My 2 cents:
<< If the C-PCNA and J-PCNA genes are different, wouldn’t it behoove us to cross both of them to gain BOTH sets of non-astringent genes in one “super Asian persimmon”? I would hypothesize that having both dominant AND recessive genes exhibiting half of the traits we desire (cold hardy /non-astringent) would make the task of selecting for a better tasting/larger hybrid more successful. >>
To produce fruit for eating, I don’t see the point. You just need one viable path to non-astringency.
To produce cultivars for breeding, we need to maximize the odds of getting the right genes in the right places. So I think we mostly need (1) a male-flowering J-PCNA (e.g., Taishu) with good fruit characteristics, and (2) a male-flowering C-PCNA with as many non-astringency genes as possible. By necessity, the J-PCNA would be homozygous. Ideally, the breeding C-PCNA would be also homozygous. #1 is required to propagate ANY non-astringent variety based on the recessive J-PCNA gene. #2 is required to increase the proportion of non-astringent hybrids that would result from crosses.
<< Further- for the sake of speeding up the process and making it less complicated if breeding in colder zones, would it make sense to begin with a cross of DV & C-PCNA as C is dominant, then back cross to J-PCNA for improvement? Am I over thinking this? Should J-PCNA even be included? >>
There are two strategies, I think: (1) As discussed above, generate a F1 cross of DV x J-PCNA (e.g., Josephine x Taishu); then generate an F-2 back-cross x J-PCNA. A small proportion of the hybrids should be non-astringent. (2) Generate a F1 cross of DV x C-PCNA. A high proportion of the hybrids should be non-astringent. Either/or works. Both/and seems unhelpful.
<< Based on what I have read, it seems J-PCNA is preferred due to better taste, however if DV is a great improvement in taste, maybe it will make an exceptional hybrid simply with the dominant genes of C-PCNA… >>
Sure. We won’t know unless we try.
To create an improved Kaki, it seems the most efficient approach would be to cross a tasty, astringent variety PCA /PVA variety x a C-PCNA variety. The 1st generation might be great. If not, and if we could get 2-3 C-PCNA genes into that F1 cross, then it would be efficient to re-cross the hybrid with another tasty astringent variety. So we might quickly produce a non-astringent Saiyo or Hachiya.
To create an improved Virginiana, it’s critical to know how J-PCNA and C-PCNA genes will operate in a Virginiana cross. If the J-PCNA genes can curtail the production of tannins in a hybrid, then the F2 generation (e.g., JT-02 x Taishu) could succeed. If the C-PCNA genes can render those tannins insoluble, then the F1 generation (e.g., Barbra’s Blush x Luo Tian Tian Shi) could succeed.
<< I also wanted to point out - just because the big operations use thousands of trees to select one good tree, that doesn’t mean that a planting of 200 wouldn’t produce one amazing tree, it’s just statistically less likely. >>
Right. It’s a lottery.
<< An aside - having concurrent trials for gaining better Asian genetics and then crossing those in a colder zone as a “sister project” seems to be a good way to move forward if possible… None of us are getting any younger. >>
I just turned 70, so I agree wholeheartedly. If it works, the cross described above of C-PCNA x DV would be the most direct approach. That would get non-astringency from the C-PCNA and cold hardiness from the DV. If other attributes such as size and flavor need further improvement, the next step would probably be a cross of the hybrid x a large, tasty astringent Kaki.