whole lot of flowering tetraploid spuds

[Steph S]

I was building new/ rebuilding old raised beds this spring and went a bit nuts on the seed potatoes as a perfect fit for planting then filling up with new compost.  So I ended up with ten varieties in 4 beds, and for whatever reasons or conditions a lot of them are ready to flower I'd say in the next week.

Choice of seed potatoes was primarily opportunistic - every hardware store I went into had something different that I thought I'd try.  The only one I've grown before is German Butterball, which is a great potato to grow here because of the scab resistance, but for me they are late, since the beds go into garlic afterwards.  I read in the Oxbow Farm thread that the GB are male fertile while many are not, but also the observation that late parents produce many more late offspring than early.

My personal favorite potatoes are reds.  So I have Norland, Sangre, Cristina, Red Apple and Red Thumb.  I have grown Norland before but not at this site.  Scab resistance is moderate at best.  Sangre is reported susceptible, and Red Thumb has mixed reviews on the scab.  Those are the earliest ones.  Cristina comes next with some scab resistance, and Red Apple later but also said to be resistant.

My preferred potato texture is waxy.  In the yellow fleshed I have Gourmandine probably closest to my likely to be liked best, but mixed reviews on scab resistance.  Yukon Gold which I don't really care for is scab susceptible, Alaska Bloom which I got sent by mistake, a pink eyed white reported resistant.  And one blue fingerling, for my mother not for me I don't like them or want to breed them.

If anyone has experience with these varieties or their parent plants, that would indicate the chances of male fertility, please let me know.

Red Thumb: flowered before the rest and tbh those plants look to be done with flowerbuds at the right stage. but I do have a couple of more plants of RT that were planted later.
Google AI said they are female fertile but pollen fertility is low.  I couldn't find a source to confirm that.  Low is not no fertility, could still be a male parent.
Question: Can potato pollen be collected and stored? Lots of flowers currently open on these.
 
Red Apple: has opened flowers on a couple of plants, others at varying stages of maturity.
From a cross between 'Fontenotte' and 'Romanze'.  Romanze pollen fertility reported high.  Found nothing on Fontenotte nor on Red Apple pollen viability.

German Butterball: has drooping flower buds and a couple of open flowers. Male fertile but late.

Cristina: looks few flowered; buds are at a 'white tip' stage pointing up.
A cross between Rooster (male parent) and an unnamed potato selection not recognized in the search. FWIW Rooster pollen fertility is reported low, but sterility is from the female so nothing is known about C.

Gourmandine: reported to have few flowers but that's not the case here; every plant seems to have a nice cluster of buds about the same stage as Cristina.   Gourmandine is a cross of Charlotte (female parent, pollen fertility low) and Estima (male parent, pollen fertility high).   IDK what are the chances, the pollen could be viable even if low.  So this is one possible weak male parent.

Alaska Bloom: reported male fertile by Google AI but found no text to confirm that.  Buds are slightly more advanced than G and C. a cross between 'Nadine' as the female parent and 'Picasso' as the male parent.

Sangre: has buds in the just perceptible stage.  Scab susceptible.
bred by USDA from the cross (Viking x A6356-9)

Norland, Yukon Gold and the blue fingerling have no buds yet, they were planted last.  Red Thumb planted at the same time have just perceptible buds already.

Another question about pollen:  are there several ways of collecting it?  I looked at Rebsie's blog:
http://daughterofthesoil.blogspot.com/2010/06/how-to-breed-your-own-potatoes.html
and I tried using an exacto on a couple of anthers from two plants but got nothing from either that way.  Any other methods to try?

[Steph S]

