Landrace

[DarJones]

Which brings on the topic of genetic drift. This is what happens when you grow a diverse crop under specific conditions for several years and cherry pick the best offspring to produce the next generation. Over time, the crop will become adapted to the set of conditions under which it is grown and by default will lose genes that are defective in that environment. This can include genes that could be advantageous in different conditions. As an example, if you take an open pollinated corn variety that is adapted to growing in Michigan and grow it in Alabama for several years, the variety will drift toward a better producing variety for Alabama's long hot humid growing season.

DarJones

[Alan]

Fusionpower and Blue bring up very good points. My experience has been much like Josephs, it's amazing to plant a field of a couple hundred varieties of watermelons and instantaniously (upon germination) see exactly what already has the makings of a good contributor to the genepool.

I am presuming that Joseph, like myself, also keeps on hand old seed stock from different years past, in case of disaster, I also usually tend to add some of these seeds back to my planting mix on a yearly basis just to make sure I'm at least holding onto as many genetic possibilities as I can, but in time, as stated above, we will loose a great deal of diversity, but I think to really take this down to the bare bones of a locally adapted variety would take a couple generations of my family or others growing out this seed stock and making hard selections by way of nature or man over many years.

[canadamike]

This is where taking a genepool and developiung it in many environments become interesting. By growing from the same starting point in diffferent climate and helping each other, we can later re-introduce genepool that originated from the same trunk but ''learned'' to behave differently.

Each of our Astronomy Domine ''strains'' will exhibit difference but by making them available to others we can, in a way, re-acces the original genepool material that is well adapted to ''such and such'' very different conditions.

I feel that my english is blurry tonight

[Alan]

Michael, I need your addy and phone number buddy. I have seeds and ideas for you.

[Joseph Lofthouse]

Jan 17, 2011 19:46:11 GMT -5 Alan said:

I am presuming that Joseph, like myself, also keeps on hand old seed stock from different years past, in case of disaster, I also usually tend to add some of these seeds back to my planting mix on a yearly basis just to make sure I'm at least holding onto as many genetic possibilities as I can

I also plant older seeds each year, so that one unusual growing year doesn't seriously mess up the gene-pool.

On my most important breeding programs I like to plant in multiple fields in different water-sheds, so that if one irrigation system fails (most likely due to flood, mudslide, or earthquake, or social upheavals like divorce or foreclosure) a different system might survive.

I seal seeds from my breeding programs into #10 steel cans (3 quarts), and distribute them to friends and family just in case I lose my main seed stock, and the backup I keep at home.

This spring my father is intending to plant the contents of one of those cans after many years. We'll see how it goes.

[eightfoldfarmer]

Hi Everyone, I'm new to the forum as a member, but have found myself returning here (lurking) for information and inspiration since I stumbled upon Homegrown Goodness nearly a year ago.

I just found a great pdf tome on European Landraces.
[a href="http://www.bioversityinternational.org/index.php?id=19&user_bioversitypublications_pi1[showUid]=3252"]http://www.bioversityinternational.org/index.php?id=19&user_bioversitypublications_pi1[showUid]=3252[/a]

I've just started skimming it but I ran into this definition:

“A landrace of a seed-propagated crop is a variable population,
which is identifiable and usually has a local name. It lacks 'formal'
crop improvement, is characterized by a specific adaptation to the
environmental conditions of the area of cultivation (tolerant to the
biotic and abiotic stresses of that area) and is closely associated with
the uses, knowledge, habits, dialects, and celebrations of the people
who developed and continue to grow it.”

Cheers,
Eric

[aineo]

I have read through this thread and others, and one question keeps coming up. If multiple types of squash are used to produce a landrace, isn't that landrace a hybrid? Hybrids, of course, have a bad name with seed savers, but from what I have read on this forum, landraces are a very positive thing.

