RE: Hybrid Vigor
Brian...we already do that. The fruit will only grow large if it survives.
Seed genetics that show a tendency to split, even at large sizes, are
usually cast aside for better genetics. This does not mean that if one
fruit splits, no one ever grows that seed again. It just means that people
are more discerning in their selection of that fruit for it's other traits.
There are also many of us interested in fruit color, shape, skin texture,
etc. I personally will not grow a seed that produces ugly fruit. (I know,
I know, eyes of the beholder and all that...) Others don't like to grow
long fruit, still others watch out for fruit with stem or vine problems.
That is what makes this hobby unique and interesting. We are not breeding
for the perfect fruit, because each of us has a different idea of what the
perfect fruit is. (Although many of us who saw it would agree that the
Calai 845 was pretty darn close.)
-Gus
-----Original Message-----
From: Brian Reid [b*@charter.net]
Sent: Monday, December 22, 2003 7:40 PM
To: pumpkins@hort.net
Subject: Re: Hybrid Vigor
I guess the percentage of seeds that could be considered to have the
specific
trait could be more......but it could also be less. It all depends on what
trait
you're trying to isolate. If, for example, you're looking to isolate the
genes
that allow a plant to deal well with heat stress, the percentage of the
plants
that will demonstrate that specific trait may be only a very small fraction
of the
total seed count. That's not to say the genes aren't necessarily present in
the
other seeds, it just may be that they're recessive and don't regularly
surface.....which is where my 30% came from. I guess it really depends on
what it
is you're trying to accomplish and how often the trait you're after
surfaces.
Obviously, we all want a seed that will throw a big heavy pumpkin. Sounds
easy
enough to isolate the genes that would allow us to do this. The part that
gets me
is all the other genetic traits that are required to get the pumpkin to keep
growing and remain intact until the weighoff. I bet any one of you
experienced
growers out there can get a pumpkin to grow at 30+ pounds a day with enough
fertilizer...but it would split like nobody's business and would never make
it to
the end of the season. I think that skin elasticity, rot resistance, steady
growth
rate, vine structure, disease resistance, etc. are just as important as the
gene
that contains the potential to grow to 1500+ pounds.
Great discussion guys. I enjoy learning from the experienced growers! Please
feel
free to comment on my post. It's just off the top of my rookie head so I'm
interested in your comments.
Happy Holidays
Brian
Cliff Warren wrote:
> Brian, all:
>
> I think you summed up the math part of what I was trying to say... 15, or
> maybe
> 12 for our purposes, seeds from the same GOOD seed stock, planted under
> nearly identical conditions and self-ed or sibbed.... Then keep only those
> seeds
> from one resulting fruit that has the characteristic you want (weight)...
> This could
> lead to a superior seed stock, especially if it were repeated for several
> years.
>
> What seed to start with? Any good seed stock that has characteristics you
> like
> would do. But you'd have to like it... because you'd be stuck with it for
a
> long time.
>
> We could get too technical on the numbers... (OK, I'm too lazy or busy to
do
> more
> math! ;-) ) But I would apply some fuzzy logic here and say:
>
> Fifteen plants would make a superb experiment. I think Brian's numbers
show
> that.
> Although, I think all or most of the seeds, not just 30%, would be
> applicable on a
> good seed stock.
>
> Twelve plants would probably make a good experiment.
>
> OK, if I get bored tonight (doubtful) I may try to figure out some
numbers.
> ;-) I'm
> getting rusty on this stuff.
>
> Me? I have a wife and 5 kids and a full-time job, so I have no time for
> pumpkins.
> But I make time anyway and try to grow 3 or 4 plants. ha ha
>
> Regards, Cliff
>
> >From: Brian Reid <brianreid@charter.net>
> >Reply-To: pumpkins@hort.net
> >To: pumpkins@hort.net
> >Subject: Re: Hybrid Vigor
> >Date: Mon, 22 Dec 2003 14:38:05 -0800
> >
> >Cliff,
> >
> >The math is the easy part. When all the talk about genetics, lineage,
> >crossing
> >back, hybrid vigor, etc. starts I'm at a loss. I have no clue when it
comes
> >to
> >seed genetics, and I've been unable to find any site out there that helps
> >me with
> >the genetics part of it. Thank you guys for posting on here and giving me
a
> >lesson
> >on the basics....and the not so basic. Keep up the great discussion and
> >I'll
> >continue to try and take it all in.
> >
> >Happy Holidays
> >
> >Brian
> >
> >clarion wrote:
> >
> > > Brian and Cliff;
> > >
> > > Great postings from both of you guys! You guys do the math and just
tell
> >us
> > > dummies what the hell will work to do a properly controlled experiment
> >and get
> > > accurate results!
> > >
> > > Marc
> > >
> > >
>
>---------------------------------------------------------------------------
--
> > > ---
> > >
> > > I'm a newbie and don't know a lot about seed genetics but I do know a
> >bit
> > > about
> > > statistics. You are pretty close with your estimation on the number of
> >seeds
> > > you
> > > need to grow Cliff. Obviously, we're making a couple of assumptions
when
> > > saying
> > > you only need to grow 15 seeds to obtain a 95 percent confidence
> >interval.
> > > The
> > > first and biggest assumption is the percentage of seeds in the pumpkin
> >that
> > > possess the traits you're after. Without acutally growing every last
> >seed,
> > > it's
> > > a shot in the dark. Half of the seeds in the pumpkin could contain the
> >traits
> > > you're after or as little as 10 percent of the seeds could contain the
> >trait
> > > you
> > > want. This assumption greatly effects the number of seeds you need to
> >plant
> > > in
> > > order to get an accurate representation of all the seeds. The second
> > > assumption
> > > is that the data is accurately represented by a normal curve. I ran
the
> > > numbers
> > > and used a probability of 0.3 or 30%....meaning that we're assuming 30
> > > percent
> > > of the seeds in the pumpkin will exhibit the trait you're after. I'd
say
> > > that's
> > > a pretty fair and conservative estimate. The higher the probability,
the
> >less
> > > seeds you have to grow.
> > >
> > > To figure out the number of seeds you need to plant in order to
> >establish a
> > > 95
> > > percent confidence interval, you have to first find the standard
> >deviation.
> > > Sorry if no one wants to see how the numbers work out, but I think
it's
> > > important.
> > >
> > > std. dev. = [np(1-p)]^1/2 where n = the total number of seeds and p is
> >the
> > > percentage of seeds that posses the trait you want.
> > >
> > > = [(300)(0.3)(1-0.3)]^1/2 = 7.94
> > >
> > > Using the std. dev. of all the seeds we just found you can calculate
the
> >std
> > > dev. for the based on only 15 samples. This calculation will give us a
> >number
> > > that represents how confident we are that the 15 seeds we planted
> >accurately
> > > represent the 300 seeds in the pumpkin.
> > >
> > > For 15 seeds.....
> > >
> > > std. dev. for the sample = (std. dev. of the 300 seeds)/(n^1/2)
> > >
> > > = 7.94/(15^1/2) = 2.05
> > >
> > > So, using 15 seeds we've covered a little more than 2 standard
> >deviations.
> > > This
> > > means that by planting only 15 seeds of the 300, we're representing
the
> >300
> > > seeds with an accuracy of 95 percent. By planting only 15 seeds,
you're
> >still
> > > getting a fairly accurate representation of all the seeds (95%
accuracy
> >to be
> > > exact) but you're doing a whole lot less work compared to planting
every
> >last
> > > seed in the pumpkin.
> > >
> > > Brian
> > >
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