Agriculture Reference
In-Depth Information
days after full bloom and mean
fruit weight at harvest on trees subjected to controlled temperature regimes over
Table
.
Mean apple fruit expansion rates
-
-
days
Max/Min temperature (
◦
C)
Cultivar
/
/
/
/
Fruit expansion rate (mm day
−
)
'Delicious'
. d
. c
. b
. a
'Golden Delicious'
. d
. c
. b
. a
'Fuji'
. d
. c
. b
. a
Harvest fruit weight (g)
'Delicious'
b
b
a
a
'Golden Delicious'
b
b
a
a
'Fuji'
Figures with different letters within rows significantly different at
P
≤
.
.
◦
/
◦
C were commercially mature.
All fruits harvested when those at
From Warrington
et al.
(
). Reproduced with permission.
thinning agents (see p.
), and carbaryl and cytokinins are used (Wertheim,
).
In many traditional fruit-growing areas apple and pear fruits tend to be smaller
in cooler than in average seasons, or when grown under cool conditions by
reason of latitude or altitude. Controlled environment studies have shown
that temperatures early in the season, from
days after full bloom,
have a major controlling effect on fruit growth rates and on fruit weight at
maturity (Table
to
simulated nat-
ural diurnal patterns with temperature maxima and minima ranging from
◦
/
.
). The temperature regimes in Table
.
◦
C)
regimes were more adverse and more favourable for fruit growth, respectively
(Warrington
et al.
,
◦
Cto
◦
/
◦
C, in other trials cooler (
◦
/
◦
C) and warmer (
◦
/
). Similar temperature regimes over the period from
to
daysafterfullbloomshowedmuchsmallerandlessconsistenteffects.This
isconsistentwiththemajoreffectoftemperaturesinthisrangebeingonthecell
division process which is usually largely complete by
days after full bloom.
High night temperatures can be deleterious. Tukey (
,
) found that
◦
C than at
◦
C at night, it was much
although fruit growth was greater at
◦
C than at either of the lower temperatures. Tamura
et al.
(
poorer at
)
◦
C and day temperatures
◦
C
found that keeping night temperatures at
above ambient was stimulatory for the first
weeks after bloom and then was
detrimental so that by
days the fruits were of the same size. The fruit
growth stimulation was due to increased early cell division, which ended
-
-
days earlier than in the controls to give the same final cell number.
