Open Source Plant Breeding Forum

General Category => Plant Breeding => Potatoes => Topic started by: Lauren on 2020-02-07, 11:20:20 AM

Title: Forcing potato blossoms?
Post by: Lauren on 2020-02-07, 11:20:20 AM
I started some potato sprouts off of store-bought potatoes, and they've rooted well. Not chips, but the sprouts growing out of the potato. I'm wondering if these would be more or less likely to produce flowers and viable seed? I had one potato seedling bloom last year, but it never got berries on it. I'm hoping that a vegetative start without the potato itself might trigger blooming in potatoes that normally don't.

Any ideas?
Title: Re: Forcing potato blossoms?
Post by: Ferdzy on 2020-02-07, 12:10:05 PM
This got me interested so I googled "inducing flowering in potato plants" and look what I found! Some farmiliar names (typo, but seems so apt).

Overall, it sounds like preventing them from forming tubers may indeed increase flowering and seed setting.
Title: Re: Forcing potato blossoms?
Post by: William S. on 2020-02-07, 12:12:26 PM
A couple years ago I bought and read an kindle ebook of a conventional vegetable breeding text. For forcing potato blossoms and berry production particularly on hard to get to bloom types they talked about a common method involving bricks. I guess what you do is you take some bricks and build a sort of a platform with them. Then set some potatoes on it with a very shallow layer of soil. This creates a stressful growing environment in which the spuds are more likely to bloom and produce berries. Apparently this is how they work with varieties that don't commonly produce berries. Though I think they talked a lot about potato breeding someplace like Ireland where it rains a lot. So in a naturally shallow soil and droughty clime its possible that some varieties might produce flowers and fruits more readily than in a more ideal gardening climate. Anyway, stress might be key.
Title: Re: Forcing potato blossoms?
Post by: bill on 2020-02-07, 02:41:43 PM
Sprouts aren't any more likely to flower.  If anything, it is the opposite.  A single sprout produces a plant with a single stem, which has a lower ratio of plant to tuber mass.  It will spend more of its resources forming tubers than a plant with multiple stems.  Also, grocery potatoes are much more likely to be carrying viruses, which reduces the odds of flowering.

The best way to get flowering is to find varieties that flower in your climate.  That is a lot easier than torturing plants until they flower.  But, if you want to go the torture route, the basic idea is to remove vegetative sinks (tubers) so that the alternative reproductive sink (flowers) gets more of the plant's energy.  You can do that by growing plants shallowly and removing tubers as they form.  The trick with the brick is to set it on top of some soil and grow the plant on top of it.  The roots will eventually reach the soil, but the base of the plant will remain exposed so that you can see where the stolons go and easily remove the tubers.  This usually works to some degree for all but the trickiest types (earlies and plants with viruses).
Title: Re: Forcing potato blossoms?
Post by: nathanp on 2020-02-07, 07:06:24 PM
I concur with Bill.  Plants grown from sprouts actually seem to hasten senescence, so flowering is actually less than when grown from the tubers.

Here is two pictures of the suspended tuber method that Bill mentions.


Title: Re: Forcing potato blossoms?
Post by: Lauren on 2020-02-08, 10:02:38 AM
No, I wasn't thinking of getting blossoms from this batch. I was wondering if this would be a process if I ever get tubers from any of my seed grown plants, since they don't seem willing to flower here (yet). I need to get my 2nd generation or the project is dead.
Title: Re: Forcing potato blossoms?
Post by: William S. on 2020-02-08, 11:42:27 AM
I never got a second generation from my first attempt at growing true potato seed. I left them over a winter in the hopes they would produce seed the second year, but they didn't. Then the third winter they winter killed. Sounds from some of the comments like latitude might be important. I've had potatoes that set seed years ago. Actually when I was a kid I got to go to the potato lab in Bozeman MT at MSU and clone a potato. Brought it home in its little tissue culture jar. Grew it, then planted it in the garden, and it set a true potato seed berry. Then I let the berry rot in a jar on my windowsill and lots of seedlings sprouted from it, etiolated and died. So its probably important to get just the right genetics. I was eyeballing one of the cool varieties of TPS on William Whitson's site Cultivariable: a long purple tuber type. Wonder if they would produce berries for me. The TPS seed I still have is from Joseph, I grew some of it out, but he is a about a days drive south of here. Not sure where latitudinally the Cultivariable farm is. Washington State maybe- that is closer latitude wise than Utah, so it might be interesting to compare and see. Just looked it up on Google maps and eyeball wise it seems much closer in latitude. Interesting.
Title: Re: Forcing potato blossoms?
Post by: Lauren on 2020-02-08, 05:04:53 PM
Potatoes used to have berries in our garden all the time when I was a kid. Dad just threw them away. Haven't seen one since. So there must be some varieties that can grow berries where I am (assuming they're not male sterile).
Title: Re: Forcing potato blossoms?
Post by: William S. on 2020-02-08, 05:19:02 PM
Yeah, gotta be.

