Tree Genetics and Molecular Breeding 2015, Vol.5, No.1, 1
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plantations have potential to screen and evolve
higher yielder clones besides several advantages
such as ease in establishment, vigorous growth and
good survival in adverse conditions (Simmonds,
1989).
In polyclonal seedling experiment, stumps of 776
polyclonal seedling of
Hevea brasiliensis
were field
planted in 1989. The experiment was laid out in
completely randomized, single tree- single plot
design planted at a spacing of 4.6 m×4.6 m. The
seedling trees were raised from seeds procured from
polyclonal seed gardens in Kanyakumari district in
Tamil Nadu state in the traditional belt of India.
Experiment comprising of the budded multiclonal
population was planted in the nearby field. In the
multiclonal experiment three clones RRII 105,
RRIM 600 and GT 1 (Table 4), were laid out in
randomized block design with 36 plants per plot in
eight replications. Brown budded stumps were used
as planting material and field planted at a spacing of
4.6 m×4.6 m. The multiclonal and polyclonal trees
were raised following similar cultural practices
recommended for the growing of rubber (RRII,
1990). In the first two years of field planting of
polyclonal seedlings and multiclonal population, the
plants were provided partial life saving irrigation of
20 L per week during summer months.
Table 4 Parentage and country of origin of multiclonal
population
Clone
Parentage
Country of origin
RRII 105
Tjir1×Gl 1
India
RRIM 60
Tjir×PB 86
Malaysia
GT 1
Primary clone
Indonesia
The growth was recorded as the girth of the trunk.
The trunk girth was recorded at regular intervals as
per standard practice at above ground level of 110
cm for polyclonal seedling trees and at 150 cm for
the multiclonal population. The standard of
recording is different for seedling and budded
multiclonal owing in the difference in the anatomy
of bark and shape of the trunk.
The trees were opened for tapping at the eighth year
after planting under 1/2S d/2 6d/7 tapping system
(Half spiral, alternate daily, six days in tapping
followed by one day rest). Dry rubber yield was
recorded twice a month. Yield recording is done by
cup coagulation. Two coagulations representing the
first half and the second half of a month are carried
out. Coagulation is effected by mixing a few drops
of dilute (0.5%) formic acid with the latex in the
cups after the flow has ceased. The resultant cup
lumps are hooked on to labeled hooks on the day
after coagulation. The hooked cup lumps are dried in
the smoke house for a month and weight of dried
cup lumps are recorded. The yield is estimated from
the weight of cup lumps thus recorded. Data on the
yield over five years of tapping from the fourth year
to ninth year were utilized for evaluating the
performance of polyclonal and multiclonal
population. Ten polyclonal elite mother trees were
identified as potential ortets based on yield and
secondary attributes.
Clear bole volume of polyclonal and multiclonal
population was estimated using first branch height
and girth in the twentieth year after planting
following the quarter girth method (Chathurvedi &
Khanna, 1982). The bark thickness of polyclonal and
multiclonal population was measured in the
twentieth year after field planting. Recording on the
tapping panel dryness and wind damage was also
undertaken. Plants with 80%~100% panel dryness
incidence were considered as tapping panel dryness
affected trees. Wind damage category included
uprooted or trunk snapped trees. The data were
statistically analyzed followed Sukhatme and Amble
(1989).
Acknowledgement
The author is thankful to Director, Rubber Research Institute
of India for his constant encouragement. The help of all
associated scientists and field staff is also acknowledged.
References
Birari S.P., Shinde A.K., Thavare B.L., and Bhave S.G., 1998,
Performance of budgrafts and seedlings of
Hevea brasiliensis
in
laterite zone of Konkan (Maharashtra), Rubber Board Bulletin, 27(3):
31-34
Chandrashekar T.R., Jana M.K., JosephT., Vijayakumar K.R., and
Sethuraj M.R., 1990, Seasonal changes in physiological
characteristics and yield in newly opened trees of
Hevea brasiliensis
in North Konkan, Indian Journal of Natural Rubber Research, 3(2):
88-97
Chandrasekhar T.R., Gawai P.P., and Saraswathyamma C.K., 2002, Yield
performance of trees grown from polycross seeds of rubber (
Hevea
brasiliensis
) in a dry sub humid climate in India, Indian Journal of
Natural Rubber Research
,
15(1): 19-27
Chathurvedi a.n., and khanna l.s., 1982, forest mensuration, international
book disributors, dehradun, india
Fernando D.M., 1974, Trends in the improvement of rubber planting
material with particular reference to sri lanka, Indian Journal of
Genetics and Plant Breeding, 34(a):127-131
