Volume 38 Number 2 Article 2 Pages: 37-39
Year 1984 Month 4
Title: Biannual Peaches in the Tropics
Authors: W.B. Sherman and P.M. Lyrene
Citation
Abstract:
The normal growth pattern of highlatitude,
temperate zone peaches is
such that shortening of daylength in
late summer initiates mechanisms that
cause the plant to stop growth well
before the first killing frosts of autumn.
Photoperiod regulates both
flower bud formation and cessation of
vegetative growth, the latter of which
is the first stage of cold acclimation.
This early stage of dormancy may be
reversible in that trees not induced
into deeper dormancy by cold weather may not have built up a full load
of growth inhibitors, and thus may not
need as much or any cold to overcome
the dormancy inhibitors.
In fact, observations have shown that peach cultivars
induced into deep dormancy require more hours of chilling to break
dormancy than those induced only
into shallow dormancy.
The second
stage of acclimation requires low temperatures for induction and is not as
reversible unless a certain amount of
chilling is accumulated.
Temperate
zone peach trees have evolved rest
period chilling requirements to keep
them dormant during winters with
temperatures fluctuating between severe freezes and warm periods which
might induce growth.
In peaches
adapted to low latitudes, chilling requirement is not only reduced, but our
hypothesis is that response to shortening daylength in late summer is also
reduced so that trees tend to grow as
long as temperatures and soil moisture
are favorable.
In addition, flower bud
formation continues with vegetative
growth.
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