everything.

This is important for understanding the difference between a sib and a self. A plant has more in common genetically with itself than it does with its sibling. I believe every grain of pollen is genetically different (correct me if I'm wrong) and so is every unfertilized seed. This is further increased when they are combined, as genes tend to pair in very random ways, maximizing diversity. However, typically a sibling is still very identical to its sibling, just to a lesser extent.

Onto selfing/sibbing as it pertains to good pumpkin genetics, my opinion is that a single generation of selfing can go either way, and can be positive when isolating desired traits. I'm interested in what the 2493 Wolf will produce, and I'll be growing it, since it was such a nice fruit with good qualities, but there's no telling which way it might go. However, selfing has a slight tendency toward worse due to inbreeding which results in a higher probability of bad traits rearing their head. This isn't usually seen after a single generation of inbreeding, but rather is an occurrence which is realized most notably as a result of repeated inbreeding.

12/19/2022 6:55:46 PM

Lodi, California

To be more concise, selfing produces a gene pool which is more tightly packed, producing progency which tend to be more similar to the parent. Some seeds will have traits that we think are better, and perhaps slightly more will tend to have traits that are worse. The problem with selfing and inbreeding repeatedly is this lack of diversity. Diversity is good because the cream rises to the top. If every single seed is the same, then you can't select desireable traits. We select the best seeds, cross them, and repeat. Lack of genetic diversity results in stagnation over time

12/19/2022 7:04:46 PM

Shingle Springs, CA

Both "sib x sib" and "selfing" are examples of inbreeding. "Selfing" is closer inbreeding than "sib x sib". Inbreeding basically does two things - 1) It produces offspring with a narrower gene pool than what would have been produced had inbreeding not been involved. This results in more uniformity (this is a good thing if it is done correctly and the uniformity consists of the desired phenotypes). 2) It decreases vitality or vigor. This is not a good thing, but it can be managed by controlling the level of inbreeding. The crossing of two completely unrelated parents completely restores maximum vitality.

Inbreeding doesn't create undesirable traits, it just exposes what was already there hanging out in the gene pool. Many of the undesirable traits are recessive and so you need two copies for the undesirable phenotype to be expressed. Since inbreeding narrows the gene pool (which also means it increases the frequency of the remaining alleles) it can result in the double recessive genotypes popping up more often. When inbreeding, an effort should be made to rid the gene pool of these undesirable alleles when they surface.

So, inbreeding is just a tool to help increase the frequency of desirable phenotypes. One tries to capture the good alleles and exclude the undesirable alleles in the new narrower gene pool of the next generation. Outcrossing of unrelated parents is another tool used to maintain an acceptable level of vitality. Like all tools, they can be used by craftsmen and hacks alike. The tools aren't what is good or bad, it is how they are used.

12/19/2022 10:48:22 PM

Shingle Springs, CA

The level of inbreeding in any particular plant or animal can be calculated and is known as the inbreeding coefficient. A slightly inbred plant will have more than enough vitality to survive and thrive. It takes a number of successive generations of inbreeding before vitality becomes a serious problem.

pg3(Ashton) makes a very good point above when he says "The problem with selfing and inbreeding repeatedly is this lack of diversity. Diversity is good because the cream rises to the top. If every single seed is the same, then you can't select desireable traits." One of the keys to successful inbreeding is use it along with outcrossing. The master breeder inbreeds for a number of generations until improvement starts to leveling off and then does an outcross to introduce more variation so additional improvement can be made through further inbreeding.

12/19/2022 11:04:17 PM

Syracuse, NY

Out of place or not, here are a few things I typed with cold hands and am not re-typing, lol:
---I'm not liking the term "sib X sib" unless it refers to crossing two plants that are each sprouted from already-"sib" crosses;
It is just "sib", as in 'sibling' and/or short for 'sibling';

---What it took for the 1885.5 to become a top seed was at least one big one and one orange one
in '20. No one knows for sure what a seed will produce until it is actually done.
It is only a guess until then.

---Also, have a look at the progeny of the 1385 Jutras up through the 1270 Sawtelle.
None of us are Ron Wallace, but there was no 'significant shrinkage' in the lineup, lol---eg

12/19/2022 11:35:39 PM

Bethlehem CT

Shew, are you saying that all plants including AG'exhibit a level of hybrid vigor? In years past this was a topic of much discussion and debate.

