Corn and Inbreeding Depression: Want to Start Growing and Saving Seed

Hello all,

Was reading this thread and heard about inbreeding depression for the first time. What I am wondering is how does one go about starting a sustainable corn growing and seed saving project? I can buy several thousand seeds from any number of online stores, but there does not seem to be any guarantee about the genetic diversity of those seeds. A small packet of a few hundred seeds might all come from a single plant. And if they are not willing to even mention the genetic diversity/inbreeding depression factor, I have my doubt that they would go out of their way to provide a diverse batch of seeds to their customers.

Any help and advice on how to get into the growing and saving of some open pollinated heritage corn would be greatly appreciated.

I am fond of saying that there is more diversity in a single ear of any of my corns than there is in a hundred acre field of industrialized corn.

My strategy for avoiding inbreeding depression in corn, is:

All of my varieties started by combining hundreds of varieties into a single strain.
I plant hundreds to tens of thousands of seeds for each variety.
I plant a bit of older seed along with the newer seed.
I allow a bit of pollen drift between similar varieties.
I swap seeds of similar varieties with my collaborators and plant them together.

Jon Wisnoski wrote:Hello all,

Was reading this thread and heard about inbreeding depression for the first time. What I am wondering is how does one go about starting a sustainable corn growing and seed saving project? I can buy several thousand seeds from any number of online stores, but there does not seem to be any guarantee about the genetic diversity of those seeds. A small packet of a few hundred seeds might all come from a single plant. And if they are not willing to even mention the genetic diversity/inbreeding depression factor, I have my doubt that they would go out of their way to provide a diverse batch of seeds to their customers.

Any help and advice on how to get into the growing and saving of some open pollinated heritage corn would be greatly appreciated.

You could do what I did, for exactly the same reason. Just get some seeds from Joseph and start there.

Some great ideas there. But the step I am really stuck at is how to start. Assuming I wanted to shell out $100-$150 for a couple pounds of corn, which is quite an investment for me, from what I am seeing I would not even be guaranteed to have any amount of genetic diversity at all (a 5 lb packet could literally just be 3-5 ears of corn). And no matter what methods I took after that, baring buying in more seed year after year, the corn would be unsustainable. Do you need to search for specific places to buy seed to get the required genetic diversity or do all those online shops that sell seeds mix up their seed corn such that if you bought 5 lbs you would be guaranteed to get seeds from over 200 plants?

Nevermind the descriptor of "Marxist geneticist" in the following---Lewontin was a first rate geneticist in his own right and was not afraid to voice his opinion of hybrid crop breeding, the following link providing a good example with reference to corn:

http://libcom.org/library/political-economy-hybrid-corn

I'm not sure I would worry too much about inbreeding depression in corn with an open-pollinated seed accession. Just keep selecting for traits that you like along with keeping a few off-types just to maintain some extra diversity and you should be okay. Since corn is a natural out-crosser, inbreeding depression is less of a worry than in some other inbreeding crops. If you want to make sure you are not losing yield, you will have to track annual average yields and see if you are giving up any over time. For ~20 years now just using 'Golden Bantam' OP and have not had cause to worry about yield penalty or reduced vigor.

I like this place for heirloom maize seed: http://www.victoryseeds.com/corn.html

Jon Wisnoski wrote:Some great ideas there. But the step I am really stuck at is how to start.

Have you checked out the links in Joseph's signature? He has some *very* diverse genetics in his seeds!

Be certain to save seeds from a large number of plants.
Each of my sources on this recommend a MINIMUM of seeds from 100 plants for corn.

Jon Wisnoski wrote:Some great ideas there. But the step I am really stuck at is how to start. Assuming I wanted to shell out $100-$150 for a couple pounds of corn, which is quite an investment for me, from what I am seeing I would not even be guaranteed to have any amount of genetic diversity at all (a 5 lb packet could literally just be 3-5 ears of corn). And no matter what methods I took after that, baring buying in more seed year after year, the corn would be unsustainable. Do you need to search for specific places to buy seed to get the required genetic diversity or do all those online shops that sell seeds mix up their seed corn such that if you bought 5 lbs you would be guaranteed to get seeds from over 200 plants?

As I said, if you get a packet of 100 corn seeds from Joseph, they have the combined genetics of thousands of different varieties of corn. It will cost you one dime for each packet.

Todd Parr wrote:You could do what I did, for exactly the same reason. Just get some seeds from Joseph and start there.

Burra Maluca wrote:Have you checked out the links in Joseph's signature? He has some *very* diverse genetics in his seeds!