Title: Re: Forcing potato blossoms?
Post by: bill on 2020-02-08, 06:15:47 PM
It is overwhelmingly more likely that you will find plants that flower and fruit when growing from seed, almost regardless of what variety the seed came from.  Commercial potatoes are typically so heavily selected for everything but flowering that it is effectively selected against.  And the majority of them are male sterile as well.  There are some tough climates where it will just never happen, but if potatoes produce well enough to be worth growing in your climate, they most likely can flower there as well.

Higher latitudes favor increased seed production in short day varieties, but otherwise it doesn't matter very much.  The main factors that make potatoes super-floriferous in my climate are probably low daytime temperatures in combination with high humidity.

As a general rule, I'd say that it isn't worth keeping any seed grown potatoes that don't flower well if your objective is breeding.  Toss them and start more until you find some that do.  Your life will get a lot easier after that.
Title: Re: Forcing potato blossoms?
Post by: nathanp on 2020-02-08, 06:32:12 PM
Many older cultivated varieties are male sterile due to an inherited condition present in chilotanum potato types, so they need a different potato as a pollinator for them to produce berries.  Having highly male fertile potato varieties presents a different problem, as they produce a higher percentage of selfed berries, which often lack hybrid vigor.  The best offspring are usually the result of either hand pollinations, or from potatoes grown adjacent to highly male fertile potatoes, as those often will have a higher percentage of berries that are crossed (hybrid).  Tetraploid andigenum potatoes will generally have a higher degree of fertility because they do not have the chilotanum chromosome deletion that causes male sterility, but they often are not adapted to long day conditions and will not set tubers until day lengths fall under 13 hours (September in the northern hemisphere).  Crosses between chilotanum and andigenum potatoes will fall all over the spectrum with day length adaptation, but in order to avoid the male sterility, you need to use a chilotanum male fertile parent to pollinate an andigenum as the female. 

An easier path would be to start with some of the numerous male fertile potatoes that are available. You really need to start with fully fertile potato varieties, one way or another. Or at least have one good male pollinator if the others you are working with a male sterile.  You can still have some good berry production.

Regarding berry production, there are generally very specific conditions required for berries to set and stay on the plants.  Temperatures generally need to stay under 85F.  Some can handle producing berries up to about 90F, but most will drop the berries under high temperatures. Drought or other environmental conditions can also impact this. The ideal climate would be 60-75F for long stretches of the year, with daily watering. 

I usually get two periods of the year when my potatoes produce berries.  One is June before the highest summer heat, and the other is in late August and September afterwards.  I would also recommend planting several male and female fertile potatoes near each other so they can cross pollinate each other. Bumblebees are the natural pollinator, so planting some flowers that attract bumblebees can assist with that. 

I find that which potatoes flower and produce berries each year is somewhat variable, to some degree for all but the most fertile berry producers.  I'm pretty content if I get berries on average about every two years for each variety/clone I grow. 

This link on the Kenosha Potato Project Facebook page lists many varieties that would be good ones to start with that are not male sterile.  The list is below the link. (

Other than these, I would tend to avoid the majority of cultivated potatoes
Here is the (incomplete) list so far:

North American (USA and/or CANADA)




BOULDER / PI 656384













European (EU)







COMLE (1964)






















ORION (1947)












South American

CHAPOSA (Bolivia)

FRIPAPA (Ecuador)

PERRICHOLI / KABALE (Bolivia, Burundi, Uganda, Vietnam,  Ethiopia,  Guatemala y Peru)


MURUTA (Burundi)

PERRICHOLI / KABALE (Bolivia, Burundi, Uganda, Vietnam,  Ethiopia,  Guatemala y Peru)



PERRICHOLI / KABALE (Bolivia, Burundi, Uganda, Vietnam,  Ethiopia,  Guatemala y Peru)