Rain-induced fruit cracking in sweet cherry (Prunus avium L.).
Measham, P (2011) Rain-induced fruit cracking in sweet cherry (Prunus avium L.). PhD thesis, University of Tasmania.
Production of sweet cherries (Prunus avium L.) around the world is centred on
achieving high quality, blemish free fruit. One of the main concerns to Australian
cherry growers and limitations to production is the unpredictable nature of raininduced
fruit cracking, which occurs in the later stages of fruit development and
renders fruit unsaleable in markets that attract premium fruit prices. Control of
cracking remains unreliable and the underlying mechanism is not yet fully
understood. This thesis examines cracking from a tree water relations perspective,
starting with patterns of crack development, the relationship of rainfall and fruit
properties with cracking incidence, and concludes with an exploration of the
underlying mechanisms resulting in crack development.
Cracking takes three distinct forms; stem end cuticular fractures, apical end
cuticular fractures and large cracks, usually deep into the pulp, on the cheek of the
fruit. This study has demonstrated that although all three types developed in the
three-week period prior to commercial harvest, varieties displayed different levels
of total cracking and distinctly different proportions of each crack type. Overall
the extent of cracking was strongly controlled by season. While initial
development of cracks coincided with rainfall, no relationship between amount of
rain and incidence of cracking was found. There were also relationships between
both crop load and tangential stress of the fruit skin with crack type and incidence.
Influx of water to the fruit via the vascular system was recorded after rainfall,
prompting an investigation of the influence of water uptake both via the vascular
system and directly across the skin. Application of excess water to simulate rainfall, only to the root-zone induced large cracks in the side of the fruit.
Application of water at a similar rate to the canopy induced cuticular cracks
localised around the stem and apical end of the fruit with no increase in deep side
cracks. This finding suggested different water uptake mechanisms driving
development of side cracks and the shallower cuticular cracks at the ends of the
fruit. An exploration of the driving forces responsible for vascular entry of excess
water into the fruit proposed influx via the pedicel phloem and supported a role
for adjacent leaves in control of water movement under conditions likely to
initiate deep side cracks.
The findings establish mode of water uptake into the fruit as the main determinant
of crack type in a susceptible variety. Future management of cracking needs to
consider both varietal and seasonal factors, and may need to be variety or crack
|Item Type:||Thesis (PhD)|
|Additional Information:||Copyright © the Author -
The publishers of the papers compromising Chapters 4 and 5 hold the copyright
for that content. |
|Keywords:||cherry, cracking, cuticular, vascular|
|Deposited By:||ePrints Officer|
|Deposited On:||03 Sep 2011 13:57|
|Last Modified:||11 Dec 2012 14:34|
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