In the inventory for England’s orchard, there are MANY listed hybrids of a DV x HKD pattern, where HKD is the Kaki variety Hikkaido. For example (and this is a very partial list):
Row 1, #6. Prok X HKD Female
Row 1, #10. Prok X HKD Hybrid
Row 1, #15. Prok X HKD Kaki O
Row 3, #13. Prok X HKD HYD
Row 4, #4. MB X HKD F
Row 14, #7. MB X Hokkaido O
Row 15, #3. GenevaLong(GL) X HKD F
Row 16, #3. GL X HKD F
Row 17, $4. GL X HKD F
Until now I believed that the only extant direct DV x Kaki crosses were Rosseyanka and JT-02. Are we supposed to believe that Cliff has a couple dozen direct DV x Kaki hybrids? I assume not, but what’s going on?
Another less critical question – Why does Cliff have Prok as the male? I understand that Prok is 100% female. Mine is.
Prok is definitely a female. Hokkaido produced lots of male flowers. @Bass stated in 2017 post that he was able to cross Hokkaido to all his kaki and Hybrids and got seeds. So that is possible.
Looking at what Bass wrote, it is clear that he crossed Kaki x Kaki (e.g., Hokkaido x Saijo) or Kaki x Hybrid (e.g., Hokkaido x Rosseyanka). He does not mention a cross of Kaki x DV. That’s what’s remarkable about Cliff’s crosses. It’s Hokkaido x DV varieties.
As noted, there are only two well-known cases of a successful direct DV x Kaki cross, which produced: (1) Rosseyanka and (2) JT-02. Both of these crosses required embryo rescue. Both of these crosses opened the door to subsequent, much easier crosses of the F1 offspring with other varieties from both species, DV and Kaki.
So if Cliff successfully crossed DV x Kaki without embryo rescue, then he achieved something absolutely extraordinary. Moreover, we should be using the offspring in further hybrid development.
I assume that all of Cliff’s DV parents served as the “female” pollen recipient. Prok is only female; Morris Burton is mostly female but reportedly can produce male flowers. IDK about Geneva Long. But the DVs have a definite female bias. In some cases, Hokkaido can be only male, as Bass reports. But then Cliff shows photos of Hokkaido fruits and he labels some of his trees “F” or “Female.” So apparently Hokkaido can serve as both “female” and “male.” In Cliff’s listing, he always has the DV variety first, which signified the female / pollen recipient. I’ll assume that was deliberate and accurate and that the DV’s were the pollen recipients.
So here are the possibilities:
The DV x Hokkaido crosses are true DV x Kaki hybrids. If so, then Cliff has achieved something remarkable and unique – hybridization of these species without embryo rescue (at least I’m not aware of any embryo rescue). If so, we should use these offspring in further crosses.
The DV trees were pollinated by the trees labeled “Hokkaido” but the label is wrong. That is, “Hokkaido” is in fact a DV variety or, more likely, is itself a DV x Kaki hybrid such as an offspring of Rosseyanka. This possibility may be remote, but it has to be considered.
The DV trees were pollinated by a Kaki “Hokkaido” but also by other neighboring trees, either DV or hybrid, probably by open pollination. In this scenario, the deliberate (hand?) pollination failed while an unintended (insect or airborne) pollination succeeded.
Maybe there are other scenarios. These seem the most likely.
I realize that some people are going to be really pissed off at me because I dare to question. But please understand, I am only trying to ensure that we use our time efficiently. If Cliff achieved an actual third/fourth/fifth DV x Kaki cross, then we should capitalize on the success and use the offspring for future breeding. If not, then we should not waste the time.
I wouldn’t write off the possibility of Dv x Dk crosses being impossible without embryo rescue entirely. There’s a lot of genetic diversity in D. virginiana. Less so in D. kaki but still a good amount. Most of the kaki cultivars we have in the West are from Japan, which represents a tiny sample of the genetic diversity that’s out there, mostly in China. I would argue we simply haven’t tried enough crosses to have a definitive answer. Some combinations might be more compatible than others.
Take peonies for example: crossing herbaceous and woody peonies was long thought impossible. This was proven wrong in the last century, but it took the right combination of parents for the cross to be successful. Had no one tried the two parents that worked, we might still think the cross is impossible.
<<Field studies of the persimmon species, cultivar and form collection, hybridization and station testing of hybrid seedlings have been conducted in the orchards of State Enterprise Experimental Facility “Novokakhovska” of Institute of Rice of the National Academy of Agrarian Sciences of Ukraine (Kherson region). In vitro seed germination of and two-year hybrid persimmon seedlings growth has been carried out in the Department of Genetics, Breeding and Reproductive Biology of Plants of the National Dendrological Park “Sofiyivka” of the National Academy of Sciences of Ukraine. >>
I think what this means is that trees are grown and pollinated in the warmer facility in the south (Kherson) but seeds are germinated and seedlings are grown for 2 years in the colder north/east (closer to Kharkiv) but in a lab. “In vitro” (i.e., in glass, such as test tubes and Petri dishes) signifies that the seeds aren’t just tossed in the ground.
