Báo cáo lâm nghiệp: "Correlative control of early stages of flower bud initiation in ’bourse’ shoots of apple (Malus x domestica Borkh. cv. Golden Deliciou"
Chia sẻ: Nguyễn Minh Thắng
| Ngày:
| Loại File: PDF
| Số trang:3
Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Correlative control of early stages of flower bud initiation in ’bourse’ shoots of apple (Malus x domestica Borkh. cv. Golden Delicious)...
Nội dung Text: Báo cáo lâm nghiệp: "Correlative control of early stages of flower bud initiation in ’bourse’ shoots of apple (Malus x domestica Borkh. cv. Golden Deliciou"
Correlative control of early stages of flower bud initiation
in ’bourse’ shoots of apple (Malus x domestica Borkh. cv.
Golden Delicious)
J. Crabbé
J. Escobedo
agronomiques, Gembloux, Belgique
Facult6 des Sciences
Morphog6n6se v6g6tale appliqu6e,
renewed floral induction. There may be
Introduction
year-to-year irregularities due to competi-
at the same site
tion with fruit growing
in fruit
A better of flowering
understanding
(alternate bearing) or with nearby vegeta-
trees would be obtained if we could pre-
tive growth.
dict where and when a flower is to appear.
Our objectives were to determine what
This is particularly true in those locations
treatments could cause 90-100% of
for the first time:
where flowering occurs
bourse buds to shift from the vegetative to
predicted (Crabbe, 1984) with
be
they can
the floral state and to define precocious
a satisfying probability for fruit growers’
signs of this change in meristematic ac-
purposes, but any precise physiological or
tivity.
biochemical approach requires more than
probability. Consequently, although
mere
the start of floral initiation is rather accu-
rately known in fruit species, sound Materials and Methods
information about floral induction and
evocation is still lacking.
Six yr old apple trees, cv. Golden delicious,
As a preliminary to this necessary pre- were used throughout. Bourses formed in the
current year, on which young fruits were deve-
diction problem, we began experimenting
loping, were labeled in early spring. Later, some
on apple ’bourse’ shoots. The bourse is
bourses with short arrested shoots (i.e., spurs)
the swollen basal part of an inflorescence
and others with long shoots (ca 20-30 cm)
axis at the onset of fruit development; it were further selected and treated separately.
bears leaves whose axillary buds differen- Treatments, generally known to increase
tiate and may grow out as shoots. The flower formation, though imperfectly interpreted
on physiological grounds, were: branch ringing,
bourse shoot can flower again in the
young fruit removal from the treated bourse
following years and so, by repeated and, on the long bourse shoots, summer prun-
flowering, a cluster of stacked similar ing. These treatments were applied alone or in
structures appears on old trees. Once combination, at different dates from mid-May to
formed, a bourse is thus a known site for September.
Buds were sampled fortnightly on treated and (Fig. 3, top) and, together with ringing and
control branches for dissection and primordia fruit removal, enabled full completion of
counting, until the plastochron decrease floral initiation (Fig. 3, bottom). However,
appeared as the earliest sign of floral initiation
when applied too early, pruning made the
(Fulford, 1966a, b, c; Abbott, 1977). Terminal
uppermost buds break out immediately as
buds of spurs and terminal and lateral buds on
long shoots, intact or pruned, were considered leafy shoots. Depending upon the inser-
separately. tion level of the bud, the best time for
pruning shifted from late June for the
lower buds to late July for the upper ones.
Results
Discussion and Conclusion
The terminal buds of spurs began to form
in early May. So all treatments from mid-
May to early July appeared to increase A complete shift of the bourse buds to
node formation within the bud. Neverthe- flower formation was thus obtained by fruit
less, branch ringing and fruit suppression suppression on the bourse plus branch
needed to be combined to obtain over ringing, when applied at a time compatible
90% flowering (Fig. 1, bottom). The most with the need to shorten the plastochron.
precocious treatments seemed the most For lateral buds on long shoots, pruning
active in terms of percentage of flowering, was a further requisite.
although those applied from mid-June to The enhanced accumulation of nodes
early July yielded the fastest response in within the bud was a good early marker of
node number increase (Fig. 1, top). On
this shift. But rneristematic activation was
the average, a bud which reached over 18
itself a consequence of even more preco-
nodes at the end of July presumably
cious changes. Our results, repeated
became floral.
during 3 successive years, suggest that
In the selected long shoots, growth we have the experimental system neces-
arrest occurred after mid-June. At that sary to proceed further in this research.
time, bud formation had already started in
lateral buds. However, the terminal bud
formed much faster so that, by late
References
August, it already had about 15 nodes,
while the laterals lingered around 10-13
(Fig. 2, top). Once again, branch ringing Abbott D.L. (1977) Fruit bud formation in Cox’s
and fruit removal combined, applied in Orange Pippin. Annu. Rep. Long Ashton Res.
Sta. 1976 167-l,76
July, brought the terminal to 90% flow-
ering, but failed to do so for the laterals Crabbe J. (1983) Vegetative vigor control over
location and fate of flower buds in fruit trees.
(Fig. 2, bottom). Acta Hortic. 149, 55-63
But pruning those long shoots, right
Fulford R.M. (19 b, c) The morphogenesis
66a,
1
above the median lateral buds, remarka- of apple buds. I, II, III. Ann. Bot. 29, 167-180;
bly increased node formation within these 30, 25-38; 209-2199
Thêm vào BST
Báo xấu
Download
Vui lòng tải xuống để xem tài liệu đầy đủ
