ANATOMICAL STUDIES ON REGENERATED BARK OF HAIL DAMAGED HEVEA BRASILIENSIS TREES-A CASE STUDY K.K. Vinod* and Vinoth Thomas Rubber Research Institute of India, Kottayam 686 009, Kerala, e-mail:
[email protected] *Hevea Breeding Sub-station, Kadaba 574 221, Karnataka E-mail:
[email protected] ailstorms are a regular
ing 1980 at t h e Research
normal and regenerated bark
phenomenon in the
Farm of the Rubber Research
for all characters (table 1 ). Ex
NorthEast India dur
Institute
cept for density of tannin
ing the pre-monsooon
Taranagar,
of
India
at
Agartala
filled cells, all other charac
period. Though their inten
(91°15'E; 23(l53'N; 30m MSL)
ters showed significant re
sity used to be mild, occur
constituting five clones viz.,
duction in regenerated bark
rence of strong hailstorms
RRII 105, RRII 118, RRII 203,
than normal bark, whereas
causing severe damage is not
RRIM 600 and RRIM 605
tannin accumulation was
unusual in this region. Hevea
were selected for the study.
high in regenerated bark. The
brasiliensis Muell Arg., the
The trial was planted i n
clone
Para rubber tree is reported
randomised blocks with three
tion showed non-significant
x
side affected interac
to suffer extensively under
replications. Five trees were
variation for all clones indi
hailstorm damage. An inci
selected randomly from each
cating that they suffered equally of hail damage.
dence of such a devastating
clone and bark samples were
hailstorm was reported from
collected at three different
The mean data on num
r u bber
b e r of latex vessel rows
at
loci both at damaged and
Agartala, Tripura in 1986
normal sides. The bark
(NLVR), density and diam
(RRII, 1987). A detailed de
samples were fixed i n Form
eter of latex vessels and den
scription of this damage and
aldehyde-Acetic acid-Alco
sity of tannin filled cells are
its consequences were re
hol (FAA) mixture. Sledge
given in table 2. Data on
ported by Meenattoor et.al.,
microtome sections of 25 J.im
NL VR and density of latex
(1995), which
a
thick were taken and stained
vessels showed no signifi
yield reduction on regener
}Vith combination of Safra
cant variation among clones
ated bark, the production be
nin-0 and Fast green FCF for
in virgin bark. However, on
plantations
�scribed
ing about 36% less than that
general histology, tannic
regeneration these two traits
of the virgin bark. The
acid-ferric
for
showed significant variation
present study was aimed at
tannins Oohansen, 1940) and
among clones. In renewed
investigating the anatomical
Sudan III for latex vessels
bark, RRIM 605 had the high
differences in hail damaged
(Premakumari et. al., 1996).
est average number of 7.93
and virgin bark as a possi
Sections were examined
rows of latex vessels while
bility of explaining the yield
through a projection light mi
RRIM 600 recorded the low
chloride
reduction experienced and
croscope for anatomical in
est of 6.07 rows. On the con
other anatomical conse
vestigations. Data were
trary, RRIM 600 had more
quences of wound healing
analysed statistically.
vessels per unit area (56.16/
process.
Analysis of variance re
mm) while RRIM 605 re
A severely damaged clone
vealed that highly significant
corded the least (44.44/mm).
evaluation trial, planted dur-
variation existed between
This indicated that response
9
to regeneration varied among
tent areas of intact virgin
RRIM 605 showed relatively
clones conforming to the ear
bark. This resulted in devel
higher density for tannin
lier study by Meenattoor etal.,
opment of islands of regen
cells both in virgin and re
(1995). Though diameter of
erated and virgin bark on the
newed bark when compared
latex vessels was found re
entire affected side. A tap
to other clones indicating
duced significantly in regen
ping cut made in this area
their inherent ability of tan
erated bark than virgin bark,
would cut through virgin
nin production.
no acceptable clonal varia
and
barks
Major difference between
tion could be observed in ei
throughout its length. This
hailstorm damage and tap
r e g en e r a t e d
ther case. Of the three traits,
unusual situation could ex
ping is the extent of wound
N LVR, density and diameter
plain the yield depression
ing. In tapping, a controlled
of latex vessels, NLVR was
observed on affected side.
wound is made leaving a
reported to be the most im
Tannins are known to be
thin inner bark external to
portant parameter in yield
the most important defensive
cambium (shallow wound
determination
(Gomez,
secondary metabolite pro
ing). This residual inner bark
1982). Lowest yield recorded
duced as a result of wound
is instrumental in healing
for RRIM 600 in the same ex
ing (Swain, 1965). In the
and completes regeneration
perimental
by
present study, unlike other
process (Thomas et.al., 1995
Meenattoor et al., (1995) could
traits, density of tannin-filled
b).
