From

Location

Message

Date Posted

Pumpkintown, SC

In this day and time with all the great seeds available to us, could someone "really" explain why we would want/need to make a crossback? I mean, if you want to reinforce certain genes, why not self or sibb? I truly want to know why this is as sought after a crossing plan as it is.
Ok. Your turn, BF

1/18/2005 8:13:41 PM

Greencastle, PA

Say you have an YYY x ZZZ.... now, you want to reinforce the ZZZ genes. If you self the YYY x ZZZ you'll get a mixture of the two, wheras crossing it back to the ZZZ reinforces only that strain.
Tom

1/18/2005 8:49:22 PM

Pumpkintown, SC

Thanks for the reponse Tom. I understand your example but I meant selfing or sibbing the seed itself that you want to reinforce. In your example, selfing or sibbing the ZZZ. BF

1/18/2005 8:56:52 PM

Minnesota(dw447@fastmail.fm)

Snake oil,
I was thinking of asking the same question.
What is the thinking behind this?
Example:
845 X 846, then cross the 845 back into this.
You'd end up with 1/4 846 genes and 3/4 845 genes, correct?
Is this the only objective? Is there something I'm missing here, that may enhance the genetics? It seems to be a popular breeding stragey, I'm just wondering what makes it so popular?

Doug

1/18/2005 9:36:54 PM

Oakland, CA, USA

Doug, each one of the seeds of the first cross would have a different specific mixture of the genes (50/50 from each parent, but what specific genes make up that 50%?) and so back-crossing could be a useful tool to either "try again" to fix in a trait that was missed on the initial cross, or try to bring out recessive genes from one parent, or to reduce the genetic variability in the next generation, to try to "fix" a desireable trait. Maybe you don't want all 50% of one parent's genes, just the part that codes for heat tolerance, or good color, or round shape, so you cross back to the parent that had a whole bunch of other good qualities, but always put out beanbags, or pale pasty fruit, or couldn't take an 85 degree day. Of course, for back-crossing to be a truly effective tool in a robust breeding program, you'd have to grow out all (or an awful lot) of the seed from both the first generation pumpkin and then from all (or an awful lot) of the pumpkins of the second generation plants. Approximately 400-600 plants from the first generation plant, and then 400-600 from each of the second generation plants that make it to maturity! The problem with using these and other sound, well-established breeding techniques in giant pumpkins is that they rely on probabilities and that means large numbers of individuals (or plants) and not many have the resources to plant out and evaluate all the seed from a single pumpkin in one year. I think you are correct to be suspicious of the utility of this technique for our purposes. Thanks for asking about that, it made me really think it out and I learned alot in the process! -Erin.

1/18/2005 11:25:17 PM

Pumpkintown, SC

Thanks Erin for the post. Good example of the "try again" and/or "fix" reasons for a crossback. Although correctly referred to as a "sound, well-established breeding technique," I personally would say the factor weighing in heaviest here(pun intended) is the true lack of probability for characteristics being sought, being obtained with such a cross(esp. for us AG growers). Agree...disagree? BF

1/18/2005 11:55:57 PM

Indiana

the 805 pukos is a form of a backcross. I look at backcrosses as a new and improved version of the reinforced line. The 805 Pukos is a new and improved 935 Lloyd. Thats why I like the 229 Hathorn for squash. As far as I am concerned it is a green version of the 805 Pukos.

Anyway I am working on several second generation crossbacks that I think have lots of potential. To me the second generation will make or break the theory as a means of improvement. If the second generations arent better than the first, I am going to look at it as another means of inbreeding.

Tom

1/19/2005 12:25:09 AM

Pumpkintown, SC

Yep. This is an angle I was wondering if anyone was working. This is opposite of how most approach crossbacks(I believe). I too am interested in this form of crossing/crossbacks. BF

1/19/2005 1:58:58 AM

Oakland, CA, USA

Snake Oil, I agree that the point of back-crossing is to lower the random nature of inheritance to manageable levels of probability, but you have to know that the desired gene was passed on to make it worth bothering with the cross. You will have to grow the plant and fruit all the way to maturity before knowing if it's worth back-crossing, at which point you'll have to clone it and use it next year for genetics purposes. Or I guess you could just cross it anyway and see at the end of the season if it's worth using those seeds next year.

Tom- What kind of improvement are you looking for in your second generation plants? Just curious what you are selecting for and looking for. I know you've been doing this for a while, I'd love to get a chance to pick your brain on pumpkin breeding some time.
-Erin.

