I’m getting interested PVNA Asian persimmons, but I have some questions. Maybe somebody can help?
I’ve seen individual PVNA varieties described as self-fertile or not self-fertile, differing by source. There is evident confusion. So:
a. Is there a general rule? Or does it vary by name?
b. Is the issue perhaps what I will call technical vs practical self-fertility?
i. As I understand it, a tree is self-fertile if a male flower from the tree (or its clone) is capable of pollinating a female flower from the same tree (or clone). Given this precise technical definition of self-fertility, are PVNAs self-fertile or not?
[Edit: Based on subsequent commentary within the “Persimmons 2022” thread" it seems clear that the PVNA varieties Chocolate and Coffee Cake are both capable of fertilizing themselves. So I infer that PVNAs are self-fertile, given male flowers. ]
ii. On the other hand, some varieties produce more male flowers than others. So a poor producer of male flowers may be technically self-fertile but practically self-infertile because it needs a different, better producer of male flowers. Is that the real issue?
PVNA status depends on production of ethanol by the seeds. Is the behavior of the seeds controlled entirely by the genes of the female or is it influenced by the genes of the male? I know that this may seem a bizarre question, but it seems entirely plausible that seed behavior may be influenced by the genes carried by the pollen.
Asked differently, do growers notice differences in PVNA de-astringency, color, and/or flavor depending on the pollen source? For example, is a PVNA fruit pollenated by Chocolate different from a PVNA fruit pollenated by Hanagosho or Taishu? Is a PVNA fruit from the variety Coffee Cake different if it is pollinated by itself vs Chocolate?
Is it fair to say that an unpollinated PVNA fruit behaves like an unseeded PCA fruit?
What is the degree of parthenocarpy among PVNAs? In other words, will unpollinated fruit hold and ripen?
Is there apparent interaction between seeded and unseeded fruit? I’ve read that the presence of seeded fruits can lead to dropping of unseeded fruits. This would be a sort of conditional parthenocarpy – unseeded fruits develop unless seeded fruits are present. Does this seem to happen with PVNAs?
I realize that some of these questions may sit on the boundaries four knowledge. All input is welcome.
Here is another question. I crossed Tam Kam nonastringent Asian persimmon with Chocolate male flowers. I grew out 12 seeds and they are on the 2nd leaf and all are potted trees. I am just curious what type of fruit shape do I get because Tam Kam is squash and Chocolate is Large oval-shaped . In addition, Tam Kam is PCNA and Chocolate is PVNA then what will the offsprings fruits
Tony – I was looking for answers, not more questions!
My understanding is that PV is a quantitative trait, so the more PV genes the more NA the fruit. [It is not yet known whether the PV trait is controlled by one locus, but I will assume so for this discussion.]. So hypothetically, with 2-3 of six PV genes, you have a PVA; with 5-6 of six, you have a PVNA.
Knowing nothing else about PV genetics, I’m going to assume a simple model. Chocolate is seriously PVNA so I’d assume that it is fairly homozygous. For sake of argument, let’s say 6 of 6 PV genes. Tam Kam is uncertain. As discussed in another thread, some PCNAs display modest PV when seeded. So let’s say 1-2 of 6 PV. Cross them and you’ll get 3 PV from Chocolate and most of the time 0 PV from Tam Kam, so 3 of 6 PV mostly. But sometimes there MIGHT be 1-2 PV from Tam Kam IF (and this is a big if) Tam Kam has any PV genes at all.
Bottom line, I think the crosses will be all (or nearly all) PVA.
Plus, Chocolate would presumably supply 3 A (astringency) genes, Tam Kam 3 NA (non-astringency). Since NA is recessive, the flesh would start out astringent. There’d be no chance of a PCNA offspring.
Consistent with this reasoning, in 2007 and 2009 Japanese breeders released two varieties that resulted from crosses of the PVNA variety Kurokuma x the PCNA variety Taishu. The releases, named Taiten and Taigetsu, are both PVA.
I recall recently reading a more sweeping generalization about the results of PVNA x PCNA crosses, but I can’t find it right now. Stay tuned!
I looked back at the “Persimmons 2022” thread. In the pictures recently posted by @Barkslip, there is no evidence of PV in seeded fruits from Tam Kam (or, for that matter the PCNAs Izu-not and Hawa Fuyu). So you should probably assume no contribution of PV genes to your crosses. With 3 of 6 PV genes, your seedling should be reliably PVA.
Randomly I came across this old paper. Interestingly, it reports measurements of the ethanol content of seeds, ethanol content of flesh, and soluble tannin content of flesh for 7 persimmon varieties as they ripen. As expected:
Ethanol production in seeds is high in three PVNA varieties, low in one PVA varieties and zero in a one PCA variety. Ethanol production differs among two PCNA varieties.
Ethanol content of flesh tracks ethanol production in seeds, lagging by a few weeks.
Tannin content in PVNA, PVA, and PCA varieties tracks ethanol production. Tannin content in PCNAs is uniformly low.
Surprisingly, ethanol production is high in the PCNA variety Fuyu but low in the PCNA variety Hanagosho. Authors note that this ethanol production in Fuyu is consistent with the observation of pollination variance (brown specks) in Fuyu fruits.
Presumably other PCNAs may display brown flesh when seeded, maybe especially PCNAs with Fuyu ancestry.