12/20/2022 8:00:00 AM

Kutztown, PA

Big Moon, I think that debate has been going on in the Biology Department for many many years. As I recall the real debate is over the theory that good allele x average allele = Excellent allele (pheno type). In other words 2 x 2 = > 4.

12/20/2022 9:03:11 AM

Shingle Springs, CA

Big Moon, I am saying that vitality or vigor is a quality of all plants and animals. It is a spectrum that ranges from very good to very poor. Inbreeding tends to reduce vigor and crossing tends to increase vigor. Maximum vigor is attained when both parents are completely unrelated.

So, taking as an example the original question posed in this thread, a flower pollinated by a sib is slightly less inbred than that same flower selfed and so the resulting seeds (and plants grown from them) will probably have a bit more vitality, statistically speaking. The difference though would probably be hard to notice, but I hope it illustrates my point that vitality is a range.

12/20/2022 10:26:03 AM

Lodi, California

Remember all the crosses with the 1625 Gantner? Those were old genetics, and they produced some big pumpkins. The outbreeding probably resulted in more vigor

12/20/2022 11:08:01 AM

Kutztown, PA

Shew, I think it would be better to say that the "potential" for maximum vigor to be expressed is proportional to the genetic variation between parents.

12/20/2022 11:35:34 AM

Western NY

Shew got it right but I don't think we can quantify vigor, at least not yet.

You're still probably better off with an awesome selfed seed than a non-awesome, random outcrossed one. If the final weight potential of a selfed seed and a non-selfed seed are equivalent, you would expect more problems (maybe) with the selfed seed - but how much more often? Let's say it's a 2% increase in problem plants. If a seed gets grown 50 times in two years (that's rare except for the top seeds), that's only one additional problem plant above baseline.

As far as comparing sib - self - or other? The unfortunate truth is that we are doing an unorganized breeding project with so many variables that it is tough to really compare. And let's be honest, in any given year there are around 100 growers (maybe closer to 50) that can really max out the genetic potential of a seed to test it out. A 10% genetic weight advantage makes a difference at 2500 vs 2750, but if I put that same seed out in my orange patch with minimal care, I'm probably not going to notice that it was 1320# instead of a 1200# patch average.

But yes, I would still rather have 1320 than 1200.

12/20/2022 11:37:05 AM

Grittyville, WA

1625 Gantner 1756 h/j and maybe the 2112 skinner are selfed seeds that seem to be genetically infallible in terms of making good out crosses. The 2469 Daletas would surely have been better as a breeder if it had been selfed? But the selfed ones dont seem to make the biggest pumpkins, its when they are skillfully (or luckily) part of a cross that they can really shine.

12/20/2022 12:58:31 PM

Kutztown, PA

Little Kins,

Your not implying that any part of this is luck are you?

12/20/2022 1:23:33 PM

Kutztown, PA

Luck comes when preparation meets opportunity. So, I guess get your patch ready and buy a good seed.

Andy, do you think 2% is close to the percentage of problem plants if all seeds from a given pumpkin were grown? What do you think a legitimate range would be eg. 2-10% problem plants. Do folks have any idea what the range might be?

12/20/2022 1:42:29 PM

Shingle Springs, CA

Garwolf, that is a better statement.

12/20/2022 2:32:49 PM

Partlow,Va

Great thread for what has been on my mind for next years planting.
This year I happened to grow two equal melons at 276lbs, from different seed lines. After reading here I think I should cross them rather than self.
What do you think of bringing the mother back and cross the daughter? Or is that not really getting you anywhere?

12/20/2022 7:08:38 PM

Bowdon, GA

Hank I would do a 276x276. That would confuse everyone lol.

12/20/2022 7:30:57 PM

Grittyville, WA

I think mother x daughter is usually a better cross than sibb x sibb. You just dont see a lot of those sibb crosses successfully making it into the pumpkin genealogy.

