Tropical stonefruit breeding and evaluation

What was it all about?

From 2014 to 2021, this investment ran a targeted breeding program to develop and evaluate new low chill stonefruit varieties with improved production characteristics. Low chill stonefruit quality is essential to the broader stonefruit industry as it sets the standard for the start of the domestic season. Low chill stonefruit ripens from September to November, and industry has identified breeding more profitable cultivars as a high research priority.

The research team used controlled cross-pollination to combine selected parents, and nearly 7,000 seeds were germinated. Over 2,600 seedling trees were planted in progeny field trials at the Maroochy Research Facility in Nambour, Queensland. Seventy-one elite genotypes were selected and evaluated for chilling requirement, crop load and tree size. The research team assessed the fruit for size, colour, soluble solid content, flavour, firmness, texture, stone freedom, skin bitterness and ripening time.

The elite selections were propagated for further testing at Maroochy Research Facility and grower trial sites. Of the 428 evaluations performed during the project, 64 per cent were on peach, 33 per cent were on nectarine, and 3 per cent were on other species, including plum, apricot and interspecific hybrids. 

Sixty elite peach, nectarine and plum selections were distributed for grower evaluation at 11 locations as part of the small-scale testing. The project team evaluated the performance of these trees at field days and annual meetings of Low Chill Australia (a voluntary organisation for low-chill stonefruit growers). 

SF1300These tests identified 11 selections of peach and nectarines that were released for large-scale evaluation, resulting in 3,829 trees planted at 13 sites. Two selections (Q17-20 peach and Q32-59 nectarine) have been widely planted and have part 1 Plant Breeders Rights.

A further three low-chill selections ripening in the early season and with novel fruit characteristics, including a flat or “Peento” peach, a flat nectarine and an all-yellow peach, were also protected by Plant Breeders Rights. An all-yellow nectarine marketed as “Nectacot” remains to be Plant Breeders Rights protected.

To increase the diversity of the breeding population, the research team sought new sources of germplasm and developed traits that are not common in commercial cultivars. The Mexican landrace peach “Nieve” was used to establish trees with all-white fruit and altered tree architecture. Feral peaches were collected from the subtropical regions of Queensland and New South Wales. The stony-hard flesh texture trait was introgressed from Korean germplasm and offers the potential to reduce harvest costs by reducing the duration of fruit ripening.

Elite selections distributed to growers in the past four years have not been thoroughly evaluated. These have been planted at 11 locations across four states and protected by material transfer agreements.