Golden Ava apples - Precision ripening for uniform maturity and improved colour in the Goulburn Valley, 2020
SUNRED and FOLICIST applications pre-harvest improved uniformity of Golden Ava apples
Richard Hall, 18 April 2020
Summary
SUNRED and FOLICIST sprays for precision ripening improved the uniformity of Golden Ava apples at harvest.
Using AgIntelligent® Imaging we measured the green colour from 160 images of 40 apples - top, bottom, exposed side and shaded side of each apple.
We can use apple colour (measured as greenness a*) as a non-destructive indicator of apple maturity.
Materials and Methods
Trial design was determined and implemented by the grower.
SUNRED and FOLICIST was applied commercially in a block of Golden Ava apples in the Goulburn Valley, March 2020.
One end of the block was sprayed (Treated) and the other end unsprayed (Standard).
Standard - March 2020
Timing
Pre-harvest
Foliar
Grower standard - unsprayed
For more information refer the Apple & Pear Program.
Results and Discussion
Apple colour can be used as a non-destructive measure of apple maturity.
AgIntelligent® Imaging measures apple colour in the CIELab colour space. In this colour space, red and green are on the same axis a*. Negative values are green, positive values are red. Measuring increasing greenness with negative numbers can get confusing.
We don't need to get too caught up in the technical detail of colour measurement however, these plots are a good way of visualising the data intuitively.
The key point is - precision ripening gives us uniform maturity > uniform colour > uniform fruit quality
In Figure 1 we see the yield distribution of apples according to their colour - green (a*). This colour is averaged across all the pixels captured in 160 images of the apples - top, bottom, exposed side and shaded side.
To the left, the more negative the numbers and the more green the apple.
To the right, the less negative the numbers and the less green the apple.
We can see the king and lateral fruit at different stages of ripeness and we see the Standard fruit maturity is more spread out compared to the more uniformly ripened Treated fruit.
Figure 1: SUNRED and FOLICIST Treated apples showing more uniform maturity at harvest compared to standard apples. AgIntelligent® Imaging measure of apple greenness (a*). Note red and green are measured on the same axis (a*). More positive numbers are less green (closer to red) and more negative numbers are more green (further from red).
The combination of SUNRED and FOLICIST improves ripening uniformity, promotes optimum colour development (regardless of variety) and protects colour from sunburn and oxidation.
Conclusions
It is recommended to include 2 pre-harvest sprays of SUNRED and FOLICIST for precision ripening and uniform maturity of all apple varieties per the Apple & Pear Program.
Acknowledgments
Thank you to the growers for leaving one end of the block unsprayed and their interest in evaluating this work in the field.
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