This is a final research report from Hort Innovation’s historical archives. Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.

What was it all about?

The National Citrus Scion Breeding Program was a long-term program that was supported by the Australian Citrus Industry since 1991 through a series of discreet projects funded by Hort Innovation (which was then Horticulture Australia Limited) and the research providers CSIRO Plant Industry and Agri-Science Queensland DEEDI. Since 1996 the program had been funded as a fully coordinated project and since 2004 the research had focused in three main areas of activity, namely conventional diploid hybridisation (CSIRO Plant Industry, Merbein), the production of triploid hybrids for seedlessness (Agri-Science Queensland DEEDI, Bundaberg), and mutation breeding (Merbein and Bundaberg).

The development of new scion varieties through breeding, selection and introduction was a high priority for the Australian Citrus Industry. The National Citrus Scion Breeding Program was focused to address industry priorities for new fresh fruit varieties. Major characteristics targeted were seedlessness, easy peel, flavour and size, internal and external quality, and agronomic characteristics such as ease-of-harvest, amongst others. The breeding program aimed to produce new varieties adapted to Australia's varied regional conditions and the research had been designed to provide marketing, processing and production advantages to the Australian Citrus Industry.

Key outcomes of the program were the adoption of innovative new varieties that addressed the needs of key industry-identified market windows of opportunity resulting in increased profitability for Australian citrus growers. Key windows of opportunity identified during the program’s development were for early and late maturing, seedless, sweet, easy-to-peel varieties primarily for export.

Research conducted in project CT07000 produced results that had application to industry in the form of new varieties, as well as having immediate application to the breeding program itself in the generation of better parent material and genetic information. Two new varieties (Merbeingold 2336 and Merbeingold 2350) were released from the conventional diploid breeding component of the program while a new triploid, which was developed from research started before the then Horticulture Australia Limited funding contributed to the resourcing of the program, was established in commercial plantings in Queensland. Many other promising selections, combining seedlessness or low seed numbers, attractive internal and external appearance and high eating quality, were identified and daughter trees were being evaluated in a range of locations. These selections were derived through diploid, triploid and mutation breeding initiatives. Of particular note were three selections from the mutation breeding program (two low-seeded Kara mandarins from Merbein and a low-seeded Fremont from Bundaberg) that were in the process of being entered into large scale semi-commercial trials with industry cooperators.

With the withdrawal by CSIRO from citrus research, including breeding, the future of the program needed to be reviewed by industry. Regardless of this, the program was in a healthy position and it was anticipated that further R&D would see more varieties nominated for release to industry due to improved germplasm that would underpin an Australian citrus breeding program into the future and so was likely to address the goals documented in the breeding plan.