Breeding citrus varieties for growers and consumers

Investments to ensure access to superior citrus scion and rootstock varieties

The investment Evaluation of new citrus varieties 2017-2022 (CT17006) is carrying on the work to assess new citrus varieties rapidly and independently under local conditions – providing industry with objective performance data. It is a continuation of earlier levy investments, including the project Evaluating new citrus varieties 2013-17 (CT12026).

Knowledge from the evaluation work is brought to growers through field walks, fruit variety displays and other industry events, while information sheets describing the horticultural performance of all varieties evaluated are also produced.

The major site for the evaluations is at the NSW Department of Primary Industries’ Dareton Research Station site and two satellite sites in WA covering soil types and some climatic conditions of major citrus production regions. Kevin Lacey from Department of Primary Industries and Regional Development is one of the team lead by NSW DPI Institute Director, Dr David Monks.

The Hort Innovation Citrus Strategic Investment Plan has prioritised ensuring access to superior scion and rootstock varieties for efficient production that matches consumer quality expectations. This project is one of four recent investments contributing towards this outcome, including:

• Building a genetic foundation for Australia’s citrus future through targeted breeding (CT15017)
• Evaluation of new rootstocks for the Australian citrus industry 2017-2022 (CT17002)
• Breeding new rootstocks for the Australian citrus industry (CT18004)

A strategic review of investments in citrus breeding and evaluation found the program of four projects was on track to have at least 20 varieties and rootstocks evaluated for Australian conditions and accessible to growers. A key aspect of the program has been working with industry representatives on the Citrus Australia Variety & Rootstock Committee to prioritise key variety traits of interest to evaluate for the Australian citrus industry.

Meet Shane Kay, CEO of Moora Citrus in Perth, WA

One of WA’s largest citrus orchards, Moora Citrus is 250km north of Perth. There is a mix of oranges and mandarins in the sandy soils with temperate conditions, and relative hot summers compared to other growing regions. It is one of the sites in WA where the variety evaluations are planted.

Why is this project important?

“Evaluation of varieties is critical for choosing the next variety to plant. Any new planting is a big outlay upfront, so you want to have some confidence what you’re planting is going to do well in the Australian conditions.

A classic example is we had some beautiful mandarins that grew well in our conditions and had good yields, so we were happy to grow them. But the buyers wanted mandarins without seeds so we had to go looking for a variety that could grow just as well, but without the seeds and was easy-peel.

The difference in how the varieties grow and perform in different locations has also come through from the program. Clementine mandarins grow really well here in WA but not so well in other places.

For our export market we want to target the window where there isn’t fruit from other countries or that has a unique characteristic that means they buy our fruit over the competition. We found there was a gap in the supply window for late season navels and so our orchard looked at the variety that could be grown to supply that late window, did well in our growing conditions and lasted the journey to export markets.

The increasing demand by domestic and international consumers for seedless varieties, easy-peel mandarins and oranges meeting specific supply windows has seen a move away from or expansion on traditional varieties. They also need to be able to withstand the cold treatment required for export protocols. For the growers this means being able to grow them in their region, looking for yields, cost effective management and more recently tolerance to exotic pest threats not currently in Australia such as Huánglóngbìng (HLB).

What future benefits will this project bring?

“These new varieties when combined with appropriate rootstocks also generate higher, more consistent yields and better packouts than traditional varieties. 

39 per cent of current plantings in WA are of varieties that have been through the evaluation program. The introduction of the Afourer mandarin variety has had a major impact on mandarin production. Anecdotal information indicates that compared to traditional varieties such as Ellendale, Hickson and Emperor, the Afourer variety generated a 30 per cent price premium initially and increased yields by up to 30 per cent at maturity.

Over five years this project rapidly and independently assesses new citrus varieties under local conditions. Varieties cross the citrus category range – including Valencia oranges, mandarins, navels, lemons and grapefruit. Three mandarins from Florida were also included in the program in November 2020, with grafted trees to be planted as they come up to size. These varieties claim to have HLB tolerance and may form part of Australia’s defence against this disease.”

Evaluation of varieties is critical for choosing the next variety to plant. Any new planting is a big outlay upfront, so you want to have some confidence what you’re planting is going to do well in the Australian conditions.” Shane Kay, citrus grower