I found some helpful videos by a Dutch potato breeder.
This will make it easy to do a few experimental crosses and see if I get any seeds.
Some helpful tips from the videos:
1) Doesn't bother to emasculate.  Says a bit of selfing is okay if it happens, but he doesn't usually get seed from any flowers that he didn't pollinate.
2) Collects pollen by vibration, as is done with tomatoes.  I didn't have a tool, but this morning I tried tapping to collect pollen, as in tomatoes, and voila.  Got plenty.
3)  Advised to do crosses at 9 am not earlier or later in the day, and 20C, not 30C.  I had a shot at collecting pollen yesterday afternoon and a complete fail:  this morning between 9 and 10 am I got lots.
This is very similar to my experience with tomatoes as well.
4) He does some deliberate pruning and tying, as well as growing in small pots and washing out the early tubers, in order to encourage the plants to make true seeds.  I won't be doing that this time around, but I don't doubt these are useful techniques when you're really sure what crosses you want, and maybe also helps to be more controlled when pollen fertility is present but low, for example.
Crossing:
https://www.youtube.com/watch?v=dzkPPAwKvoE
https://www.youtube.com/watch?v=L6arajcYqHQ
The tie-up setup:
https://www.youtube.com/watch?v=QakxINJgMdU
This breeder Boer Jan has a whole channel full of videos sharing his techniques in breeding from start to finish.  Thank you Boer Jan!!

So with pollen in hand, I started a cross this morning with Red Apple pollen on Red Thumb.  Will make some more crosses of opportunity in the coming days, and at least I should learn whether pollen is viable on some of the interesting parents. Or whether a protected setup is necessary to get any seeds here. A bit random, but I can't look at those flowers without thinking about trying for some seeds.

Besides the Gourmandine buds that are getting close to maturity, I found buds on a couple of the Norland plants this morning, for a cross with an actual early.

[Mike Deyo]

I used a different method to make a potato cross, that I read about in a scientific research paper. I liked the taste of Austrian Crescent, waxy yellow fingerlings, but they did not like my climate, or had a virus load, and were not very productive or vigorous. I also had Blue Victor, that was a wonderful grower, but a boring potato. Austrian Crescent never set fruits, while Blue Victor had loads each year, even in the hottest weather. So I knew BV had good pollen.

The method was to take a cutting of AC, just  a bit before it's flowers would pollinate. Put the cutting in a 1 gallon plastic water bottle (or any suitable container), with water in it, I think I had to cut off the top of the bottle and arrange some support to keep the cutting upright. Pollinate a few flowers of the cutting, and keep renewing the water in the bottle to keep it somewhat clean. Amazingly, the fruits can develop and have viable seeds, with no roots in soil! You might want to limit the amount of strong sunshine, so there is not too much wilting. I might have cut off the bottom of the cutting, when it started to rot, to get back to good tissue, at some point while the fruits were developing.

I did get fruits with viable seeds, and when I planted them it was amazing the diversity of growth habits. Some had no dormancy, with the new potato crop spouting under ground and spreading like a weed (not desirable!).  About half of the seedlings set fruits readily, so more crosses among them is possible. I have selected a half dozen to keep growing. One combines the bush growth habit and potatoes clustered near the main stem (like BV) with a more waxy texture like AC.

Also you can save pollen from a early blooming cultivar in the fridge, to use in a later cross, keep dry. I use a glass jar with a small envelope of silica gel. Let it come to room temperature before you open it, to avoid condensation.

[Steph S]

That's a very interesting method to try Mike.  Thank you.

Being a year of trying very different methods of potato cultivation from those I am used to, and maybe also due to the hotter and dryer conditions of the year, I'm impressed with the importance of water for potatoes as never before.  Not only mentioned by the growers who produce in raised beds, but very obvious in the field, where I've had to water to keep the plants from wilting at times.
In the old days, we never watered potatoes.  It wasn't even considered.

I grew a tomato fruit for seeds from a cutting in plain water once. 

Using a cutting would also allow me to protect from the high winds/rain etc that might put seeds in jeopardy in the field.  Will see how the flowers develop and look for opportunities.

[Steph S]

My first attempts at crossing in the field were fails:  Red Apple pollen X Red Thumb.  Possibly Red Apple doesn't have fertile or very fertile pollen, and both attempts dropped.
I then took a Red Thumb cutting from a later planting as it started to flower, and put it in water a couple of days ago.  It has a nice cluster of flowers which open and close daily, and it seems happy in the water..  So far I have attempted to pollinate with Gourmandine and today with Norland, which is producing copious pollen.   Today I took a Red Apple cutting with a nice cluster of buds and two open flowers, and attempted a couple of crosses.  The cutting is drooping, so we'll see if it is adaptable to being kept this way or not.

