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General Category => Plant Breeding => Topic started by: Jeremy Weiss on 2020-11-19, 02:47:08 PM

Title: Walnut species hybridization project
Post by: Jeremy Weiss on 2020-11-19, 02:47:08 PM
Hi all,

I now have most to all of the seeds for my proposed walnut hybridization project; making a hybrid cross between Hind's Walnut (Juglans hindsii) and the Manchurina Walnut (J. mandishrurica) .

The goal of this cross is, naturally, to get the best of each parent.

 From Hind's I want its unusual (for a not regina walnut) tendency for producing nuts which are comparatively smooth of shell (which makes cleaning them for storage MUCH easier than it is for say J. nigra)

From the Manchurian I want it's EXTREME cold tolerance (it can take temperatures so low it can comfortably grow in Southern Alaska). Hopefully this will offset Hind's tendency (being from North California)  of being a little cold intolerant.

As far as I can tell, the actual crossing   should be pretty easy. Both parents cross readily with J. regina (TOO readily in the case of Hind's where it is now hard to find pure stock) so they should have no problem with crossing with each other.

The only hard part (as I see) or rather time consuming part, will be growing the trees from nuts (plus eventually working out how to graft them, as I am not adroit)

Wish me Luck!
Title: Re: Walnut species hybridization project
Post by: Garrett Schantz on 2020-11-19, 04:42:48 PM
I would buy grafts from somewhere. Walnuts usually don't produce nuts until they are around 10 13 years old from seed. Grafts are around 5.
 The F1 should be all pretty much uniform, but that is another 10 - 13 years. After that you would have to plant out the F2, F3 which is where you would begin selecting out traits. Walnuts can cross freely as well. So you would need to plant the offspring in a different location each time to prevent segregating backcrosses.

 Suppose problem with buying them would be lack of availability. Watershednursery sells Juglans hindsii potted, but it is out of stock and I am unsure of how old the plants are. Vdberk sells J. mandishrurica.
 Another problem is that the crosses probably won't be as cold tolerant as mandishrurica. Crosses with cold hardy species of orange have shown this, as have tamarillos and other species.
 This could possibly be fixed with backcrosses, but this could be annoying as you will probably need to select for larger/smoother nuts which mandishrurica backcrosses could eliminate.
 
 Sounds time consuming, but good luck.
Title: Re: Walnut species hybridization project
Post by: Jeremy Weiss on 2020-11-19, 04:57:01 PM
Well, my hope was that, by the time the seedlings were graftable, I'd have worked out how to graft one onto the other (preferably Hind's onto Manchurian, as it makes more sense to have the tougher one be the one with the roots) (or I can use the black walnut I already have as the rootstock and save myself more time). And keep grafting each time to speed things up. (at least until I start selecting, in which case I have to graft each one to it's own rootstock and segregate them, as you said)

It's the loss that is why I picked mandishurica as opposed to nigra or another North American walnut. I'm hoping for an average; something that will take down to maybe zone 4.

Not sure size you be a problem as Mandishurica nuts are about as big as Hindsii. Pitting seems to average out, based on what I have seen of Mandishurica Regina hybrids (I don't need something perfectly smooth, just something where the pits are shallow enough you can empty them out with a scrubbing pad.

With the Watershed Nursery trees, I'd also be worried about purity. A lot of Hinds trees are so full of Regina DNA they're functionally Paradox walnuts. Paradox is a perfectly fine tree in and of itself, but I worry that, as Regina isn't all that cold tolerant either it would drag the total down.





Title: Re: Walnut species hybridization project
Post by: Richard Watson on 2020-11-19, 09:27:53 PM
Can you fella's tell me how to grow the nuts, I try recently with no luck.
Title: Re: Walnut species hybridization project
Post by: Garrett Schantz on 2020-11-20, 05:46:13 AM
Manchurians are described as having a thick shell.. Wikipedia says this about Manchurians "The kernels of the nuts are edible, but small and difficult to extract"

 Can't find much information about hindsii's thickness or anything. Usually the wood is used, assuming the lack of information about the nuts is because they probably aren't harvested. There is apparently only one pure stand. I'm sure more have been planted.

