Fertile seeds from seedless watermelons

So, I'll be honest, I prefer the flavor of watermelons with seeds over seedless watermelons.  To me seedless watermelons, while still good, are weak flavored/watered down.  That said, my family gets them from time to time, and in each one, I've found 1-5 normal looking black/dark brown seeds.  So, out of curiosity, I have saved the seeds from about 5 melons thus far, and will continue to save them as the summer wears on for a possible future planting experiment.  I've done some research into how seedless melons are made, and I'm not going to go that route with these.  My plan is to simply treat them like any other watermelon seed with the hope that they'll produce seeded fruit.  I know there are 2-3 different varieties in this mix, which I'll let pollinate together.

Has anyone out there tried this, or have any info I might be missing?  Thanks.

So, seedless watermelons are a result of artificial hybridization. They're basically the 'mule' of the fruit world.

Mules are the offspring of a male donkey and female horse. They are 99% sterile, sturdier than a horse, and smarter than a donkey.
A horse has 64 chromosomes. A donkey has 62. Both are diploid. Two sets of matching chromosomes - a pair. During Meiosis, the two chromosomes in a pair need to look very similar to properly match up, pull apart, and be replicated.
Mules end up with a fairly random mix of 63 chromosomes. So not only do donkeys have an un-even number of chromosomes, the 'pairs' dont necessarily match up - Pair 1 may be two horse chromosomes, two donkey, or one horse and one donkey chromosome.  
This means it's very very very VERY rare for a mule's own sperm or eggs to be capable of joining to create a viable embryo.

With that established, lets dive into fruit genetics!

Watermelon plants are normally Diploid, like us and like horses. They have two sets of chromosomes. An even number.  

Seedless watermelons are Triploid - they have three sets of chromosomes. This odd number results in them being sterile and not producing viable seeds. You create a triploid watermelon by mating a diploid (2-sets-of-chromosomes) male with a tetraploid (4-sets-of-chromosomes) female.

To get a Tetraploid (4-sets-of-chromosomes), you apply a chemical called 'Colchicine' which interrupts cell division and messes with it. It basically forces the chromosomes to double themselves - going from diploid to tetraploid. You have to cultivate these over several generations to get enough that produce enough viable seeds with suitable traits.

Watermelon plants have male and female flowers. The female flowers have little pea-sized melons behind it.
You have to remove the male flowers on the tetraploid plants, because a diploid female will always produce a diploid-seed fruit. Only the Tetraploid plants can produce Triploid fruit.

Pollen from the male diploid plant's flower goes into the tetraploid's female flower.

And now it's go time.

Seeds from the triploid fruit grow into triploid plants. They don't produce much pollen, so you plant some diploid plants. This pollen stimulates the triploid female flowers to produce fruit.
Because the number of chromosomes is not compatible, the seeds inside this fruit are seeds that will grow into more "Seedless" Triploid watermelon.

Planting seedless triploid watermelon alongside diploid seeded 'pollinator' watermelon will create fruit on the seedless watermelon that contains one of two options:
1. Zero fertile seeds (most common)
2. A few fertile seeds alongside a lot of nonviable ones.
(Plus you'll get normal seeded watermelon from your pollinator, if you let any of them grow)

Where do the fertile seeds come from?
Rarely, and under some circumstances, the Triploid cell can undergo spontanious Meiosis before fertilization, becoming a Hexaploid cell. (6-chromosome pairs). This then gets fertilized and, since it's an even number again, it can successfully pair off and produce fertile seeds.

Thus: the rare viable seeds from seedless watermelon.

In conclusion:

Yes, you can plant the black seeds and get more 'seedless' watermelons.
To continue getting a few viable seeds out of your seedless watermelon, you need to plant normal seeded watermelons alongside it, and make sure some cross-pollination happens.

Producers of 'seedless watermelon' seeds usually have a bunch of Tetraploid and Diploid plants, which they cross-breed and sell the seeds, because the hybrid between Tetraploid and Diploid will be a 'Seeded' watermelon whose seeds grow 'Seedless Watermelon' vines.

Wow, what an excellent response, thank you!  I didn't know about the 'Colchicine' part of the process.  I thought it was the specific high heat at germination that caused the difference.  

So, to reinforce my understanding...

Are these few fertile seeds like the ones you can buy from the seed companies as "seedless" seeds that on the packet instructions, say "plant with a pollinator variety"?

