Advancing hull split to maximise yield and quality of walnuts (WN09000)

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Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.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 Australian walnut industry is undergoing rapid expansion with the potential to supply high quality nuts to local and export markets. Optimizing the quality of nuts is essential to maximise these opportunities. Major factors that determine nut quality are the colour of the edible kernel and whether the shell of the nut is clean and undamaged.

Thus, research was conducted to investigate factors that affect nut quality and to help walnut growers determine when walnuts are ready to be harvested.

In a preliminary study to determine when nuts are nearing harvest, the timing of kernel maturity was similar for cultivars Howard, Lara and Vina in NSW, whereas Lara kernels matured earlier than Vina kernels in Tasmania. In NSW, the progression of hull maturity was sooner in Vina than Lara, whereas in Tasmania the progression of these cultivars was similar. A possible reason why these cultivars matured differently may have been the variation in climate between growing regions. Future research should provide further insight into the nature of these events.