 I usually plant them in the ground at the end of the season, but for New Zealand you will probably need to try cold moist stratification for about 2 months minimum. Scarification might work better for thicker shelled species.
Title: Re: Walnut species hybridization project
Post by: Jeremy Weiss on 2020-11-20, 06:59:38 AM
Hindsii are pretty thick too. Like a Black Walnut, you need a hammer to break it.

As for more being planted, yes an no. In California, Some growers use Hinds as a rootstock for Regina. If those rootstocks develop branches, it isn't unusual to get Hybrids reminiscent of Paradox (the Hinds Regina cross developed by Luther Burbank as a street tree). But Hinds on hinds isn't all that common.

Also check what your climate it. A lot of Walnuts don't like it too hot either. I have no idea how hot South Island is. But if it is more tropical, you may do better with one of the South American Walnuts, like J. boliviana, J.peruviana, or J. chilense.   
Title: Re: Walnut species hybridization project
Post by: reed on 2020-11-20, 08:00:19 AM
Can you fella's tell me how to grow the nuts, I try recently with no luck.
What kind have you tried? I'm mostly only familiar with our wild black walnuts and a little bit with store bought English walnuts, both sprout and grow easily just planted in the fall and covered with a board or rock till spring.

I really didn't know there were so many different kinds.
Title: Re: Walnut species hybridization project
Post by: Richard Watson on 2020-11-20, 11:32:26 AM
I didnt know there were so many kinds either.

The nuts came from a local tree that produce large shells that could be pulled apart by hand. I was told to remove seed from the nut, sow in autumn and let the winter frosts do the stratification, but nothing.
Title: Re: Walnut species hybridization project
Post by: Jeremy Weiss on 2020-11-20, 12:22:36 PM
Well, first of all, you shouldn't be removing the nut from the shell (actually, if you CAN remove a walnut from it's shell without it breaking into pieces, I'm impressed*.) The naked kernel is more or less guaranteed to rot.

If you can pull apart the shells by hand (assuming you mean the shells, not the husk) it sounds like you have an English or Persian Walnut, J. regia the same kind as is grown commercially.


* assuming that it is an common walnut the kernel should look sort of like two brains attached to each other. If it looks like a puffy heart (i.e. does not have any bumps on the kernel) then what you have is either a Japanese Walnut (J. aliantifolia) or it's subspecies, the heartnut.
Title: Re: Walnut species hybridization project
Post by: Andrew Barney on 2020-11-21, 04:34:31 PM
Good luck on your project!

There is a hybrid walnut sold by a company in England that sells a hybrid between the american black walnut and the typical eating walnut I believe. Someday I want to purchase a few.

https://www.walnuttrees.co.uk/shop/walnut-timber-trees/ng23-hybrid

https://www.walnuttrees.co.uk/shop/walnut-timber-trees/mj209-hybrid
Title: Re: Walnut species hybridization project
Post by: Richard Watson on 2020-11-23, 10:36:48 AM
Well, first of all, you shouldn't be removing the nut from the shell (actually, if you CAN remove a walnut from it's shell without it breaking into pieces, I'm impressed*.) The naked kernel is more or less guaranteed to rot.

If you can pull apart the shells by hand (assuming you mean the shells, not the husk) it sounds like you have an English or Persian Walnut, J. regia the same kind as is grown commercially.


* assuming that it is an common walnut the kernel should look sort of like two brains attached to each other. If it looks like a puffy heart (i.e. does not have any bumps on the kernel) then what you have is either a Japanese Walnut (J. aliantifolia) or it's subspecies, the heartnut.
  The kernel was a brain shape and was simple to remove from the shell in one piece.

I will get more seed again May next year and try again.
 