If I plant these fertile seeds from the seedless watermelons next to some "sweeter variety" seeds, the additional pollen from the seeded variety will help the seedless female flowers to produce fruit that will be seedless (with the occasional fertile seed possible)?  Or, will we be back to even number of chromosomes without the 'Colchicine' part of the process, thus creating seeded offspring from then on?

Cy Cobb wrote:Are these few fertile seeds like the ones you can buy from the seed companies as "seedless" seeds that on the packet instructions, say "plant with a pollinator variety"?

The seed packets you buy are almost always a direct hybrid cross of chemically-created Tetraploid and Diploid watermelons.
The melon growing on the tetraploid vine are full of seeds that, when planted, will grow a “seedless watermelon” vine that needs a diploid/regular watermelon to pollinate and bear seedless fruit.

The rare/few fertile seeds that naturally occur in seedless watermelon are due to chance mutations, and are not a stable model of business for seed producing companies.

If I plant these fertile seeds from the seedless watermelons next to some "sweeter variety" seeds, the additional pollen from the seeded variety will help the seedless female flowers to produce fruit that will be seedless (with the occasional fertile seed possible)?

Or, will we be back to even number of chromosomes without the 'Colchicine' part of the process, thus creating seeded offspring from then on?

So you have 6 sets of chromosomes from miss mutant embryo.
And 2 sets from the new pollinator male.

together they were lucky enough to make a seed that got 4 sets, and will form fully seeded Tetraploid watermelon.

Congrats you now have seeds that will grow a full-seed watermelon vine, whose seeds should then produce seedless watermelon vines if you cross them with normal diploid watermelons.

Or it will grow a vine that never flowers, because some hybrids are so sterile that they never develop reproductive organs at all.

You’ve got the seeds

Wanna test your luck?

Ha ha, I do.  Thanks for the insightful clarification. Much appreciated!

Ooh very informative post thread. How'd the melon growing go? I found a single mature seed in a seedless watermelon from the store last year so I planted it and dove into researching how to do it. I cross pollinated it with a sugar baby vine and it produce 14 watermelons over the course of the Hawaii summer and fall, all weighed 14-16 lbs with sweet yellow flesh (I had gotten the seed out of a red flesh melon) and they were full of mature seeds. Towards the end of the season it started produce herm flowers with both male and female parts and a different looking elongated fruit but none of those ever got to ripen. I've got my little melon plants growing now and I've already confirmed last year that these seeds can sprout and flower, after reading through this thread I think it answers the question I had about if I would keep needing to cross pollinate these with a diploid. I can't wait to see what kind of melons the seeds grow, but at least now I know I can expect them to be seedless. I also bought another seedless watermelon 2 weeks after the first one and it had 1 mature seed as well but that one grew what people would call pig melons and was worthless but I saved a few seeds anyways to see what the next generation might look like.

George, here's a quick update of where I'm at in this project.

For the past couple years, I've been buying locally grown seedless watermelon of all varieties, roughly every other week throughout the summer months.  I noticed that these "seedless" watermelons would have anywhere from 0-6 mature seeds within, but in most cases 1-2.  I was curious if they'd grow, and if so, what would I get?  So, I began saving the mature seeds I found, and am probably up to 30 or so now.  

While I was amassing my collection, I decided to try growing commercially available "seedless watermelon" seeds of 2 red-fleshed varieties alongside a few varieties of seeded orange flesh and a few varieties of seeded yellow flesh watermelons, so that I could easily tell them apart once I cut into them.  The idea was that anything with red flesh should be seedless.  This was not the case...for some reason that eludes my understanding, I had seeds in what should've been seedless varieties.  I did grow them in a survival of the fittest scenario in harsh conditions, with loads of pollinators, so perhaps the stress or high pollination changed something.  I don't know.  I do still have enough seedless seed to try a few more times, but it was a head scratcher for me.  

But to get to the point, I've not yet planted those saved seeds from my store-bought seedless watermelons. I think when I do, I'll plant them alongside something different in color and shape such as Charleston Grey so I can easily tell which are known seeded pollinators, and anything else would be from saved seedless seed.  In the mean time, I'll continue saving the seeds this year, and when I do finally grow them out, maybe next year, it'll be one big patch with 3 years' worth of seed.  Not really sure what'll happen, but maybe I'll get some watermelons out of it?  

I am curious though, can you explain "pig melons" to me?  

