Tree Genetics and Molecular Breeding 2015, Vol.5, No.1, 1
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Table 2 Timber volume associated attributes of polyclonal and multiclonal Population in 20
th
year of growth age
Planting stock
Branching height (m)
Number of primary branches
Bole volume (m³ /tree)
Polyclonal
4.59
2.05
0.27
Multiclonal
3.00
2.40
0.08
SE
0.52
0.14
0.06
CV
25.48
8.01
76.53
Yield evaluation of the polyclonal seedling population
over the years revealed that certain genotypes are
exceptionally good performers. The performance of
these elite seedlings was closely assessed for growth,
yield and other secondary characters. The criteria for
selection were consistent yield over months and years,
good girth increment and other secondary characters
as branching and canopy structure. Based on which
ten numbers of elite mother trees (ortets) were
selected for further multiplication.
The mean dry rubber yield of the ten elite mother
seedling trees over the five years was comparatively
high and ranged from 36.32 g t̵
ˡ t̵
ˡ to 75.40 g t̵
ˡ t̵
ˡ.
The elite seedling trees showed higher yields as
against the base polyclonal seedling population as
well as the multiclonal population (Table 1; Table 3).
The mean annual dry rubber yield of the ten elite
seedling mother trees was two to three folds higher
than that of the multiclonal population. The mean
annual yield was recorded highest in the elite
seedling OR2 (75.40 g t̵
ˡ t̵
ˡ) followed by OR3 (69.04
g t̵
ˡ t̵
ˡ) and OR7 (64.18 g t̵
ˡ t̵
ˡ) (Table 3). Gupta et al.
(2001) and Krishan (2013) have also reported
reasonable yield of polyclonal population in the dry
sub humid region. The rubber yield increased
gradually with the onset of monsoon particularly in
the month of August, peaked in subsequent period,
sustained up in November and started slight decline
thereafter. Yields were comparatively low during the
period from April to July, high during October and
November and moderate during the remaining
months (Figure 2). The general trend observed is in
agreement with the earlier reports in the dry sub
humid region (Chandrasekhar et al., 1990; Birari et
al., 1998) and north eastern region (Sasikumar et al.,
2001; Mondal et al., 2006).
Table 3 Performance of polyclonal elite mother trees
Elite Tree Girth at opening
of tapping (cm)
Annual girth increment over 8
years (cm)
Annual mean yield
over 5 years (g t
-1
t
-1
)
Bole volume at 20
th
year (m³/tree)
Bark thickness at
20
th
year (mm)
Prior tapping
After tapping
OR1
84.4
10.16
2.39
40.02 (9)
0.20
8.00
OR2
82.2
9.91
2.66
75.40 (1)
0.24
11.00
OR3
77.7
9.31
2.41
69.04 (2)
0.16
12.00
OR4
81.3
9.79
2.85
59.98 (4)
0.27
7.20
OR5
75.2
9.09
4.13
58.32 (5)
0.44
9.00
OR6
77.1
9.26
4.43
53.76 (6)
0.43
8.10
OR7
77.1
9.20
4.68
64.18 (3)
0.17
8.00
OR8
74.5
8.88
2.04
36.32 (10)
0.16
6.20
OR9
81.5
9.86
1.31
49.32 (7)
0.13
9.10
OR10
79.9
9.63
4.01
45.64 (8)
0.50
13.00
Mean
79.09
9.50
3.09
54.89
0.28
9.16
SE
1.02
0.12
0.36
3.38
0.04
0.68
CV
4.11
4.22
36.91
22.15
50.45
23.64
Mean*
50.41
5.95
2.58
34.02
0.27
10.16
Note: * Base polyclonal population; figures in parenthesis depicts ranking of mother trees