Title: Re: Walnut species hybridization project
Post by: Jeremy Weiss on 2020-11-23, 10:57:22 AM
Hmm, that variety must have really papery inner walls.
Title: Re: Walnut species hybridization project
Post by: orflo on 2020-11-23, 01:06:55 PM
The juglans regia walnuts need moisture and germinate even if the temperatures aren't too high.  I harvested mine about six weeks ago, placed them in tubs, outside, in the back of the garden, to avoid a rat infestation, and they started to germinate now  in these tubs, after these six weeks or so.  We had some colder nights (maybe 4 or 5), but day temperatures were also unseasonally high. So I suspect they don't need stratification.  The ones here are very hard, but clearly j. regia.  I use a bench screw to crack them, a hammer works as well but the result can be quite a mess because they do need a hard blow...I could send you some , Richard, but there could be import restictions for these, and secondly, they're no fun to crack (but very tasty!),
Frank
Title: Re: Walnut species hybridization project
Post by: galina on 2020-11-24, 02:15:40 AM
I would buy grafts from somewhere. Walnuts usually don't produce nuts until they are around 10 13 years old from seed.

I know absolutely nothing about walnuts, but I watched a chance seedling at a neighbour's garden produce nuts 5 years later.  Was that a fluke?  Definitely not a grafted walnut.  Good luck with the project.
Title: Re: Walnut species hybridization project
Post by: Richard Watson on 2020-11-24, 12:42:24 PM
The juglans regia walnuts need moisture and germinate even if the temperatures aren't too high.  I harvested mine about six weeks ago, placed them in tubs, outside, in the back of the garden, to avoid a rat infestation, and they started to germinate now  in these tubs, after these six weeks or so.  We had some colder nights (maybe 4 or 5), but day temperatures were also unseasonally high. So I suspect they don't need stratification.  The ones here are very hard, but clearly j. regia.  I use a bench screw to crack them, a hammer works as well but the result can be quite a mess because they do need a hard blow...I could send you some , Richard, but there could be import restictions for these, and secondly, they're no fun to crack (but very tasty!),
Frank
Thanks for the offer Frank but they are a restricted variety here. Besides walnuts are so common meaning there lots to select seed from. I'm keen to get some of these easy opening nuts to grow
Title: Re: Walnut species hybridization project
Post by: Diane Whitehead on 2020-11-30, 11:28:05 AM
Just for fun - this doesn't apply to your project.

I am reading A Gardener Touched with Genius, The Life of Luther Burbank by Peter Dreyer.

Beginning in 1877 he hybridized walnuts using more than a dozen species and varieties.

One F1 was partially sterile but its F2s were extraordinarily variable.

"bush-like walnuts from six to eighteen inches in height side by side with trees that have shot up to eighteen or twenty feet; all of the same age and grown from seeds gathered from a single tree.  This rate of growth continues throughout life."
Title: Re: Walnut species hybridization project
Post by: Dominic J on 2020-12-25, 07:15:01 AM
Does anyone have any information on triploid walnuts?

I've seen some articles where they want to, and succeed, in creating triploid walnuts. But they don't say *why* they want to do that, or what the results are in terms of fruit bearing. I'm assuming these guys are after the lumber, and not the fruits? Because triploids are generally seedless. For example, one article I read about triploid peaches (or was it cherries?) trying to have pitless fruits just had hollow pitted fruits. But with nut trees, the kernel's what we are after...

In some species, tetraploids have bigger fruits than diploids, in others, they have smaller fruits. Anyone have any insights as far as tetraploid walnuts go?
Title: Re: Walnut species hybridization project
Post by: Jeremy Weiss on 2020-12-25, 09:24:31 AM
They may also be after the trees themselves, for use in urban settings. Walnuts are considered attractive trees, but the pollen and nuts are considered a detriment in urban settings (pollen to mess up cars, nuts to dent them, and of course, nuts lead to booms in populations of squirrels and other such creatures). Paradox was originally designed as a street tree, from what I have been told (there must be two versions, one sterile, one fertile).
Title: Re: Walnut species hybridization project
Post by: Dominic J on 2020-12-25, 06:33:38 PM
That's a fair point.