1/19/2005 2:38:07 AM

Long Island,New York

Backcrossing and selfing/sibbing as an attempt to make something one step closer to a desired goal is , at best, an educated stall tactic just because we dont know what we have (as far as what genes are expressed in that particular plant) until the plant is basicly done. (when we try and breed for big anyway).When I want my seed to be as close to the planted seed in characteristics and performance potential I sib-- and hope that both my planted parents exhibit the characteristics that that seed is known for--and that those characteristics are inheritable--and of course that they are in fact inherited.
When I want to keep the genes stable I self it. When I think I can bring out the green I will self it. When I want to keep a 10 yr old seed line alive I will self or sib (if room is available for that second plant).
Not much of this is optimized without growing numerous plants of the same seed, selecting only those that exhibit the characteristics you want, and breeding them.
I think there's many ways to look at this.....
Its amazing how well we have done with such a random breeding technique...up almost every year in wts.
Its amazing to think how heavy we would be if we actually did it right.
Being a hobby for most, there's nothing wrong with what we do. Who says we have to be real breeders?
Its interesting how we micro-manage everything but the breeding technique itself.....but without room for 250 plants thats cool, its a hobby for fun isn't it?
I find it particularly humerous how breeders laugh at us yet never manage to walk away from a conversation not learning anything new from us or realizing "oh, THATS why its done that way"....we can learn from them like they learn from us, and we do better with what we have than they will ever do because we love what we do and we're so anal about it. (thats a good thing)

1/19/2005 8:20:45 AM

Long Island,New York

Best bet if you dont have 250 plantsites?...grow the seed out...keep a clone if it has what your looking for....breed with the clone next year...then grow that seed...rinse and repeat.....In about 10 years you'll have a perfected, better, 10 years behind-the-times seed that grow 1500lbers consistently....when our random selections are doing 2000lbs in Henniker, Tenino, and Canada.
(clones rule)

1/19/2005 8:27:20 AM

Cologne / Germany

What about that?

1.) 842 Eaton = 846 Calais x 723 Bobier
2.) 1301 Eaton = 842 Eaton x 1236 Eaton (reverse of 842)
3.) 1446 Eaton = 842 Eaton x 1301 Eaton

Take a good (proven) seed, cross it with the (proven) reverse version of that seed, cross the good seed again with the (proven) result of that reverse cross. Sounds like setting the benchmark for backcrossing. At least it worked for Al Eaton.

1/19/2005 9:10:29 AM

Syracuse, NY

hmmmmmm....i'm gonna print this page out for sure!
anybody out there actually doing crosses and getting actual
fruit from keeping plants alive all winter?
rather than "just" keeping clones alive?
(i mean, that IS a feat!)
imagine that we could double the speed at which our crosses are being made...hmmmm........probably some of us have already completed most of floh's equation, there.....eric

1/19/2005 3:48:47 PM

Syracuse, NY

i guess i'm just a little lost on that equation--maybe we won't know if it "worked" for Al Eaton or not until it gets planted a few times (1446). gotta do work or would research a little! eric

1/19/2005 3:55:50 PM

Cologne / Germany

My equation was more related to what kind of crosses Al Eaton choosed BEFORE he was able to grow a 1446.
We still have too little knowledge what these recent 1400+ seeds can do or will do in the future.
So I talked about an approach what is possible with known proven seeds to come to this point near the magic 1500 mark where we stand today.
I bet we´ll see a 1500 in 2005 basing on the same proven crosses we already know.

1/20/2005 8:10:54 AM

Joliet, IL

i was concerned with crossing the 1446 with the 842 as maybe
too much inbreeding. my first thought was why not take the
world record-thick-walled-over-the-charts pumpkin and self
it. then i thought, well i am not sure how the 1446 will
actually produce because it hasn't been grown yet,
so why not take the proven parent and cross it back into
its kick ass baby. then i began confusing myself with
human genetics and the possibility of mutations from
too much inbreeding. so i went to the expert himself and
Al said it is a sound crossing technique and my mind
was made up to give it a try if both seeds germinate
and are healthy.

1/20/2005 8:10:38 PM

Syracuse, NY

love your weigh of thinking, Shazzy!!!
you can make whatever cross(es) you want, since
most of the time it is a good idea to have at least one
"shock-absorber" fruit on the plant until it's been on there long enough...which i have never determined as to when too long actually occurs. perhaps, the last day of
August? anyway, you can make the cross 1446 X 842, right?
i gather that is the one you want the most, and also
the kickass baby cross, lol, 1446 X 1446, as a shock absorber until it is big enough to have mature seeds from.
i'll take a few, 'kay? my address is......

1/24/2005 7:27:44 PM