With a mission to achieve improvements
in productivity and profitability of plantations, the
company focused on genetic improvement of planting stock
and improvement of the package of practices. Major gains
in productivity of eucalyptus plantations have been
achieved in the short span of 12 years through applications
of cloning techniques for gainful exploitation of existing
useful variation.
At the beginning of eth programme, the main handicap
faced was the non-availability of a wide genetic base
for the improvement of eucalyptus. Therefore, a “Breed
the best with the available best” strategy
was followed. The genetic base deployed improvement
is given in fig 1.
Candidate Plus Tree (CPT) Selection:
The selection of the most desirable tree with characteristics
such as straightness of stem, annual growth rate,
disease resistance, crown structure, wood density,
fiber morphology, cellulose/lignin balance, bark to
solid wood, under bark relationships etc. were considered.
Trees were selected from Government (Andhra Pradesh
Forest Development Corporation – APFDC) and
Farmers plantations. Starting with the cloning of
64 CPTs during 1989, more than 650 CPTs and 247 full
sib CPTs have been selected and cloned by now. Out
of 86 promising clones qualified so far, 54 (63%)
have come from the provenance seeds source obtained
from CSRIO (Australia) and 32 (37%) from local Mysore
gum. The provenance’s that gave maximum clones
are 8 KM NW Black Mountain and 1 KM N of Laura (Fig
1).
Productivity of Clones: The survival
percentage of the majority of clonal plantations is
reported to be more than 95 per cent, which is unheard
of in Indian forestry (Kulkarni and Lal 1995). The
productivity of “Bhadrachalam” clones
range from 24 to 58 m3/ha/yr compared to 6 to 10 m3/ha/yr
from seedling origin plantations (fig 2 to 4 ). Apart
from increases in productivity by 4 to 6 times the
rotation period is reduced by half (fig 5). Therefore,
the farmers are now harvesting plantations at 4 to
5 years instead of 7 to 8 years.
Clonal Multiplication Areas (Gene Bank):
Since 1989, the CPT material has been first planted
in the Gene banks. For the large-scale commercial
production of plants, a Gene bank of promising clones
was established in 26 ha with nearly 0.2 million ramets.
The clones were planted in blocks at closer spacing
of 1 x 1 m. Gene banks are coppiced at 2 years age
for obtaining the propagule for multiplication.
Improvement for Pulp and Paper Quality:
As soon as the CPT was selected it was first tested
for proximate chemical analysis and strength properties.
A few clones have given 49 per cent screened yield
compared to 45 per cent from seed route plantations.
Over the last two years much emphasis has been laid
on improving the fiber quality by hybridizing clones
with the best fiber properties. The best fiber for
papermaking is derived from species like E.globulus,
E.deglupta, E.urophylla etc. apart from their high
growth potential. Therefore, a few high yielding “Bhadrachalam”
clones are now being hybridized with the above species
to achieve twin objectives of improving fiber properties
and inducing drought resistance so that new hybrids
developed are adaptable to sub-tropical agro-climatic
conditions. |
