winning the battle against under skin browning - presentation from the darwin mango field day
TRANSCRIPT
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Winning the battle against under-skin browning
Peter Hofman, Gavin Scurr, Ted Winston, Daryl Joyce, Andrew Macnish, PhD students
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USB on ‘Honey Gold’
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USB affected area
USB - under the microscope
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KP
R2E2?
USB on other cultivars
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Slower fruit cooling rates
Date
Mon 25 Tues 26 Wednes 27 Thurs 28
Tem
perature (o C)
10
15
20
25
30
Trt 1: tight stackTrt 2: air stackTrt 3: wrapped stack
10% affected
34% affected
52% affected
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Physical injury during harvest and transport
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Packaging/transport damage
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Reducing transport damage - packaging
Treatment (packaging)
Inc
ide
nc
e o
f fr
uit
wit
h U
SB
(%
)
0
10
20
30
40
50 Liner (no transport)LinerLiner+wrap (fruit)Liner + sock (fruit)Wrap+pad (tray)
Fruit with any USB Fruit with USB > 3cm2
a
a
bb
bb
b
c
bc
c
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USB test
The breakthrough• Lightly abrade fruit
with sandpaper• Hold at about 13°C
for at least 6 days• Ripen
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Long term focus• How to produce a more robust fruit
• Harvesting• Nutrition• Irrigation• Rootstocks
Under skin browning
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Harvest time
2 am 6 am 10 am 2 pm 6 pm 10 pm
% of fruit w
ith US
B>1 cm
2
10
20
30
40
50
60
70
80
average of no and 1 day delay
Harvested every 4 hrs, cooled immediately or after 1 dUSB associated with abraded sites
Under skin browning – diurnal effects
Similar diurnal effects on USB not associated with abrasion
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Field treatment
Control P 200 g /tree
P 400 g /treeDouble bio gypsum
Percentage
0
10
20
30
40
50
60% abrasion sites with USB
% of f riut with USB>1 cm2 around abrasion sites
% of f ruit with USB>1 cm2 not associated with abrasion
Ca reduced USB around abrasion sites and at other positions on the fruit
Under skin browning – Ca/P
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Recommendations• Reduce physical damage
– Harvest and pack carefully– Use soft liners– Reduce transport vibration/damage
• Delay cooling for at least one day• Hold above 14-16ºC
Producing more robust fruit• Harvest fruit at night
“Watch this space”• Nutrition – calcium• Irrigation
Under skin browning – so far
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Acknowledgements and thanks
Funding• Pinata Farms• Horticulture Innovation Australia
• MG10009 and MG13016
• Dept Agriculture and Fisheries Qld• University of Queensland