Volume 38 Number 1 Article 1 Pages: 2-5
Year 1984 Month 1
Title: Spur Leaf Characteristics of Nine Apple Cultivars
Authors: C.C. Rom and D.C. Ferree
Spur leaves are important in many
aspects of fruit development.
are the first leaves to emerge from
dormant buds of bearing apple trees,
and comprise the majority of the tree
canopy until shortly after bloom.
(5) has indicated that the new
leaves provide the "greater part by
far" of photosynthates for the growth
of fruit compared to carbohydrates
mobilized from reserves.
of the spur leaves prior to or during
bloom reduces fruit set (1). From a
3-year survey of more than 50 blocks
of Delicious trees in major apple pro
ducing regions, Dennis (2) found that
total solar radiation during the 3 week
period prior to and during bloom cor
related significantly with fruit set.
Spur leaves comprise nearly the entire
tree canopy during this critical period
for fruit set and cell division and exert
an important localized influence on
fruit size, shape and calcium level that
are important for quality and storage
(3). A minimum spur leaf area is nec
essary for flower bud formation (6).
Thus, many studies have indicated the
vital role of spur leaves for fruit de
velopment, but the influence of vari
ous cultivars on spur leaves and other
spur characteristics has not been well
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