Agriculture Reference
In-Depth Information
fruit
fruit
fruit
8
+--
+
--
+
--
6
4
2
2
4
August
September
October
Figure 8.9
Effect of defruiting [either] in August,September or
October on net photosynthesis and dark respiration of 'Golden
Delicious' apple trees. Each column represents the mean of
continuous measurements over 5 days prior to (left columns) or after
fruit removal. From Wibbe and Blanke (1995). Reproduced with
permission.
Effects of fruiting
Wibbe
et al.
(
) found that fruiting trees had
much higher net photosynthesis from June to October inclusive and higher
dark respiration from June to September inclusive, than trees without fruits
(Figure
) and Wibbe and Blanke (
). The parallel effects on net photosynthesis and on dark respiration
may have been attributable to defruiting effects on stomatal behaviour, since
dark respiration largely depends on stomatal aperture. Defruiting increased
netrespirationinOctoberandhadaverynegativeeffectonNCER,whichmay
be associated with earlier leaf senescence and translocation of carbohydrates
for storage in de-fruited trees.
Wunsche and Palmer (
.
b) found that fruiting may not affect NCE early
in the season, presumably because of compensatory shoot and leaf growth
on the trees with few or no fruits. As shoot and leaf growth ceased the sink
strength effect of fruits was evidenced by higher CO
uptake by fruiting than
non-fruiting trees.
Source-sink relationships and
carbohydrate partitioning
In many annual crop plants the greatest gains in economic yield have
been achieved by breeding and selection of cultivars which direct a greater