Just to ensure I understand: if I am attempting to landrace tomatoes (and yes, I know this isn't the best example due to inbreeding) and I like the taste of the Cherokee Purple, the way the Super Sioux handles hot, dry summers, and the coloring of the Chocolate Stripe, then I would plant all three, saving the seeds of the ones that best fit my desires. I then replant the seeds, perhaps along with more of the parents or other varieties, and do the same all over. After a number of seasons, I should theoretically have a tomato well suited to my climate, and exhibiting the traits I am looking for. I assume that there comes a point you have a stable variety that would consistently produce given no new varieties are introduced.

I feel a bit dense on this, but I am trying to get my head around this.

[oxbowfarm]

Hybrids are often vilified in the heirloom gardening circles. There are some good reasons for this, as they have resulted in fewer people saving their own seeds. Possibly contributing to the loss of diversity in many crop species. But that is more of a social/societal problem inherent to human beings. It is useful to keep in mind that the terms "variety", "heirloom", and even "species" are mental constructs we use to help us understand plants on some level. To the plants themselves those terms are irrelevant. The difference between a "hybrid" squash and an "heirloom" squash are only relevant if they differ in phenotype characteristics that personally matter to you in your garden. The idea that HYBRID = BAD, HEIRLOOM = GOOD is a silly oversimplification that thankfully doesn't crop up much here on HG.

Landraces may or may not have "hybrid" individuals in the population. It usually depends upon the breeding system of the particular plant. Outbreeding plants in a landrace are going to be trading a lot of genes around and you'll have a lot of individuals that have high levels of heterosis. Inbreeding plants would tend be more composed of mostly homozygous individuals with possibly the occasional cross going on. And a whole spectrum of in-between situations that might vary based on climate and ecosystem factors (humidity, pollinators, lattitude, etc) A dry bean landrace grown in my climate would probably show very little crossing between the different bean types in the mix. Grown somewhere else where the climate and ecosystem are different (like the Willamette Valley according to Carol Deppe) and you would see a lot of crossing.

[Joseph Lofthouse]

Aineo: That's correct. A landrace of out-breeders has a lot of hybrids running around in it. That is part of why landraces are so successful: They have a lot of hybrid vigor.

A landrace of in-breeders is slower to adapt, because the cross pollination rate of tomatoes might be around 5% in an average garden, so it takes a lot of years, or a lot of plants to discover the crosses and select for them. But once you get a cross, the genes in the offspring continue to reorganize themselves for years. Hand pollination to cross the in-breeders can really help with landrace development. Over the years, if you select for the obvious natural hybrids, you will tend to be selecting for plants with a higher cross pollination rate.

I like starting my landraces with hybrids. The F2 generation provides lots of diversity to select from. A problem with some hybrids is that the hybrid seed for many species is made with mothers containing cytoplasmic male sterility, which is transmitted by the mother, so the line will always be male sterile. I don't like that in my garden, so I avoid using hybrids for those species: Carrots, onions, potatoes, beets. Some species are still OK even if hybridized: Squash, tomatoes, beans, peas, spinach. It's too hard to tell with the brassicas, because their hybrids can be made either with self incompatibility or with male sterility, so I avoid including brassica hybrids in a landrace.

When I first became aware of cytoplasmic male sterility, I discovered that about 70% of my carrot crop was male sterile. Functionally, the plants were still reproducing, with the 30% of the pollen bearing plants doing all of the pollination. And there was lots of hybrid vigor going on. I just didn't like the thought of having so many plants that were only partially functional. But I grow a garlic landrace with 100% sterile plants. That has worked out fine for me so far.

In the broadest sense of the word, landraces are always stable varieties, because a tomato always produces a tomato, and a squash always produces a squash, etc...

At any time, you can pull one plant out of a landrace, and start inbreeding in order to turn it into a standard stabilized cultivar. I haven't chosen to do that with any of my landraces, but it could be done.

