Agriculture Reference
In-Depth Information
Table
.
Effect of application of
.
% hydrogen cyanamide in
,
,
on cropping efficiency (accumulated yield per cross-section of trunk), the
calculated reduction in cropping efficiency as a result of inadequate winter chilling, and
the averaged date of full bloom
and
-
Accumulated yield (kg) per trunk
% cropping
Average
cross-sectional area (cm
)
efficiency
date of
deficit
full bloom
Cyanamide
Unsprayed
(T
−
U)/T
(days from
Cultivar
treated (T)
(U)
August)
'Goldjon'
.
.
'Mutsu'
.
.
'Mollies
Delicious'
.
.
'Canvada'
.
.
'Drakenstein'
.
.
'Golden
Delicious'
.
.
'NJ '
.
.
'Marjorie Pye'
.
.
'Spartan'
.
.
'Starking'
.
.
'Granny Smith'
.
.
'Ohinemuri'
.
.
Correlation between increases in accumulated yield in response to cyanamide (%)
and date of full bloom
r
=
.
∗∗∗
R
=
.
Correlation between cropping efficiency deficit and date of full bloom
r
=
.
∗∗∗
R
=
.
From Jackson and Bepete (
). Reproduced with permission.
reported that cambial activity in apples and pears resumes early in April
when cells at the outer margin of the cambial zone begin to differentiate
into phloem sieve elements. Later, in mid-May, xylem and sclereid differ-
entiation begins. The differentiation of new conducting tissue below the
buds prior to budburst is obviously dependent on the use of carbohydrate
reserves.
The initial stages of new shoot extension growth after budbreak are also
dependent on the use of reserves of carbohydrates, nitrogen and other min-
eral elements. Hansen (
) estimated that half to two thirds of the building
materials used in spurs until the flowers show colour, and in extension shoots
up to the five- or six-leaf stage, come from reserves. The main source of the re-
serves of carbohydrates appears to be the root system (Quinlan,
; Hansen
and Grauslund,
), while confirming the importance
of carbohydrates from the root, considered that the whole perennial structure
), but Kandiah (
