Agriculture Reference
In-Depth Information
been reported for 'Delicious', 'Golden Delicious', 'McIntosh' and 'Spartan'
(Bangerth,
; Williams,
; Bramlage
et al.
,
a; Autio and Bramlage,
).
Diazocyclopentadiene (DACP) is a light-activated compound thought to
inhibit ethylene binding. Applied to mature, pre-climacteric 'Red Delicious'
apples, it results in lower internal ethylene concentration whether the fruits
are kept at
◦
Cor
◦
C. At
◦
C untreated apples had a flesh firmness of
N.
DACP-treated fruits also retained their firmness much better than controls
when stored at
newtons after
days, DACP-treated apples a flesh firmness of about
◦
C (Blankenship and Sisler,
).
Treatments during post-harvest storage so as to maintain internal ethylene
levels below
.
ppm inhibit the onset of softening, delaying this by about
-
weeks(Stow
et al.
,
).Earlierstudies(Smock,
;Forsyth
et al.
,
;
Knee and Hatfield,
) had also shown ethylene removal during storage to
aid in retention of firmness.
Ethylene is also involved in the development of the post-harvest disorder
knownassuperficialscald.Thisischaracterizedbyirregularshapedtantodark
brown blotches on the fruit skin. It is the most serious post-harvest disorder of
many cultivars although some are highly resistant (Lau,
). Scald is thought
to result from the oxidation of
-farnesene in fruit surface waxinto conjugated
trienes which cause injury to the epidermal cells. Removing ethylene during
storage delays the production of
α
-farnesene and reduces the concentrations
of its oxidation products and the development of scald (Knee and Hatfield,
α
).
There are some indications that inadequate ethylene concentrations may
inhibit aroma production (Song and Bangerth,
; Knee,
; Dover,
).
Control of ethylene
Control of fruit quality can be effected through the control of synthesis, accu-
mulation or action of ethylene or by combinations of these.
For climacteric apples and pears control is much more likely to succeed at
the pre-climacteric stage before the large increase in ethylene concentration
due to autocatalytic production occurs.
Synthesis rates increase as the fruits mature. Synthesis rates can be modified
by chemical treatments in the orchard and by the use of high CO
treatment
after harvest. They are also dependent on oxygen and temperature levels and
vary greatly between cultivars.
AVG inhibits ACC synthase. Its application in the orchard a month before
the expected date of harvest of 'Cox' apples reduces the ethylene concentration