I tend to group my landraces by phenotype based on how I use them: So I'll have a landrace for cherry tomatoes, and a landrace for canning tomatoes, but I don't really care about the shape or color of the fruits. With one type of my landrace sweet corn, I keep the days to maturity consistent at about 73 days, and let other traits vary widely.

[keen101 (Biolumo / Andrew B.)]

There are several threads with the subject of "landraces", "Grexes", arguments about landrace breeding etc that i could have posted this in, but i chose this one since it had an unbiased title. Plus it's a thread Alan has talked in, so thats always nice.

Recently i encountered the term "evolutionary breeding". It seems you can find quite a bit when googling that phrase vs "landrace"

www.agriculturesnetwork.org/magazines/global/cultivating-diversity/plant-breeding

[Joseph Lofthouse]

It was nice to see a paper in 'Frontiers in Plant Science', which suggests adopting the definition of landrace which I have been advocating since 2009.

Front Plant Sci. 2017; 8: 145.

... we propose a more inclusive definition of landraces, namely that they consist of cultivated varieties that have evolved and may continue evolving, using conventional or modern breeding techniques, in traditional or new agricultural environments within a defined ecogeographical area and under the influence of the local human culture. This includes adaptation of landraces to new management systems and the unconscious or conscious selection made by farmers or breeders using available technology.

[steev]

That sounds like it could give Big Ag paws.

[Joseph Lofthouse]

Nov 19, 2017 20:37:55 GMT -5 steev said:

That sounds like it could give Big Ag paws.

I know... I didn't want to say that out loud: Legitimizing landraces so they can be stolen.

[steev]

Those dogs!

[walt]

Jan 13, 2013 20:03:33 GMT -5 Joseph Lofthouse said:

....A landrace of in-breeders is slower to adapt, because the cross pollination rate of tomatoes might be around 5% in an average garden, so it takes a lot of years, or a lot of plants to discover the crosses and select for them. But once you get a cross, the genes in the offspring continue to reorganize themselves for years. Hand pollination to cross the in-breeders can really help with landrace development. Over the years, if you select for the obvious natural hybrids, you will tend to be selecting for plants with a higher cross pollination rate..........

Most of the published work on landraces was done with barley, a mostly selfing species.  Dr Harlin and Martini, his assistant made many populations, some with only 2 parents, others with as many as 16 parents.  
They hand pollinated enough plants to get a good F2, in the case of 2 parent populations.  The 16 parent populations they tried two ways.  Mixing equal amounts of F1 seeds from all possible crosses of the 16 parents, and crossing them in pairs, then crossing those F1 hybrids in pairs, then those resulting hybrids, and so on.  In each generation they made enough crosses of each pair to not lose genetic diversity of any hybrid.
When the final crosses were made to start a given population, they just grew that population every year for 25 or more years.  Typical results were about 5% increase in yield in each generation.
Most of this work was done in Arizona, though several of the populations were split and one sub-population was grown every year in Arizona, the other in Bozman, Montata.  I was suprised to learn that Those selected in Arizona did quite well in Montana and the reverse too.
Samples were put into long-term storage, some populations were sampled every generation, others every 5 years.
 Years later, Allard studied the samples.  He found that genes for imunity to diseases tended to be selected against by natural selection, even when the disease was  presant.  He studied many other gene frequency changes in these populations.
I have read that when Dr. Harlan was being introduced before he gave a speech, the introducer said D. Harlan would always be remembered for being the first barley breeder to use replicated trial in barley breeding.  Then Dr. Harlan started out by saying he wasn't proud of being the first barley breeder to use replicated trials.  He was proud to be the first to QUIT using replicated trials.
If a big enough populaton can be grow every generation, inbreeders will respond to just as good as outbreeders.
This refers to Dr. Harold Harlin, not Dr Jack Harlin, who is also justifiably famous.
CIMMYT also did massive long-term breeding in the same way with triticale, wheat, and barley.  All more or less inbreeders.