Low-chill stonefruit cultivar breeding and evaluation (SF07003)

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Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.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?

Peaches and nectarines grown in subtropical Australia were called low-chill stonefruit. They required only a small number of cold nights each winter to break dormancy which allowed them to thrive in the subtropics. Low-chill stonefruit were mostly grown in northern NSW and southern QLD. They produced peaches and nectarines that were fully ripe in September and October, well before there were any other Australian stonefruit available for consumers. The low-chill sector of the Australian stonefruit industry produced peaches, nectarines and plums with an annual wholesale value of $35M at the time.

Low-chill stonefruit quality was of high importance to the wider national industry as it set the standard for the start of the domestic season. Consumers purchasing high quality low-chill peaches in October and November continued purchasing high-chill peaches during summer. Conversely, consumers did not purchase high-chill fruit if they had bad experiences with low-chill varieties. In the future, low-chill cultivars were likely to have had direct benefit in temperate regions of Australia that were affected by global warming.

The low-chill peach breeding program was located at Nambour in Queensland and was initiated in 2001 in response to industry requests for new peach and nectarine cultivars adapted to subtropical Australia. The program developed a range of high quality peach and nectarine cultivars that were expected to grow well in subtropical Australian conditions.

From 2007-2013, over 10,000 new peach and nectarine trees were field planted at Nambour and evaluated for fruit and tree traits. Fruit characteristics selected were large size, high flavour, firm flesh and early ripening. Tree characteristics selected were low chilling requirement, moderate crop load and compact tree habit. The researcher selected 64 elite trees and these were sent for grower testing.

Growers played a major role in the breeding program through their involvement in a two-stage grower testing scheme. The first stage was a small-scale test in which a limited number of grower co-operators received and evaluated a large number of selections. Results from this testing were used to define the very best selections. The second stage was a large-scale test in which the elite selections were made available to any grower in Australia who agreed to participate in the scheme. A total of 64 selections were sent for testing in the small-scale scheme during this project. A total of 16 elite selections and 21,796 trees were released to industry for the large-scale testing from 2007 to 2013. Three selections from this breeding program were currently in a Plant Breeders Rights trial.

Industry and researchers were informed of the results from this project through 16 industry meetings and field days, 5 local, national and international conferences and the publication of 26 articles in grower magazines and scientific journals. The most significant extension results occurred from the close liaison between the project team and voluntary grower organisation Low Chill Australia Inc.

The breeding project developed a strong base of new peach and nectarine varieties for use by the low-chill stonefruit industry. This material assumed greater national significance if winter temperatures in southern states increase. A new 5-year breeding project was submitted to Hort Innovation (which was then Horticulture Australia Limited) in which low-chill varieties would be further developed and more superior cultivars released to industry.