Agriculture Reference
In-Depth Information
% of the utilized pear production was for the fresh market, the proportion
being greater in the more recent years. 'Bartlett' used in processing, mainly
grown under contract for canning, averaged about
% of the 'grower price' of
'Bartlett' for fresh consumption in the USA over the years
.
Processed pears of other cultivars tend to be used in juice and other low
value products and achieved only about
and
-
% of their fresh fruit price (Belrose,
).
Climatic conditions in major centres
of production
It is clearly impossible to give any narrow description of the climatic conditions
required for successful apple and pear production. Apples and pears are grown
for export, i.e. to an internationally competitive level, in climates as diverse as
those of the Netherlands and South Africa. They can be grown with varying
degrees of success throughout the temperate zone and, increasingly, in the
subtropics and even the tropics. Successful production depends both on the
climate, especially the local microclimate, and on effective adaptations to this
in terms of cultivar selection and cultural practice. This is discussed in detail
later.
Table
illustrates the range of temperatures in which apples and pears are
successfully produced. The dominant climatic constraints range from winter-
freeze damage in Poland to inadequate winter chilling for fruit bud develop-
ment of most cultivars in Egypt, and summer heat stress and fruit sunburn
in Washington State. It should be noted that whereas the means of the daily
minima and maxima (daily means) are useful in defining growing conditions,
the means of the monthly minima and maxima (monthly means) are much
more informative as the levels of potentially limiting stress factors which occur
on a regular basis.
At a more subtle level, temperature effects on fruit set, fruit size, fruit colour
and fruit shape determine where the leading apple cultivar, 'Red Delicious',
is best produced.
Table
.
shows the incoming solar irradiation in a number of apple and
pear growing regions. At higher irradiation levels a greater depth of canopy
can receive light at any given level so potential photosynthesis of the canopy
is increased.
Irrigation is practised in most of the major regions of apple and pear produc-
tion. Rainfall is probably adverse in most areas, leading to increased incidence
of fungal diseases, especially apple scab, and bacterial diseases, especially fire
blight, on pears. The high cloud cover associated with rainfall is also a major
factor in reducing the available solar radiation in many fruit-growing areas.
.