So pig melons is something I learned about when I was researching plant breeding, apparently iirc some people breed pig melons with other melons so there's a chance of seeds from store bought melons growing pig melons. What they are are basically small melons with white flesh that doesn't get sweet so the plants just get used for breeding aspects and the melons get tossed into pig pins as pig food, I think their bred in for their vigorous growing habits. Btw seedless watermelon varieties usually have a suggested pollinator variety that shares some of the genes if you can figure out what kind you bought from the store you can find the suggested pollinator variety. Gl to you on this, I only had 2 seeds so 50% win rate so far but the fact that it produced 14 watermelons really impressed me as the sugar baby that pollinated them couldn't produce half that.

>>Where do the fertile seeds come from?
Rarely, and under some circumstances, the Triploid cell can undergo spontanious Meiosis before fertilization, becoming a Hexaploid cell. (6-chromosome pairs). This then gets fertilized and, since it's an even number again, it can successfully pair off and produce fertile seeds.<<

Yeah, I don't think that's what happens to produce the occasional viable seed in a seedless watermelon. The would be pollinated by a diploid melon which would only contain 1 set of chromosomes, so that would result in an an odd number of chromosomes again (7). What most likely happens is that occasionally you get 1 set of chromosomes during egg cell meiosis and when pollinated by the diploid male parent (again 1 set of chromosomes as per usual in sexual reproduction) you now have a viable diploid seed.

Welcome to Permies, Rob! Glad to have you here.

Rob Gaines wrote:>>Where do the fertile seeds come from?
Rarely, and under some circumstances, the Triploid cell can undergo spontanious Meiosis before fertilization, becoming a Hexaploid cell. (6-chromosome pairs). This then gets fertilized and, since it's an even number again, it can successfully pair off and produce fertile seeds.<<

Yeah, I don't think that's what happens to produce the occasional viable seed in a seedless watermelon. The would be pollinated by a diploid melon which would only contain 1 set of chromosomes, so that would result in an an odd number of chromosomes again (7). What most likely happens is that occasionally you get 1 set of chromosomes during egg cell meiosis and when pollinated by the diploid male parent (again 1 set of chromosomes as per usual in sexual reproduction) you now have a viable diploid seed.

I think you are confused? Hexaploid = 6 Diploid = 2, 6+2 = 8 is an even number therefore viable seeds are formed. Or if you want to number them in sets specifically 1+3 = 4.

To give people a year 2 update on my own experiment planting seeds taken from a seedless watermelon. This year would be the f3 generation and to my surprise the flowers are self fertile this year. I found this out because my sugar baby pollinator plant got too much water in its location and died off but the f3 plant has been making fruits with its own pollen. Can't wait to harvest one to see the inside. So yea I recommend planting those seeds.

Thanks for the update George, I'm now on Year 3 of my Landrace Watermelon project, which is separate from my seedless watermelon seed project.  I'm excited to see what happens next year when I grow them out.  Keep us updated on your project as time goes on!

Totally delighted to hear all you folks playing with this! I no longer grow much, but I have an AWESOME Farmer's Market, that sees me most weekends, year 'round. I love watermelons. This year I have been checking out different melons, to see which I like best. I got several seedless watermelons from one vendor. We both agreed that they were ripe, but the seedless ones were disappointing. Moderately sweet, but almost no flavor. In reading comment on the webs, I wonder how much people are commenting on the sweetness, not the flavor, and do not realize it? Sometimes you have to train your tastebuds to be aware of FLAVOR, rather than sweetness. Think corn, strawberries, peppers, eggs. I am sure all of you have examples of this.

Sharon,

I just bought a seedless yellow fleshed watermelon & cut it up yesterday.  Nice color, crisp & firm, but no flavor and only the slightest hint of barely sweet.  Needless to say...disappointing.  The only good thing about it was I did get one large plump mature seed to add to my "seedless watermelon saved seeds project."  I came across a deal on some commercial seedless watermelon seeds, so I have a supply to try growing them at home to see if it's just a matter of commercial growers picking before ripe or if they're just lacking in flavor.  I've had the occasional great one, so I think it's just they harvest the whole field on a scheduled number of days after planning to forecast then the stores can expect shipment.

Conversely, I gave my Dad some saved seeds from a commercial hybrid long sweet pepper, and what grew was so delicuiosly sweet, thin walled & crisp, I could've eaten them like apples right off the plant.  I was genuinely surprised at how good it was.

As far as strawberries, I used to have a large patch that I maintained for many years.  While store bought berries are larger, it's because they're full of water, not concentrated flavor.  I actually had to reduce the sugar in my strawberry jam recipe due to the higher natural sugar in perfectly ripe berries.

I agree with you on the eggs as well.  Give me the orange yolks over the pale yellow ones any day.