Sweet Potato Breeding Project

[richardw]

May 6, 2017 6:56:15 GMT -5 philagardener said:

I wonder if NZ varieties (which apparently date back to the Maori) are more fertile than the ones grown in NH?

Maybe richardw would know.

Kumara its called here, and no they appear to be less fertile to what you guys grow, flowers are very uncommon, i know someone who lives up north where its close to subtropical, he had a flower on one of his Kumara which was the first time he had seen one, i sent him a link to this thread so he could read about, he's going take more notice next growing season. I grew three different old Kumara varieties this past summer (white, purple and a orange) only the orange grew tubers, i'm a bit too far south for them to do really well.

[reed]

I just assumed from watching the video that they bred their kumara by seed but maybe they just selected roots that didn't rot and the odd nature of mutation I'v read abut in sweet potatoes did the rest. It also sounded like they had a pretty large operation so chances were higher of new things showing up. 

[richardw]

Each of the many different Maori villages post-European colonization grew there potatoes from TPS but not the Kumara. It was pretty much grown the same as Taro further north by there earlier ancestors who settled the Polynesian islands, by way of root division. I'm sure Taro was bought here too along with the kumara but it would have sown itself to be to cold to do well. When the potato was introduced to Maori they really take a strong preference for it because of its shorter growing season. In my neck of the woods pre-European were known to use dark coloured rocks amoung there young spring grown Kumara to achieve a long grown of a growing season, remembering too this was pre-climate change days, some of the winters back then must have bin brutal .

[richardw]

An interesting link explaining the history of Kumara - www.temarareo.org/PPN-Kumala.html

[reed]

Thanks for the link richardw, I've been having fun reading everything I can find about this crop. I'v saved and printed most of it, up to probably 200 pages now. Certainly an interesting plant. Who knows how much of the info I'v found is truly accurate but I remember one paper that indicated that what we know as sweet potato might actually be a recent, on an evolutionary scale of two or even more other Ipomoea species. That might explain their habit of mutating on their own even when cloned which in turn explains so many varieties from a plant that rarely makes seeds.

Then another source says a new sexually produced plant can  revert to it's mother's phenotype the few times it is cloned or to an entirely different phenotype.  

Then info that some are male sterile some female sterile and some both. None are supposed to be self compatible but I strongly suspect that might not be entirely true and hope to find out for sure this year.  
  

[richardw]

Got me thinking now, does the NZ Kumara rarely flower because of the latitude or is there something else at play here, where most of NZ's Kumara is grown is about 38S. What latitude are you guys who manage to get good flowering.

[reed]

Interesting, I'm at 38 N so I guess latitude isn't the issue. Flowering really picked up last year after the summer solstice.

[richardw]

Well there you go, why doesnt it flower?, would it be virus load?, can potato viruses be transmitted to sweet potatoes......

[reed]

I got my pots ready last night to plant my sweet potatoes, gonna just go ahead and set the seed grown ones out I think, they are still in their trays where I started them and too big to mess with up-potting, plus it is plenty warm. Actually have several more sprout all of a sudden. I'm more sure now that heat is what they like. Sitting on the table in full hot sun at 90 degrees, in a black tray, the temp must be over 100. Two or three per day have sprouted last three days. I'm thinking now I should keep them all but will be tagging the first sprouters. First sprouters get a tag, 2-S plants get a tag and a couple will end up with two tags. 

Next year I am not going to start them till at least first of May, maybe a little later. I have plenty of hot season, no need to push it early. I'm thinking of getting some out of back up and seeing what happens just putting them in that same set up. I'm starting to suspect direct seeding is possible.

It's also time to pull the slips. One of mine, I think it is Patriot still hasn't sprouted but it is rooted down good and not rotted so I imagine it will.

I decided to crowd them all into just six to eight large pots. I'm after seeds right now, not root production. Or to look at it another way I'm lazy and gathering, moving, shoveling enough dirt to fill up twenty of those big pots just didn't sound fun. I'll plant a small row in the ground for roots to eat.

[reed]

I don't know that it matters much, just though it was interesting. The reading I did on scarifying by filing the seed said to file the edge, not the round side of the seed which makes sense and that is what I did on the ones I scarified which by the way did not sprout.

To me the edge is the sharp corner where the two flat sides meet but that is not where the seed splits when it sprouts. Sorry about the poor image quality but here is one that came off intact. If you look close you can see the seed opens just under the little dent, not along that angled edge so if filing the seed I would say to just very gently file there instead of on the angled corner.



Also I have had some issue with the seed coat not coming off the sprout. Generally I think planting the seed round side down could help with that as it the seed coat gets dragged off as the seedling emerges. Another remedy is to apply drops of water or mist it to keep it soft, they pop right off then. Attempting to pull it off is a mistake.
I do wonder though if filing the area that does split might make it even harder for the seedling to shed the coat because it might sprout before the coat has had time to soften up. 

Not sure any of it is all that important though cause sitting out in 90 degree sun they pop up all over the place anyway. I was expecting germination of 10%, it is closer to 20% or a little more. I bet if I had waited to start them now it would been higher as some have probably rotted by now. 

[reed]

Seeds keep sprouting including some that came up alongside larger ones already planted out. There were originally 2 - 4 seeds in each cell so unsprouted seeds were transferred along with the larger seedlings. Not sure what to do with those, should I remove them or just let them be crowded together? The bigger ones are already established and don't want to disturb them by trying to transplant out the little ones. I don't mind crowding since I'm primarily looking for seed production but having come from the same little cell these are extra crowded. Since they are in with the original fast sprouting plants I think maybe I should pluck them out.

Very generally I think germination rate is around 25%, much higher that I expected and I think it can be increased next year by waiting till at least first of May so they can be more easily kept warmer and exposed to direct sun sooner.

[steev]

That is interesting; I'm always intrigued by the unexpected; one never knows where it will lead: always an adventure.

[reed]

That is amazing, volunteer sweet potatoes that far north. You may have the start of your own new varieties that would give you the insurance of having a crop the next year even if something happened and you lost your stored roots. Not to mention they are adapted to your climate.

[imgrimmer]

Sounds great! Blooming, selfed or crosspollinated, self seeded and frost resistance in seeds this is a perfect combination to start with.
I am just after varieties that set seeds for me. Cold tolerance is still out of reach.
If they set seeds again I would be highly interested.

[reed]

I closely inspected the area where my sweet potatoes were last year. I was pretty thorough in collecting the seeds but thought I might get lucky but found nothing. Then later I was hoeing around my potatoes and low and behold a volunteer sweet potato! That area is where I pitched a lot of old vines last year.
Unfortunately I found it with the hoe    it was cut maybe an inch below the ground and had some little white root nubs above the cut so I put in a little clear cup with some clean sand and brought it in. It was wilted terribly this morning so I cut the larger leaves from the bottom and just left the smallest top leaves. The stem has now started lifting back up so maybe, just maybe it's gonna make it. 

So, now I 'm amazed again.