Agriculture Reference
In-Depth Information
in the apples at harvest and over several months of storage at
.
%O
,
<
◦
C. The fruits are appreciably firmer than controls af-
ter storage ( Johnson,
%CO
and
.
).
Daminozide, which is no longer used, was also effective in delaying the
onset of high ethylene production although it has no effect on ACC synthesis
and the mechanism of its effect is uncertain (Knee,
). Its use pre-harvest
resulted in firmer apples after storage under controlled atmosphere conditions
with ethylene removal (Liu,
).
Treatment with
%CO
for
-
days after harvest prior to storage at
◦
Cin
.
.
%O
/
<
%CO
delays the autocatalytic production of ethylene
(Knee and Stow,
). High CO
treatment helps retain firmness in store if
combined with removal of ethylene (Stow,
).
Oxygen is required for the conversion of ACC to ethylene and ethylene
production in store is reduced as the O
content is reduced from
%to
%
◦
to
◦
C ( Johnson and Ertan,
to
).
Ethylene production by 'Cox' and 'Bramley' apples in both pre-climacteric
and post-climacteric states declines with declining temperature with a Q
value of about
% at temperatures from
).
Differences in ethylene production between cultivars may reflect differences
in stage of maturity at harvest, for example 'Bramley's Seedling' is usually har-
vested much earlier relative to its climacteric than is 'Cox'. They may also be
intrinsic. Blanpied
et al.
(
(Knee,
) contrasted 'McIntosh' as a rapid ethylene pro-
ducer with 'Empire' as a slow ethylene producer, and Jobling and McGlasson
(
) found 'Fuji' to have a maximum rate of ethylene production only one
hundredth of that of 'Gala', which may be associated with its maintenance of
flesh firmness. Knee (
◦
C with continuous
) noted that in
%O
at
.
ethylene removal 'Crispin' ('Mutsu') and 'Gloster
' took more than
days
ll
−
ethylene whereas 'Spartan' took only
to reach
days and other
cultivars were intermediate. The slow production of ethylene by 'Gloster
.
µ
'is
heritable (Stow
et al.
,
). It appears to be caused by enhancement of an in-
hibitory mechanism preventing initiation of autocatalytic ethylene production
rather than lowered activity of a single enzyme in the ethylene biosynthesis
pathway.
Control of accumulation is also a key element in control of synthesis since ac-
cumulation leads to enhanced production. Traditionally great care has been
taken to avoid putting ripe apples with high ethylene production into a store
with pre-climacteric fruits and to ensure good natural ventilation. In virtually
gas-tight stores the internal ethylene concentration in the fruits can be mini-
mized by removal of ethylene from the store atmosphere so that the gradient
from the inside to the outside of the fruit, hence the rate of diffusion out of the
