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Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.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 papaya breeding and varietal development project moved the industry significantly towards its objective of producing varieties with excellent flavour and appearance as well as good agronomic characteristics. Incremental improvements in fruit and plant characteristics had been achieved through recurrent selection using a breeding population based on parents with broad genetic variation.

The validation of the program design had been confirmed by investigation into general or specific combining ability of a range of genetic traits. The breeding strategy of incremental improvement, which had been adopted, was most applicable for papaya breeding. The strategy of using highly self-pollinated male lines and relying on specific trait combinations was not suitable for papaya breeding.

Through this program, the close relationship between musk flavour and winter spot had been broken so that new varieties with the desirable traits of fruit flavour and sweetness now also have reduced levels of winter spot.

Improved methodologies in assessment techniques and data collection provided the groundwork to reduce future breeding costs. Similarly with the micro-propagation techniques, the laboratory turn around time had been significantly reduced due to improved practices. This was despite a major breakdown to the tissue culture laboratory at a critical stage through the project.

The benefits of micro-propagated plants over conventional seedling plants were demonstrated to industry.

The industry was encouraged to field evaluate the selected varieties form the last random cross population and move to the third crossing population.