By Dr Tahir Khurshid, NSW DPIRD, Dareton

This article summarises the project activities for the National persimmon varietal evaluation program – PR17000.

This project was started in late 2018 and completed in July 2023.

The project achieved it objectives as per project proposal and progressed through a range of activities despite COVID-19.

The national persimmon varietal and rootstock evaluation program of Australia is a multi-stage process involving negotiations with overseas collaborators, importing varieties and rootstocks, post-quarantine entry requirements (PEQ), the release of trees from quarantine, establishing source trees, tree propagation post-PEQ, and establishing field trials followed by the evaluation and recommendation processes.

The project was focused on:

1. Importing early maturing varieties and rootstocks from overseas.
2. The genetic verification of the ‘Rojo Brillante’ variety.
3. Establishing trials for the existing varieties at NSW DPI Dareton Research Station.
4. Developing a clonal propagation method to produce rootstock seedlings for the tree uniformity trials.

During the project, strong collaboration was established with scientists and persimmon breeders from Spain, Japan, South Korea and China.

The momentum of collaboration was maintained despite the hurdles of COVID-19 and the fact a personal visit to these countries was not possible for three years.

The Australian persimmon industry is dependent on the early maturing varieties from overseas.

Therefore, significant efforts were made during this project to import the ‘Taishu’ variety from the University of Miyazaki, Japan (Figures 1 & 2).

Since the variety has been in Australia, a budwood mother block will be established and buds will be available to growers in the next few years.

The early maturing variety from South Korea will arrive in Australia in coming years.

The process of importing varieties from South Korea was delayed due to COVID-19, and also due to the difference in growing seasons as compared to Australia.

However, this process will now be expedited.

True-to-type genetic verification of the Spanish ‘Rojo Brillante’ variety was required to confirm its originality.

The genetic work was carried out in collaboration with the Spanish breeder Dr Maria Badenes.

The DNA of ‘Rojo Brillante’ was extracted and compared to the original genetic markers in Spain.

Phenotypic verification was also carried out to confirm the external appearance, shape, and internal quality characteristics during her visit to Australia in 2019.

Subsequently, the budwood blocks were established at Dareton, and the budwood are now available to growers from September 2023.

The Diospyros lotus rootstock was also imported from Spain. Rootstock seedlings were raised and grafted with ‘Jiro’, ‘Fuyu’ and ‘Rojo Brillante’ for evaluation purposes.

Genetic work was carried out with a Spanish collaborator to identify the male and female trees, and the results were shared with Australia.

After the verification, male and female trees were planted to establish the seed source for Diospyros lotus at Dareton (Figure 3), an activity which took five years to be completed.

A replicated site for the Diospyros lotus was also established at a grower’s property in NSW as a backup.

Australian growers now have access to the budwood of male and female Diospyros lotus from Dareton, which could help them establish their own seed source for Diospyros lotus.

One of the project's objectives was to establish a trial site with a range of existing and new varieties at Dareton.

Those varieties will be used for future evaluation to determine if there are any early maturing varieties.

Eleven scion varieties and two rootstocks are now established at Dareton.

Some of these varieties will be evaluated for maturity (early or late), yield, quality, and physical disorders in near future.

Australian persimmon orchards have issues with tree uniformity, which results in poor tree performance and yield.

Tree uniformity is due to the genetic variability in rootstock seeds.

Some seedlings can have poor and stunted growth, which becomes prominent a few years after planting.

Other reasons for the lack of uniformity could be poor rootstock seedlings or disease in the rootstock at the nursery level. Therefore, a clonal propagation technique was developed during this project to produce rootstock seedlings.

Two clonal propagation methods, tissue culture and single node cutting technique, were used to produce rootstock seedlings.

The same genetic material was used from one healthy source tree, and many uniform (true-to-type) rootstocks were produced. Agromillora Nursery helped with the tissue culture work.

The rootstock seedlings were successfully produced by the tissue culture method following the acclimatisation and hardening protocols.

These seedlings have been recently budded to ‘Jiro’ and ‘Fuyu’ varieties.

The next step is to plant the new trees and to test the uniformity of trees.

This work will continue into the current project.

Seedlings were also produced from the single node cutting technique.

Several experiments were conducted over 4 years using cuttings collected at different growth stages with different levels of growth regulators applied at the base of the cutting using different potting media.

We concluded the technique was slow and laborious and produced only a few seedlings and was not recommended for commercial operations.

The recommendation was to use the tissue culture technique, which is rapid, and a large number of seedlings can be prepared for the benefit of the persimmon industry.

The previous project initiated different research activities, and these will be completed in new project (PR23000) which has been funded until 2029.

The new project will continue to assess the tissue culture produced rootstocks for Diospyros Kaki.

Trees’ uniformity of tissue cultured produced rootstocks will be assessed in coming years.

New early maturing varieties from overseas countries will be imported to Australia to evaluate the earliest and production under the Australian conditions.

De-astringency work on astringent type Spanish variety ‘Rojo Brillante’ will be carried out followed by their performance in storage trials (Figure 4).

It is expected growers will be producing ‘Rojo Brillante’ in their orchards in coming years – there are a few growers who have already planted 4000 trees of the ‘Rojo Brillante’ variety.

The ‘Rojo Brillante’ budwood has been provided by NSW DPIRD (Department of Primary Industries and Regional Development) Dareton to growers and nursery men since August 2024.

This project will produce a series of articles about the ongoing progress outputs and its implementation for the persimmon growers.

This project has been funded by Hort Innovation, using the Hort Innovation Persimmon Fund research and development levy, co-investment from NSW Department of Primary Industries and Regional Development, and contributions from the Australian Government.