Thanks, I just noticed the link. But he does not ship outside of the US, and his location is so radically different than mine that it might not make a lot of sense. If his corn is adapted to a desert up in the mountains with lots of sunlight than my muddy cold northern climate might be be the exact opposite of what the corn likes.

Jon: How large of a population are you able to grow?

On my very tiny farm, I harvest corn by hand. I harvest the cobs into bushel or half-bushel baskets. Then I shell it into plastic bins. I work in lot sizes representing about 250 to 500 mother cobs, and 5000 potential pollen donors. The seed gets thoroughly mixed up during shelling and cleaning. If you get corn seed from any company that is in the business of selling seed, they are going to be working with lot sizes that are much bigger than that. If you get seed from individuals, you might get different results. For example, a few years ago Glass Gem corn went viral and was a very hot item... I watched as people bought single cobs of it, and turned around and resold them in 10 seed lots on eBay.

I also offer corn seeds from single cobs, but for purposes of plant breeding. The genetic diversity in my single cob offerings is larger than what could be found in a 5 pound bag of industrialized corn. Because I am purposefully aiming for high diversity, and they are aiming for their seed to be as close to clones as it's possible to get.

Internet wisdom suggests that for long-term seed saving, corn should be planted in patches of more than 200 plants, and that seeds should be saved from not less than 100 plants. So how do we achieve that in small gardens? There is the actual population, and then there is the effective population.... For example, if I am only able to grow 100 plants, and only able to save seeds from 50 plants, then what if my sister is also growing corn, and she does the same thing in her garden, and we swap seeds each fall, and we each plant half our seed, and half from the sibling. The effective population has doubled... And now we are at the magic number of 100 mothers. Or what if I grew a population of 100 plants three years ago, and a population of 100 plants two years ago, and a population of 100 plants last year, but when I plant the crop, I'm planting equal proportions of seed from each year. My effective population size is 300 plants. What if 20% of my planting each year comes from a seed packet from a farmer that is growing 10,000 corn plants. Or what if I get some of my seed from a community seed library each year? Those increase the effective population.

The thing about corn, is that if you are willing to give up on the corn looking like it came out of a clone factory, then the risk of inbreeding depression is drastically lowered. The risk with inbreeding depression is that yields will be lower. However, it's simple as can be to add some diversity back into a local variety, by planting a foreign variety into the patch...

I have lots of room. Was planning on doing something in the range of 1/5 of an ache (think the area is 300' by 30'), which should be about 6,000 plants (if the answer Google just spit out is applicable to me). So I should have no trouble after I get started, I just need to figure out what is the best strain to start with.

Jon Wisnoski wrote: 1/5 of an ache (think the area is 300' by 30'), which should be about 6,000 plants

Sounds to me like your are fine with whatever you start with...

Sorry, this made me laugh:

(Joseph's) location is so radically different than mine that it might not make a lot of sense. If his corn is adapted to a desert up in the mountains with lots of sunlight than my muddy cold northern climate might be be the exact opposite of what the corn likes.

I see you're pretty new to permies.com, so please forgive my giggle. Joseph's conditions for growing corn are so poor, that if corn will grow at his place, it will grow anywhere. The other benefit of his seed, is that it has a huge genetic diversity. Some of that diversity will thrive where you are.

Alas, I know the pains of trying to get things shipped north of The 49th, so I've spent a lot of time dreaming about how I would go about growing awesome, genetically diverse corn. This is what I would probably do:

1. Get a library card. read Breed Your Own Vegetables by Deppe and anything else by her they have at the library. The resilient gardener is another good one, with a lot of incredible stuff about corn growing and breeding... actually, that might be the book to start with.

2. Get some corn seed. I don't have much space to dedicate to growing a crop that probably won't do well, so I would probably start with about 25 plants. I would start with five different varieties, and about 5 plants of each. I don't see inbreeding depression being an issue at this stage because the plants would be very different and the offspring mostly hybrids. I have a plan for avoiding future inbreeding depression.

I would get my corn from Salt Spring Seeds because I know they are awesome, heritage harvest seed because I've had success with them in the past, and if I couldn't get Josephs, then I would probably get some from Baker Creek seed. Thier clime is pretty different than mine, so the success rate is hit and miss, but even if their plants failed to produce seed, they still contribute pollen.

5 packets, at say $5 each, that's 25 dollars. Not horribly expensive.

If I grew the corn in little clusters (like the First Nations did), then I would plant one or two of each variety in each cluster, to improve cross pollination.

