Agriculture Reference
In-Depth Information
injury is a storage disorder that occurs at temperatures below 12.5°C, the
extent of the injury being dependent upon the storage temperature and
duration: at 0°C injury occurs in 4 days, at 5°C in 8 days and at 10°C in 12
days. The symptoms include skin scald, failure to ripen and increased disease
susceptibility.
Sap burn caused by fruit skin contact with sap exuded from the cut or
broken pedicel reduces consumer acceptance because of the browning and
blackening of the skin after lenticel penetration. The Australian cultivar
'Kensington' is very susceptible (Lovey et al. , 1992), while 'Irwin' is less
susceptible. The sap component in 'Kensington' thought to cause the burn
is the major non-aqueous terpene component, terpinolene; it can also burn
'Irwin', but in 'Irwin' the predominant terpene (6.8%) is car-3-ene. This sap
is present in the latiferous ducts of the fruit and is not interconnected with the
stem ducts. The latex is under some pressure and when the pedicel is broken
can shoot 300 mm or more. Harvesting with the stem attached, draining with
the pedicel down and washing are ef ective.
One fruit disorder, occurring especially in 'Alphonso' in India, is referred
to as 'internal breakdown', 'spongy tissue' or 'soft tissue'. The lower half of the
fruit is most af ected and it may be related to preharvest heat stress. 'Soft nose'
in Florida is serious, with high Ca inhibiting the disorder and high N increasing
the disorder (Malo and Campbell, 1978). The 'jelly-seed' disorder is more
widespread. The disease usually appears during the initial stages of maturity,
with a loss of fi rmness of the pulp near the endocarp, which becomes jelly-like
and translucent with advancing ripeness. The disorder does not develop after
harvest. An open cavity may develop in the pulp at the stem end prior to pulp
breakdown. 'Tommy Atkins' has been reported to be especially susceptible to
this disorder, although 'Kent', 'Irwin', 'Sensation', 'Carabao', 'Alohouron' and
a few other commercial cultivars of importance are also susceptible (Campbell,
1988). No pathogenic organism has been detected. The only recourse for this
disorder is to harvest the fruit at the mature-green stage, before any colour
break occurs on the skin.
Certain cultivars are particularly susceptible to lumpy tissue, which is not
evident in green fruit but develops during ripening. The mesocarp contains
white starchy lumps and the fruit surface develops indentations. Aetiology is
unknown. It has been reported from Thailand and the Philippines. Internal
fruit necrosis fi rst appears as a brown area in the mesocarp and endocarp
of rapidly growing fruit. This later extends to the skin and a brown-black
gummy exudation occurs. These areas then collapse and are surrounded
by corky tissue. This non-pathological disorder has been associated with
boron defi ciency.
 
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