Open Journal of Forestry
2014. Vol.4, No.1, 38-41
Published Online January 2014 in SciRes (http://www.scirp.org/journal/ojf) http://dx.doi.org/10.4236/ojf.2014.41007
38
Prolonged Seed Dormancy in Phyllanthus emblica L. Can Be
Overturned by Seed Scarification and Gibberellin Pre Treatment
S. M. U. P. Mawalagedera1, G. A. D. Pe rera2, S. D. S. S. Sooriyapathirana1
1Department of Molecular Biology and Biotechnology, Faculty of Science,
University of Peradeniya, Peradeniya, Sri Lanka
2Department of Botany, Faculty of Science, University of Peradeniya, Peradeniya, Sri Lanka
Received September 26th, 2013; revised November 3 rd, 2013; accepted November 26th, 2013
Copyright © 2014 S. M. U. P. Mawalagedera et al. This is an open access article distributed under the C reative
Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium,
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et al. All Copyright © 2014 are guarded by law and by SCIRP as a guardian.
Phyllanthus emblica L. is an important constituent of Ayurvedic medicine and a fresh fruit species in the
market in Sri Lanka. Therefore, it has a high potential to be established as a commercial fruit crop. The
seeds of P. emblica are semi orthodox and exhibit a long dormancy period hindering the natural sexual
propagation. Therefore, it still remains as an underutilized fruit crop in Sri Lanka due to its lack of quality
planting material and poor propagation techniques. Long term dormancy also causes a big challenge in
germinating seeds to create populations in breeding programs. In order to promote P. emblica from its
underutilized status, what seems most feasible is to develop a method to break up the seed dormancy arti-
ficially. In order to do so, the methods of breaking the dormancy of P. emblica seeds have to be studied.
Therefore, the aim of this study was to identify a method to break up the seed dormancy of P. emblica.
The seeds were extracted from 21 trees belonging to three different districts in Sri Lanka. The selected
viable seeds were subjected to four different pre treatments: none treated seeds (i.e. control), seeds scari-
fied, seeds scarified and treated with 1% gibberellin and seed coat removed and followed by seeds treated
with 1% gibberellin. From the four treatments, seed dormancy was overturned with a germination per-
centage of 43% by the seed pre treatment where the seeds were scarified and treated with 1% gibberellin
and no other pre treatment methods were successful in breaking the dormancy. This suggests that the nat-
ural germination potential of P. emblica seeds is very low and it can be overridden by seed scarification
and gibberellin pre treatment.
Keywords: Gibberellin Pre Treatment; Phyllanthus emblica; Seed Dormancy; Seed Scarification
Introduction
Phylanthus emblica L. is a deciduous and monoecious tree
belonging to family Euphorbiaceae. Fruit is fleshy and drupa-
ceous and the seeds are found within the hardened endocarp of
the fruit known as stone (Dassanayake & Fosberg, 1988). P.
emblica is famous for its medicinal values. In tra ditional medi-
cine, it is known as one of “the best rejuvenating herbs”
(Krishnaveni & Mirunalini, 2011). All the parts of the tree are
medically important (Pushpakumara et al., 2007), but the drupe
is the most important. There is a significant market demand for
fresh drupes because it relieves fatigue, increases the appetite
and also acts as a good purgative (Krishnaveni & Mirunalini,
2011). The pharmacological studies indicated that drupes show
antioxidant and antiproliferative activities attributed to the
phenolic compounds in the drupes (Lou et al., 2011), hig-
hlighting the importance of P. emblica. However, it is still an
underutilized fruit crop in Sri Lanka due to unavail ability of high
quality planting material and poor propagation techniques
(Pushpakumara et al., 2007).
The seeds of P. emblica exhibit a long dormancy period. The
observations indicated that the natural sexual propagation po-
tentia l of P. emblica is very poor and the seed behaviors as semi
orthodox (Pushpakumara et al., 2007). Under natural conditions,
P. emblica seeds are dispersed either through ruminants (Prasad
et al., 2006) or by passive means. But there is a high tendency
towards passive means of dispersal. Therefore, under natural
conditions, this semi orthodox behavior and long-term dormancy
aid the seeds to remain viable until the seeds come into contact
with the proper substratum for germination. But in terms of
agronomy, this is a major drawback in implementing large scale
P. emblica plantations (Pushpakumara et al., 2007). Also in
setting up breeding programs, long-term dormancy causes a big
challenge in germinating seeds to create populations . Thus, there
is a need to develop a method to break up the seed dormancy
artificially. In order to do so, the methods available to break the
dormancy of seeds have to be studied extensively for P. emblica .