3. Save seeds from everything the first year. Just let nature do the selecting, she's good at it. Whenever you choose to save seeds from one plant and not another, then you are also doing the selecting.

4. 2 year planting - plant some from last year and some from the year before, and add new genetics as you like.

Basically, I would take half my seed from year 1, put it in the freezer for long term storage. Plant 1/4 of the seed, plus maybe half of what's left from the seed packets. I might be tempted to add another variety or two if I see something smashingly good in a seed catalogue.

I don't know if I would want to do any selecting this year, as mother nature will be doing a fair bit in my growing conditions. But I might cull those that are slow to germinate.

5. 3rd year, there should be lots of genetics by now. I would probably do some selecting to choose the traits I want most.

3 years, $30, not too bad for a new variety of corn.

Thanks for the continued advice. I was unaware of how easy and advisable it was to interbreed just about anything you want all the time. I would of thought that the results would of been so unpredictable that maintaining the pure genetics would be important.

Also, there has been a further development. Just heard that Victor Kucyk (http://threedaughtersfarm.com/wp/?p=1106
) lives like an hour away from me. And his corn sounds pretty close to ideal. Looking into that avenue as we speak.

One of my sweet corn varieties is descended from over 200 varieties of sweet corn, including every heirloom we could get our hands on, and many modern varieties. The varieties originated in southern areas from Baja California through Florida, and northwards to North Dakota and New York, and everywhere in between.

Another of my sweet corn varieties is descended from that variety plus hundreds of accessions of native corn varieties that were collected from the Caribbean, the Brazilian rain-forests, the Andes, and everywhere in between.

That doesn't mean that my corn grows great everywhere. It grew really poorly in Malaysia for example... But it grew really well in Belize. But for someone developing their own variety of corn, there is tremendous genetic diversity, and something is likely to produce seed wherever it is planted. Then its just a matter of selecting for one's own conditions and habits. I have been most surprised by how well my varieties tend to do in areas with blazing hot summers. Because even though my varieties might not have all that much resistance to mildews, they grow vigorously and fast, and can produce a crop before the worst of the summer heat and humidity arrives and kills the plants.

I've trialed thousands of varieties of vegetables over the years... Buying seeds from a seed company is fraught with peril, because the only thing I have to base my decision on is a photo and a glib description in a seed catalog. I'm better off asking for varietal recommendations from local gardeners that are already growing a crop. On spinach, 50% of varieties failed for me. On watermelons it was closer to 100%. Any turnip that I plant has grown well, though some of them failed for social reasons. The success rate of other varieties varies all over the place. I only expect about 25% of squash varieties that I buy from a seed catalog to work here.

In a 1/4 acre corn patch, I wouldn't worry about inbreeding depression as long as more than 100 mothers were saved for seed whenever seed needed to be refreshed, which might only be 1 year in 5.

Jon Wisnoski wrote:Thanks for the continued advice. I was unaware of how easy and advisable it was to interbreed just about anything you want all the time. I would of thought that the results would of been so unpredictable that maintaining the pure genetics would be important.

I am doing all of my corn growing by hand, so it doesn't matter to me if there are variations in maturity dates, or if the cobs are slightly different sizes, or if the colors or shape change from cob to cob, or if the cob placement varies between 3 and 6 feet from the ground. Uniformity matters to machine scale agriculture, not to human scale gardening.

The grand secret of plant breeding, is that children tend to resemble their parents and grandparent. The fruit doesn't fall far from the tree. So sweet corn doesn't spontaneously turn into popcorn, or field corn, or dent corn. It doesn't spontaneously develop bitter flavors, or start growing like a tomato. If I plant corn that grows to be 6 feet tall in my garden, and plant other corn with it that grows 6 feet tall, then the offspring are going to be six feet tall. The children bear a striking family resemblance to their parents and grandparents. If I plant a 2 foot tall and a 10 foot tall corn and let them cross pollinate, then the grandchildren will be anywhere from 2 to 10 feet tall. But as long as I am planting similar corns together, they will produce similar children and grandchildren.



Note: If SH2 crosses with regular sweet corn, a non-sweet corn can be produced, but that's a special case.

On the topic on interbreeding corn varieties. Is hand pollinating the only method to prevent cross pollination when all your neighbours grow GMO corn? Is hand pollination doable for crops of ~10,000 corn plants, without spending exorbitant amounts of time and or money on it?

Jon Wisnoski wrote:Is hand pollination doable for crops of ~10,000 corn plants, without spending exorbitant amounts of time and or money on it?