12/20/2022 8:17:35 PM

Brooktondale, New York

So I have been watching this thread intentently. My question is, isn't a selfed plant simply a homozygous punnett square from Gregor Mendel? A sibb would be a closely related heterozygous with many similar alleles, slightly more diverse. An "unrelated" cross would offer the most diversity, however for better or worse the most unpredictable. The real problem with trying to answer the question is how many alleles are involved. Alleles can be both good and bad so a selfed plant would enhance both equally. Would vigor not be another allele like a nice color or shape?

12/20/2022 10:12:59 PM

Grittyville, WA

Vigor often occurs when both alleles for a trait are present (heterozygous) this is why the hybridization of two inbred (homozygous) lineages is so universally successful.

However, certain traits like % hvy are probably best preserved in some of the selfed lineages, otherwise these traits would get lost. (They would only show up rarely if they were repeatedly crossed into a highly diverse gene pool.)

12/20/2022 10:34:41 PM

Grittyville, WA

Alleles/traits is lexicon that is interchangeable maybe it makes more sense to say:
"Certain alleles like % hvy are probably best preserved in some of the selfed lineages, otherwise (if continually outcrossed) these alleles would get lost."

12/20/2022 10:39:20 PM

Grittyville, WA

Anyhow to sum it up, the pendulum cant swing far towards diversity or homogeneity because in terms of getting good results, the best genetic mix always swings towards a combination of inbreeding and out crossing, in order to get the best of both worlds.

12/20/2022 10:51:30 PM

Shingle Springs, CA

Berggen, no a selfed isn't simply a homozygous punnett square. Lets pretend that we are just dealing with one gene (you are right that there are many that determine what we consider a good pumpkin) and our plant is heterozygous for that gene (we'll denote its genotype as AB). We could use a punnett square to figure the probabilities of the resulting offspring, but they would not all be the same and some would not be homozygous (1 AA, 2 AB and 1 BB). So even in the case of a single gene we can get multiple offspring genotypes (and of course phenotypes).

A sib is also not necessarily more or less heterozygous. If the parents are the result of significant inbreeding, there can be a great deal of genetic similarity between sibs; and if the parents were not related both sibs could be quite genetically different.

12/20/2022 11:18:34 PM

Shingle Springs, CA

Berggen, let me give an example of how one might apply this to pumpkins. My particular interest is in growing big pumpkins BUT I also want them to be orange and round. It is just my personal preference, but it drives my decisions about what seeds I try to acquire and grow. When the 2350 first came on the scene, I wasn't interested in them because of the green areas of the 2350. However, the next year the 2350 grew some exceptional pumpkins in that they were big and consistently orange. The fact that such a high percentage were of good color caused me to look for available seeds that were from the 2350, had excellent color AND were selfed. By selecting such a selfed seed, I have a higher probability of getting a plant homozygous for the various alleles producing good color from parents who were also large and of good shape. In my particular case, my sights are on a seed from "Ruby". Now any seed(s) I am able to get from "Ruby" will not be identical. If we could magically grow every seed "Ruby" produced, we would (in theory) get a bell curve of weights. I will of course be hoping that any "Ruby" seeds I acquire are from the far-right edge of that bell curve. Because I could be very unlucky and draw a seed from the far left, I will try to get at least two seeds. I will absolutely self the pumpkins from these seeds, because if I am lucky enough to grow a "Ruby" that turns out to be huge and of brilliant color, I want those seeds to be as homogeneous for the right color alleles as possible. Those seeds would then be a kind of genetic bank I could use going forward as I work on improving other traits.

12/20/2022 11:18:58 PM

Bethlehem CT

In case you guys don't remember these here is a link from Joze Ailts back in the day.
http://www.bigpumpkins.com/ViewArticle.asp?id=97

12/21/2022 8:18:25 AM

Bethlehem CT

and another one
http://www.bigpumpkins.com/ViewArticle.asp?id=98

12/21/2022 8:19:15 AM

Western NY

Gary - I just made up the 2% as a guesstimate to make the math easy.

I'm thinking the true number of problem plants can be way higher on some. In this scenario, I'm thinking of the 2350's heat issues, and the 2702's weak offspring, the 2517's yellow leaves. Obviously, they were all still able to grow some big ones, and the average selfed seed may not have enough planting to notice those patterns.

12/21/2022 1:40:58 PM