be due to low NLVR values
cells had wide variation
gap between two successive
recorded by this clone in both
among clones in virgin and
tapping facilities healing
virgin and regenerated bark
renewed bark. Regenerated
process. During hail damage
area
Moreover, a distinct time
even though it had higher
bark had more density of tan
a large area was affected with
density of l a t e x vessels.
nin-rich cells than virgin
wounds ranging from shal
Webster and Paardekooper
bark for all the clones. The
low to deep (either involving
(1989) had reported that den
abundance observed in re
cambium or not), in a single
sity and diameter of latex ves
newed bark indicated that
instance (Thomas et al., 1995
sels had little contribution to
wound - healing
process
a). Deeper wounds often re
wards yield. In the present
could have stimulated tannin
main partially close exposing
case, it was observed thatthe
production. Similar response
wood, due to lack of complete
hailstorm chipped off almost
on wound healing during
cambial activity. It was also
75% of bark on one side of the
normal tapping was reported
established that speed of re
tree upto a height of 4-5 m
by Thomas et al., (1995
covery is often regulated by
from base leaving intermit-
Two clones, RRII 105 and
b).
the extent of injury (Kramer and Kozlowski, 1979). This
Table 1. Variation component mean squares for the characters by pooled analysis of variance
was because wounding
No. of latex vessel rows (per mm)
Density of latex vessels ( Jlm)
Diameter of latex vessels (per mm)
sues and thereby interrupt
Clone (C)
1.204*
221.335*
5.357
1287.716*
sary for production of new
Side (S)
5.368*
1047.134*
218.700*
19423.95*
vascular tissues (Aloni,
C xS
o.417
73.414
3.716
222.462
1995). Therefore wider the
Residual
0.495
36.535
4.953
129.348
Source of Variation
Residual df
=
18
* Significant at
Density of tannin cells
would damage vascular tis ing translocation of hor mones, which may be neces
5% level
damaged area, slower would be the recovery. This was evi dent from the fact that, even
10
Table 2. Mean values of anatomical traits in virgin and regenerated bark of five clones
Clone
No. of latex vessel rows
Density of latex vessels (per mm)
Diameter of latex vessels (flm)
Density of tannin cells {per mm)
the performance of the re covered trees. Indian Jour nal of Natural Rubber Re search, 8: 51-53. Premakumari, D., Panikkar, A.O.N ., Marattukalam,
a) Virgin bark RRII 105
7.73
56.73
21.34
23.55 a
RRII 203
8.16
55.33
21.80
1.33 b
RRII 118
7.87
69.60
19.68
12.88 b
RRIM 600
7.60
60.27
21.70
32.89 a
RRIM 605
8.20
57.16
19.86
37.33 a
V�ratio
0.212
1.435
0.543
4.304
ns
ns
ns
10.028
SE(d)
(1996). Yield and ana tomical characters in Hevea: A path coefficient analysis
and
characterisation
of
clones. Indian Journal of Natural Rubber Research, 9:12-16.
b) Regenerated bark RRII 105
7.00 b
35.95 d
15.92
88.89 a
RRII 203
6.93 b
49.73 be
17.46
59.12 b
RRII 118
7.40 ab
53.73 ab
15.46
54.65 b
RRIM 600
6.07 c
56.16 a
13.62
68.21 b
RRIM 605
7.93 a
44.44 c
14.92
91.56 a
Variara!ratio
12.045**
19.373**
1.687
7.212**
0.280
2.593
ns
8.921
SE(d)
J.G. and Sethuraj, M.R.
RRII (1987). Annual Report for 1986-87. Rubber Re search Institute of India, Kottayam. pp. 100-102. Swain, T. (1965). The tannins, In: Plant Biochemistry, (eds. J. Bonner and J . Varner). Academic Press, New York, pp. 552-580.
** significant at 5% level ns=non-significant Means followed by same letters are not significantly different at 5%
Thomas, V., V inod, K.K. and Pothen,
level by LSD test.
J.
(1995
a),
Wounding in Hevea trees, Rubber Board Bulletin, 27: though the present study was
of Hevea and its influence
19-23.
taken up after eight years of
on latex production.
Thomas, V., Premakumari,
hailstorm damage, affected
MRRDB Monograph No.
D., Regh u, C.P., Panikkar,
trees were found not to regain
7 , Kualalumpur, 54 p.
complete anatomical features
Johansen, D.A. (1940). Plant
Saraswathyamma, C.K.,
as far as the lacticiferous sys
Microtechnique. McGraw
(1995 b). Anatomkal and
tem is concerned.
References Aloni, R. (1995). The induc
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Press, New York, 811 p. Meenattoor, J.R., Vinod K.K.,
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