This sentence from the abstract, "In vitro technologies have been used in the tissue culture laboratory of the “Sofiyivka” Dendrological Park for germination of interspecific hybrids seeds, which have insufficient germination in the field. "
and these two I Google-translated from the results section:
"This variety needs improvement in terms of maturity, which is relatively late in Kolhospnytsia, which determined the direction of selection with the resulting hybrids. "
“153 two-year-old hybrid seedlings obtained from in vitro germinated seeds and grown in containers (of which only 12 seedlings belonged to the offspring of Kolhospnytsia) were brought to the Novokakhovske State Farm.”
suggest that the procedure was not embryo rescue, which typically involves removing the embryo from very young seeds to culture before development stops and the fruit is aborted due to genetic incompatibility for endosperm development. This procedure would not be described as “in-vitro germinated seeds.” What these sentences make it sound like is that the seeds were harvested from (open pollinated, btw) more-or-less mature fruits and sprouted in vitro rather than the usual method of sowing seeds. Probably because the Kolhospnytsia parent matures too late in Ukraine and seed development may not be complete by the time the fruit needs to be picked, namely the seed coat hasn’t fully hardened and embryo dormancy is incomplete. In vitro germination would protect the immature seeds from attack by pathogens, as well as allow the use of hormones to circumvent stratification, where I can see the potential for high seed mortality if the seeds are not fully mature. Add that to what’s probably already a low percentage of viable seeds due to it being a wide cross and in-vitro germination starts making sense.
This means that with a sufficiently long growing season and large enough number of controlled pollinations and resulting seed, it’s probably doable to get seedlings from D.v. x D.k. without the help of in-vitro techniques.
Thanks. That’s a very helpful explanation. So the Ukrainians were not using embryo rescue routinely.
The question remains (my commitment to “fact check”) what they did to produce Rosseyanka. Note that in >50 years of breeding, the Ukrainians have released just this one DV x DK hybrid. It obviously isn’t easy.
Moreover in all the rest of the world, there is only one other DV x DK hybrid, which was produced by embryo rescue – JT-02. Again, it obviously isn’t easy.
And then there is Cliff’s collection with dozens of reported direct DV x DK hybrids. I stopped counting when I got to 36. There are at least 4 DV females (Prok, MB, Geneva Long, Keener) but only one Kaki male – Hokkaido. So either there is something extremely special about Hokkaido or there is something extremely odd about the crosses.
I’m not saying that it is not “doable to get seedlings from Dv. x D.k. without the help of in-vitro techniques.” I’m saying that it is not so easy (normally) that one grower should have >40 of them. So there’s some anomaly.
If those D.v. x D.k. ‘Hokkaido’ cultivars are indeed the real thing, then yes, I would guess that something about ‘Hokkaido’ is special.
As far as I can tell, most of the people doing American x Asian crosses are working with a very restricted Asian gene pool. The Ukrainians and Americans looking for hardiness are usually limited by the cultivars that will survive locally. If you’re working with PCNA parents, your genepool becomes even more limited.
It seems that hybrids tend to be fertile despite the difficulty involved in producing them. And hardiness is entirely from the D.v. parent. I don’t think the right way to go is by crossing D.v. with the hardiest kakis. It’s too limiting. Someone living in a warm climate should try a bunch of crosses with as many kaki and virginiana cultivar combinations as possible to see which are most compatible. They don’t even have to grow out the seed, just test if they’re viable.
It was my understanding Churchupaka persimmon is also a hybrid but is just not sold that much in the USA. Is churchupaka not a hybrid? To edit there is another major cross I know how named Nikita’s Gift.
All the other hybrids are subsequent generations (e.g., Kaki x Rosseyanka). Chuchupaka is Nikita’s Gift x Open Pollination (OP) Kaki. Those crosses are easier than first time Virginiana x Kaki.
Southern Ukraine (e.g., Kherson, Crimea, Odessa) seems quite hospitable to persimmons. The problem is that the Russians/Ukrainians were mainly trying to develop more cold-hardy hybrids that could grow on the colder steppe, such as near Kharkiv.
I agree with you that restricting breeding efforts to the most cold-hardy kakis is limiting, probably unnecessarily so. One of the most cold-hardy hybrids around is JT-02, a cross between Josephine (DV) and Taishu (DK). Taishu is not especially cold hardy. It’s in that tender PCNA group.
Thanks Ram. OK, probably I was misinterpreting what I read about the Ukrainian “in vitro” lab work. Thanks for clarifying.
But we shouldn’t miss the forest for the trees – whatever they did was difficult. The Ukrainians managed to produce a viable DV x DK cross only once that we know of. Cliff’s reported success producing 10-15 each year 2012-15 demands attention.
I think Cliffs notation simply says it is a hybrid. Not an F1 hybrid. The first one is probably a seedling of the parent. For instance Prok is probably a hybrid seedling of Prok. He might be writing this way to conserve space. (Margins were too small etc)
Ram – Nice try, but think it thorough. If there were prior hybrids of Prok, Morris Burton, Geneva Long and Keener, we’d know it. Do you think that 10-15 years would have passed without anyone knowing about these prior hybrids? It would have been news. Moreover, at least one each of the four hypothetical prior hybrids would be listed in Cliff’s inventory attached to a date at least 3-5 years earlier, e.g., 2005-2010.
Instead, there is NO instance of a hybrid of Prok or Morris Burton or Geneva Long or Keener prior to 2015. Moreover there are only two apparent hybrids after 2015, both Morris Burton, one in 2017 (“A33 & MB”) and one in 2020 (MB x F100).