Noticed today that the Red Thumb does however have a couple of seed balls, as does German Butterball.
The plants are so tall, and it's so windy from time to time, they've been blowing down.  I put up some rails for support, but I wonder whether I'd be better off to take the cuttings with the balls already on them, and let them mature in water as well.  It would be nice to have true seeds, even if they are selfs.
I did notice some bumblebees working the patch, so there could be crosses too.
I'll have to read up on potato gene dominance to figure out what the offspring would be like.

[Steph S]

A couple of developments to report.
Determined that both Gourmandine and Sangre have fertile pollen.

Gourmandine has set a few balls in the field, presumably from selfing.  I may have encouraged that by tapping for pollen, although I noticed that potato flowers are also easily damaged with the same kind of finger tap collection I use for tomatoes, because of the exserted stigmas.

I also have seed balls developing on my Red Apple cutting, from crosses with Gourmandine and with Sangre. 
I have no idea how well the cutting will survive to ripen the seed but at least it's a proof of the pollen viability to add to the list of male fertile potatoes.
There are also attempted crosses on both cuttings with Norland pollen, which haven't yet either dropped or formed a seed ball.   Red Thumb cutting though has dropped all of the other attempted crosses.

In other crossing notes, Boer Jan's advice about early morning pollen collection has been absolutely correct here.  On a number of days I had a lot of watering to do and wasn't finished early enough for the good pollen time window, getting little or none by 11 am and increasing heat.
Potato flowers have some direct similarities to tomato flowers when it comes to making crosses.  When the stigma is fertile, the little knob on the end becomes sticky.  So if you have pollen collected on a lid or lens, you can see that the cross was timed right because dragging the stigma across the pollen leaves a line where it's been taken up.   In potatoes that little knob also seems to darken or turn black when it matures, although I haven't actually put my glasses on to take a closer look.

[Steph S]

Well my Red Apple cutting made seed berries with pollen from Gourmandine, Sangre, and also Norland.  Sadly all those little berries have dropped.
So I'm back to the drawing board in the potato crossing.
I may try the greenhouse culture and techniques that Boer Jan uses, in another year.

But for now at least I have some pollen fertility data for the available cultivars.

[Steph S]

October update:  Mother nature decided I was going to have lots of TPS this year.  German Butterball and Gourmandine produced lots of berries, Red Apple made a dozen or more,  Red Thumb also made a few nice berries, and Norland produced some seeds from a cluster of small berries that it dropped.

I'm assuming that any field crosses would likely be limited by proximity so many of these would be selfed.  I'm not sure how much variation I would expect from a self, but I suppose it depends on the traits of concern and whether there is a strong tendency in potatoes to be adaptive. 
It was, for us, a very dry and very hot summer, with lots of temperatures hitting above potato preferred levels.  I had to water them a lot, and that is a first for me, ever watering a potato plant.  We had half normal precipitation every month from May until the present and are still in drought here. So IDK if the plants were stressed enough by the conditions, to juggle some resistance for the seeds.

Other traits of interest for me: Earliness, scab resistance, early blight resistance, productivity and of course taste.

I also had a few plants clustered together in bags/pots, as an experiment to see if I could get clean seed potatoes that way.  Not a 100% success, but these plants also flowered and several produced a berry or two, including Red Apple, Red Thumb and Gourmandine.   Sangre flowered nicely in the same group but produced no fruit.

So I am processing the seeds from the soft ripe berries now, and thinking about which ones would be easy to assess for crosses. 

Overall Red Apple was my best potato.  Quite scab resistant, productive, very tasty, nutty and sweet.  It is on the later side, so optimally it could contribute resistance genes and other good qualities to an earlier potato.  Red skin and yellow flesh.
Gourmandine is also a very interesting potato. Very high yield, yellow skin, flesh becomes quite a dark yellow after curing a couple of weeks, and the taste is buttery and rich.  Quite scab resistant, but susceptible to Early Blight on the foliage.
Sangre is earlier and resistant to the foliage disease but fairly scabby.  A tasty new potato, red skin and white flesh.  No berries however.
Red Thumb is also earlier, with very small tubers and very scabby.  The pink flesh is very nice and they are tasty but no good for the small size and having to peel them.  These have a big set of dominant genes: the red skin, red flesh, and the antho whorl on early leaves, so it would be easy to spot crosses in seed from another parent.

Would I be right to assume that one allele for those color dominance genes would be enough that they would show up in every offspring of a cross?