In India where P. embl ica is well established as a commercial
fruit crop, this problem is tackled through alternative vegetative
propagation techniques. In addition, they predominantly depend
on tissue culture techniques (Pushpakumara et al., 2007). The
drawbacks in tissue culture techniques were addressed through
developing in vitro shoot proliferation (Goyal & Bhadauria,

S. M. U. P. MAWALAGEDERA ET AL.
39
2007) though it is costly and cannot be implemented in breeding
through sexual propagation.
The aim of this study was to ident ify a method to b reak up the
seed dormancy of P. emblica. The proposed method would help
to sever the seed dormancy and promote P. emblica from its
underutilized status through increasing natural propagation
potential and easing the breeding effort.
Materials and Methods
Collection of Drupes from P. emblica
The mature drupes were harvested from P. emblica trees in
three selected areas of Anuradhapura, Kandy and Kurunegala
districts, Sri Lanka from February to April 2013. From each
district drupes from seven selected trees were used to obtain
seeds adding up to a bulk sample of 21 trees for seed dormancy
analysis.
Extraction of See ds
The mesocarp of the drupes was cut open and completely
removed (de pulped) using a knife and the stones were left to
air dry for 24 hours. The stone (Figure 1) was split opened by
applying a light pressure longitudinally. From each drupe up to
four seeds were extracted. The extracted seeds were air dried
for 24 hours.
Selection of Viable Seeds
The extracted seeds were kept in a jar containing water and
were subjected to float test to determine seed viability. The
seeds that sank to the bottom were selected for pre treatments.
Seed Pre Treatment and Germination
Prior to sowing, all the equipment (i.e. forceps, scalper and 3
ml syringe) used in sowing seeds was disinfected using 1%
Clorox solution (The Clorox Company, Oakland, Canada). The
four seed pre treatments used were none treated seeds (i.e. con-
Figure 1.
Placement of seeds within the P. emblica stone across a longi-
tudinal cross section, A: Seed within the stone, B: stone/har-
dened endocarp, C: mesocarp. The same color is used for the
arrow and for the corresponding letter showing the placement
of seeds within the P. emblica drupe.
trol), seeds scarified, seeds scarified (partially removed) and
treated with 1% gibberellin (Wako Pure Chemical Industries,
Osaka, Japan) and seed coat removed and treated with 1% gib-
berelin. The seeds after pre treatments were germinated by
placing on moistened paper towel. A single seed was sown in a
paper towel and placed inside a zip lock bag with the mouth
open and kept in a well aerated area with direct morning sun-
light. The seeds were watered weekly with 1 ml of tap water
using a disinfected syringe. The seed germination was observed
closely and the number of seeds that have germinated from
each treatment was counted.
Results
The Effect of Pre Treatments on Seed Dormancy
The four seed pre treatments to break the seed dormancy
used were untreated seeds, seeds scarified, seeds scarified (par-
tially removed) and treated with 1% gibberellin and seed coat
removed and treated with 1% gibberellin. Out of the four seed
pre treatments, none of the seeds from none treated (Figure
2(A)); seeds scarified (Figure 2(B)) or seed coat removed and
treated with 1% gibberellin (Figure 2(C)) showed germination
even after three months. However, nine seeds that were sub-
jected to seed scarification and 1% gibberellin pre treatment
germinated exactly after 85 days of pre treatment with a ger-
mination percentage of 43% (Table 1). Complete seedlings
(Figure 2(D)) with approximately 5 cm long radical and the
cotyledon were emerged on the paper towel (inside the zip lock
bag) within a week of liberating from the dormancy.
Discussion
Among the four seed pre treatments, none treated, seed coat
scarified, seed coat removed and treated with 1% gibberellin
did not have any effect on breaking the dormancy of P. emblica
seeds. The highest effect on breaking the seed dormancy was
shown by the seed pre treatment where the seed coat was scari-
fied and treated with 1% gibberellin. This suggests that the
natural germination potential of P. emblica seeds is very low.
