Agriculture Reference
In-Depth Information
Table 9.1.
Effect of temperature and cultivar on percentage of litchi terminal
branches
fl
owering. Trees at 25/20°C and 30/25°C did not
fl
ower (Menzel and
Simpson, 1988). Panicles can be of two types; one has only
fl
owers, while the other
has a mixture of leaves and
fl
owers, and is referred to as a leafy panicle.
Branches
fl
owering %
Cultivar
Vegetative shoot
Leafy panicles
Lea
fl
ess panicles
Flowering panicles
15/10°C
20/15°C
15/10°C
20/15°C
15/10°C
20/15°C
15/10°C
20/15°C
Da zao
0
50
93
50
7
0
100
50
Bengal
0
49
71
32
29
9
100
41
Shui dong
0
58
39
3
61
28
100
31
Gui wei Pink
0
20
55
69
46
8
100
77
Gui wei Red
0
80
7
3
93
5
100
8
Salathiel
0
17
0
20
100
58
100
78
Huai zhi
0
4
0
14
100
81
100
95
yields, as poor fruit set occurs at 33°C. In hot equatorial areas, litchi grows
vegetatively and seldom fl owers.
Longan is less demanding than litchi for fl owering, requiring 15-22°C
for 2-3 months for fl ower induction (Fig. 9.1). The exact chilling and cultivar
dif erences in this requirement are not known. In hot equatorial areas, longan
grows vegetatively and seldom fl owers. Flowers can be induced by a chemical
treatment discussed below.
Light intensity and photoperiod
Litchi is a day-neutral plant, and fl oral initiation is associated with starch
content of leaves and stems. Shading, such as when litchi trees begin to crowd
each other in an orchard, leads to a decline in production, due to smaller
panicles and a decrease in the number of panicles on a tree (Lin
et al.
, 1991).
Shading to 50% of full sunlight causes a 40% reduction in the panicles formed
and a 65% reduction in panicle length. There is little information on the
response of longan to varying light levels; it is thought to be day neutral.
GENERAL CHARACTERISTICS
Tree
The litchi is a spreading evergreen tree, growing to 10-12 m under favourable
conditions. It is generally considered to be a slow grower with a long life. A
Chinese writer, Wen Hsun Chen, said that at the time of his writing (before
1924), the cultivar 'Chenzi' (Chen Family Purple, 'Brewster') was already
300 years old and still thriving (Grof , 1921). Depending upon cultivar, trees
may be broad with low-hanging branches or have upright branches and a
compact, rounded head. Branches are brittle and even large limbs are easily
broken by winds.