10,000 corn seeds can be produced by about 40 cobs of corn. So the limiting factor on hand pollination seems to be the number of plants needed to maintain a genetically viable population. Shall we say 200 plants? 100 to be mothers, and 100 different plants to be pollen donors.

The method would be to put paper bags over the tassels and staple them together to prevent contamination. And also putting bags over the silks to prevent contamination. Then collect the pollen, and dump it over the silks. My method of hand pollination is to collect pollen into a black plastic tub by shaking the tassel over the tub, and then use my fingers to smear pollen on the silks. I collect pollen from the whole patch before doing the pollinations...

Supposing that it takes 7 seconds per plant to install the bags, and then 7 seconds per plant to collect the pollen and do the pollinations. 14 X 200 = about 1 hour.

Oh, so you are saying that I only need to hand pollinate the ones I end up keeping seed from. That's a way better idea than hand pollinating every single plant.
But that would sort of prevent me from picking for the best traits? Or at least extremely limit my ability to, as I make most of the choice well before it is particularly obvious how well a plant will produce.

Jon Wisnoski wrote:Oh, so you are saying that I only need to hand pollinate the ones I end up keeping seed from. That's a way better idea than hand pollinating every single plant.
But that would sort of prevent me from picking for the best traits? Or at least extremely limit my ability to, as I make most of the choice well before it is particularly obvious how well a plant will produce.

By the time a corn plant is silking and tasseling, the mold is pretty much set. You can observe how tall it is. How vigorously it grew. Whether it is particularly susceptible to bugs, diseases, or lodging. So you choose the best plants as the mothers and fathers. If you double your effort at pollination, then you could cull half of the pollinated cobs, and still have enough left over for a genetically viable population.

Jon Wisnoski wrote:On the topic on interbreeding corn varieties. Is hand pollinating the only method to prevent cross pollination when all your neighbours grow GMO corn?

Other methods would be to choose varieties and planting times, so that your corn flowers at a different time than your neighbor's corn...

If you are growing sweet corn only, and they are growing field corn only, then you would be able to visually observe the cross pollinated seeds, and they could be culled before replanting.

How about some sort of physical barrier like a hedgerow or growing a tall crop around the corn? Mongolian giant sunflowers grow about 12 foot high, I imagine they would do the trick. I had one grow over 20 foot last year.

I don't know if this would totally reduce the chance of foreign pollen coming in, but it would help, wouldn't it?

Also, how about growing a colourful corn? My limited knowledge about corn is that you can sometimes see when sorting the seeds which corn is 'infected' with foreign pollen.

Also, by planting large patches, and only saving seeds from the center of the patch, the sheer magnitude of the local pollen produced can dramatically out-number pollen blowing in on the wind. Pollination is a highly localized event to start with. For example, corn pollen falls at 0.8 feet per second, so it only travels about 25 feet in a ten mile per hour wind before falling below silk level. In my fields, where I hardly have any wind during the summer, a corn plant pretty much only pollinates itself and the neighbors within about 18 inches.

Here's a photo that demonstrates what I mean... I inadvertently planted a cob of purple corn inside a patch of white corn... The lower cob grew 3 feet from the colored corn, and it got a little bit of pollen from it, less than 5% crossing even at that close planting distance.

I recently bought some 'Hopi blue' seeds and planted out a patch of 24 plants in my back garden. I found two very rare mutants amongst my harvest - one tassel ear, and one ear with a tassel growing out of it.

Tassel ears are a rare occurrence where a cob of corn develops on the normally male tassel. According to Purdue (and if anyone knows something about corn oddities, it's them), it is exceptionally rare for tassel ears to form on the main tiller, more usually occurring on side shoots.

The second condition, a tassel forming on the end of an ear of corn, was not in the list of corn-related oddities of any of the American land grant universities. The tiller even has a bit of tiller ear itself, with a few kernels on the tiller.

A number of heirloom corn varieties, and 'Hopi blue' in particular, were brought to New Zealand in the 1990's to protect them from cross-pollinating with GMOs (which has since that time taken many traditional varieties off the market in the US), so that someday these varieties could return to the US and the local and indigenous communities that developed and maintained them. They have been preserved by home gardeners and small seed companies in New Zealand for the last thirty or so years. To have two incredibly rare mutations like this in the same population (of <30) leads me to suspect that there is some inbreeding depression in the seeds I sourced. Has anyone else run across these mutations? I want to help look after these seeds and preserve them for future generations.