BREEDING A COLD-HARDY, NON-ASTRINGENT HYBRID PERSIMMON CULTIVAR

View the project report

Commodities

• Fruits: persimmon

Practices

• Animal Production: genetics
• Crop Production: agroforestry, plant breeding and genetics, silvopasture
• Education and Training: networking, on-farm/ranch research
• Pest Management: genetic resistance
• Production Systems: permaculture

Growers throughout North America and in the southern NC-SARE region have realized that persimmons are one of the simplest fruit crops to grow without pesticides and heavy fertilization. Persimmons resist many diseases and increase consumer access to local, nutritious food. As more and more people grow this fruit, the public is acquiring a taste for all types of persimmons. But for many people, non-astringent persimmons (such as ‘Fuyu’) are still considered the most desirable. Unlike astringent cultivars, non-astringent varieties can be shipped and eaten while they are still firm.

Breeders have labored to develop persimmon varieties that produce desirable fruit and also tolerate the winter conditions found throughout the southern NC-SARE region, however their work is far from finished. Cold-hardy hybrids between wild persimmon (Diospyros virginiana) and the oriental persimmon (Diospyros kaki) have been released and eagerly received by growers, but so far there have been no non-astringent hybrid persimmons released to growers in the NC-SARE region. This means that growers cannot easily compete with consumer expectations set by California and other warm regions. As of now, non-astringent persimmons primarily grow in zone 7 and southward, which excludes all of the NC-SARE region. But this could potentially be changed.

Persimmon breeders must focus their efforts on developing a non-astringent hybrid persimmon variety that can withstand temperatures commonly found in the southern portions of the NC-SARE region. Doing so would make an easy-to-grow and nutritious food item available to growers throughout the southern NC-SARE region and in other parts of North America. I have been working with a few others on a plan to tackle this problem.

I will describe below the genetics behind my proposal, but in short, we have determined that backcrossing the 50/50 Diospyros kaki/Diospyros virginiana hybrid persimmon known as Mikkusu (aka JT-02) to a non-astringent cultivar such as Hana Fuyu could potentially generate a new cold-hardy, non-astringent hybrid cultivar of persimmon suited to parts of the NC-SARE region where non-astringent persimmons are currently very difficult to grow. Replicating this cross up to 1000 times will greatly enhance our chances of generating the desired variety or varieties.

Persimmons have complicated genetics, but the strategy proposed here has been affirmed by numerous enthusiasts. Typically, the non-astringent trait in persimmon is inherited recessively. Couple this with the hexaploid nature of persimmons, and it's understandable why generating F1 non-astringent cultivars is difficult. For this reason, researchers have resorted to carefully-planned backcrosses in traditional breeding programs. And in the case of hybrid persimmons, the backcross we propose is similar. It fits the following form:

(American persimmon x non-astringent Asian persimmon) X non-astringent Asian persimmon

To launch the project, I am working with a few sources to secure the pollen I need for this breeding work. I'm in touch with Jenny Smith at the National Clonal Germplasm Repository. She has agreed to send any pollen she can collect from the UC Davis repository. Since pollen can be scarce, I am also making connections with private parties who may be able to supply pollen if needed. Pending successful acquisition of pollen, I intend to hand-pollinate flowers from Mikkusu (aka JT-02) hybrid persimmon trees at both Matt Renkoski's persimmon farm and also Cliff England's persimmon farm. Pollinated fruits will develop over the summer of 2023, and in the fall, hybrid seed will be harvested and prepared for stratification. The breeding cycle will be repeated in 2024 to generate a second round of seed.

Although I live in the NC-SARE region, and our project is based in the NC-SARE region, I am asking permission to cooperate with two individuals: Matt Renkoski from Missouri and Cliff England from Kentucky. I will explain. The breeding goals of this project is very specific, and to meet the goals, I MUST have access to a specific hybrid genotype for breeding purposes: namely the Mikkusu (aka JT-02) hybrid already mentioned. This is the ONLY cultivar I am aware of which will meet the genetic constraints required for the project. The Mikkusu hybrid has indeed been planted within the NC-SARE region, but only in very small quantities. I have not been able to locate enough JT-02 trees within the NC-SARE region to complete the project. This is why I also intend to cooperate with Cliff England of Kentucky.

I will reiterate the project objectives.

• Generate anywhere from 200-1000 persimmons seeds from a cross of Mikkusu x non-astringent with the goal of developing a non-astringent, cold-hardy hybrid persimmon variety.
• Increase awareness of persimmons as a fruit crop well suited to the southern NC-SARE region and beyond through social media and a progress report published in Pomona (the journal of North American Fruit Explorers).
• Empower prospective persimmon breeders by hosting a persimmon-breeders' virtual workshop through North American Fruit Explorers. The workshop will be recorded and made available as a digital resource.