Therefore large scale P. emblica plantations are predominantly
dependent on vegetative propagation. It can be vegetatively
propagated through cutting, budding and inarching (Pushpaku-
mara et al., 2007). But vegetative propagation is a difficult and
a slow process (Goyal & Bhadauria, 2007). Therefore many of
the commercial growers of P. emblica are using in vitro rege-
neration methods (i.e. tissue culture). Through recent studies
done in neighboring India, they have been able to develop trip-
loid plantlets from the endosperm of P. emblica using in vitro
propagation (Pushpakumara et al., 2007). Yet shoot prolifera-
tion in these in vitro explants are found to be poor (Goyal &
Bhadauria, 2007). Therefore there is an urgent need to develop
Table 1.
Germination percentages of four pre treatments.
Treatment Germination
percentage (%)
None treated seeds 0
Seed coat s carified 0
Seed coat s carified and treated with 1% gibberellin 43
Seed coat removed and treated with 1% gibbere l l i n
0

S. M. U. P. MAWALAGEDERA ET AL.
40
Figure 2.
Germination among pre sowin g treatments of P. emblic a seeds; (A) Ungerminated seed none treated; (B) Ungerminated seed pre treated wit h
1% gibberellin and removal of seed coat; (C) Ungerminated seed pre treated with seed scarification and (D) Seedling developed from seed pre
treated with 1% gibberellin and seed scarification. Scale bar represent 1 cm. The photos were taken after 92 days of the pre treatment and
placement on the moist paper towels for germination.
a successful micro propagation protocol for P. emblica in order
to expand its commercial market.
According to the observations made P. emblica seeds seem
to have seed coat imposed dormancy as in peach (Mehanna &
Martin, 1985). Research conducted with Arabidopsis gibberel-
lin deficient mutant strains indicated that, seed coat imposed
dormancy can be overridden by application of gibberellin at the
stage of germination (Foley, 2001). It has been found that
gibbrrelin can induce the expressions and repression RGL2
(gibbrrelin-response height-regulating factors) which acts as an
integrator of environmental and endogenous cues for germina-
tion (Peng & Harberd, 2002). Therefore by manipulating the
concentration of gibberellin during seed pre treatment it would
be possible to change the germination percentage and reduce
the time taken for germination. In species such as Penstemon
digitalis the germination percentage and rate increases up to a
threshold concentration of gibberellins (Mello et al., 2009).
However it is inconclusive to comment that gibberellin concen-
tration has a directly proportionate variation with germination
percentage in P. emblica.
The seeds of P. emblica are enclosed within a hardened en-
docarp of approximately 1 cm in diameter (Dassanayake and
Fosberg, 1986). To break the seed coat imposed physical dor-
mancy scarification of seed coat was used. It has resulted in
increasing the germination potential of many species as African
Locust Bean (Aliero, 2004) and Pedicularis (Li et al., 2007). In
Indian dry forests P. emblica seeds are dispersed by ruminants
(Prasad et al., 2004). But seeds regurgitated by ruminants have
a lower germination potential (22%) than seeds which are un-
consumed (72%; Prasad et al., 2004). Other than ruminants no
other species have shown frugivore in relation to P. emblica
(Prasad et al., 2004). This could be due to the high astringency
of the drupe. Therefore it is possible that the seeds of P. embli-
ca undergo passive dispersal. Passive dispersal requires long
term viabi lity of the seed unti l the seed come in to c ontact with
a suitable substratum. It is possible that this seed coat imposed
dormancy of P. emblica is a safety measure to maintain the
viability of seeds until landing on to an appropriate microenvi-
ronment. Thus the seeds of P. emblica are classified as semi
orthodox (Pushpakumara et al., 2007).
In summary these observations and results shows that P. em-
blica has a high seed coat imposed dormancy which can be
overridden by gibberellin pre treatment. Yet further studies are
needed to assess the effect of plant growth regulators control-
ling the P. emblica seed dormancy in order to provide quality
planting material for growers which will help to promote P.
emblica from its underutilized fruit crop status.
Conclusion
The seed dormancy of P. emblica can be overridden by the
pre treatment where the seed coat was scarified and treated with
1% gibberellin. This method can be used to germinate seeds of
P. emblica in breeding programs and in any other studies which
require seedlings.
Acknowledgements
This project was funded by University of Peradeniya, Sri
Lanka Research Grant (RG/2013/15/S).
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