RESEARCH ARTICLE
Effect of seed abortion and seed storage on
germination and seedling growth in
Aquilaria malaccensis Lamk. (Thymelaeaceae)
Uma Shankar*
Department of Botany, North-Eastern Hill University, Shillong 793 022, India
The fruit of Aquilaria malaccensis is a bilocular dehiscent capsule, with each locule harbouring a single
seed. If this species aborts a developing seed within a
fruit, does the remaining seed benefit in terms of
enhanced seed weight, and do heavier seeds confer
germination and growth advantages over lighter
seeds? As seeds mature in the middle of the rainy season when moisture is abundant in the soil, does desiccation in the storage of seeds reduce germination
success? To test these predictions, 821 fruits were
examined, including two-thirds fruits that were oneseeded and one-third fruits two-seeded. Fresh seeds
varied nearly fivefold in weight, from 28.8 to 134.8 mg.
However, the mean seed weight did not vary significantly between the seeds from one- and two-seeded
fruits. On storage at room temperature (28 ± 2°C), the
seeds lost 40 ± 1.2% moisture by the 5th day and
55 ± 1.5% by the 14th day. Yet, the difference in mean
seed weight was not significant between the seeds from
one- and two-seeded fruits. Germination percentage of
fresh seeds increased with increase in seed weight:
seeds < 40 mg failed to germinate, those between 40
and 80 mg resulted in 10.5% germination and those
> 80 mg germinated vigorously (54.8%). This trend
was steady when seeds stored for 5 and 14 days were
sown. Germination percentage of all seeds declined
drastically with storage time: from 31 for seeds without storage to 25 for 5 days of storage and only 1% for
14 days of storage. Germination was epigeous and it
was completed within 40 days from sowing. Time to
germination was lesser for heavier than lighter seeds.
Survival of seedlings and their growth from heavier
seeds was significantly greater than those from lighter
seeds. The study shows that the abortion of one of the
two seeds does not enhance the weight of the
remaining seed. Yet greater seed weight (> 80 mg) is
advantageous for better germination and seedling
growth in A. malaccensis.
Keywords: Aquilaria malaccensis, germination, seed
abortion and storage, seedling growth.
extraction of an oleoresin from the diseased portions of
the heartwood, a source of highly prized ‘agar oil’ used in
medicine, perfumery, incense and joss-stick16,17. Of late,
conservation of A. malaccensis has assumed importance,
particularly after its inclusion in Appendix II of the Convention on International Trade in Endangered Species of
Wild Fauna and Flora (CITES) in 1995. Thus, the knowledge of its regeneration ecology is extensively desired
for developing protocols for raising large-scale plantations18. In nature, A. malaccensis regenerates by seeds
that are available in the rainy season. Of late, the genus
Aquilaria has drawn attention of researchers worldwide
resulting in studies on desiccation sensitivity19, storage
behaviour20,21, seedling growth and survival in the
forest22–24, and in vitro propagation25.
This study was undertaken to address the following
questions. First, since A. malaccensis produces both oneand two-seeded fruits, are seeds from one-seeded fruits
heavier than those from two-seeded fruits? Second,
since seeds do not store food reserves besides cotyledons,
do heavier seeds germinate earlier and produce advantageous seedlings than lighter seeds? And third, since
seeds mature during the middle of the rainy season when
moisture is abundant in the soil, does desiccation in the
storage of seeds influence germination success?
TROPICAL trees most often pack lesser number of seeds
within a fruit than the number of ovules within an ovary.
Several factors are responsible for seed abortion, such as
available resource1, pollen limitation2,3, seed predation
and pathogen attack1,4,5, lethal alleles6,7 and self-organization8. Whether seed abortion has a significant effect on
the weight of the remaining seeds is not well known.
Nonetheless, seed size has been shown to influence emergence rate and competitive ability of seedlings9–11. Seed
weight variation within rainforest species12 is known to
have no general effect on the risk of seed removal and
speed of seedling emergence13.
In species with only two ovules (such as Aquilaria
malaccensis Lamk.), fruits can be either one- or twoseeded. A. malaccensis is an extremely important tropical
tree in South East Asia14,15. The species is threatened in
the wild15, but survives mainly in plantations and homesteads in India. The main cause of species depletion is the
*e-mail: [email protected]
596
CURRENT SCIENCE, VOL. 102, NO. 4, 25 FEBRUARY 2012
RESEARCH ARTICLE
Figure 1. Stages of seed germination and seedling development in Aquilaria malaccensis. a, Young plantation; b, Twig
bearing flowers in leaf axil; c, Fruit opened into two halves producing two seeds with a tail-like appendage; d, Epigeous
germination of seed with hypocotyl and cotyledons emerging from the soil; e, Young seedling in which cotyledons remain
covered with testa causing its death; f, g, Normal seedling with emergence of first pair of leaves from the cotyledons and
h, Six-day-old seedling, excavated and removed from soil showing radicle pale-pink in colour and as lengthy as the
plumule.
Materials and methods
The species
A. malaccensis Lamk. (synonym A. agallocha Roxb.) is
commonly known as ‘agar’ in India and as ‘gaharu’ in
Indonesia and Malaysia. A. malaccensis occurs predominantly in the Indo-Burma hotspot of biodiversity26. In
India, it grows in the foothills of Assam and adjoining
states. The species prefers a mean annual rainfall of 1500
to 6500 mm, mean maximum temperature from 22°C to
CURRENT SCIENCE, VOL. 102, NO. 4, 25 FEBRUARY 2012
28°C and mean minimum temperature from 14°C to 21°C
(ref. 27).
A. malaccensis is a medium-sized deciduous tree
attaining 18–30 m height and 1.5–2.5 m girth (Figure
1 a). Flowering occurs from March to May, and fruits and
seeds develop in two months. Bisexual flowers are green
or dull yellow (Figure 1 b). Ovary is superior and the two
carpels join to form two locules. Flowers exhibit entomophilies28. The fresh fruit is a parrot-green capsule
(Figure 1 c). Each capsule has two locules producing up
to one seed in each locule. The capsule dehisces mechani597
RESEARCH ARTICLE
cally and seeds remain hanging in their respective locules
by a persistent funiculus (Figure 1 c). Passive dispersal
results in most seedlings landing within 5 m radius of the
maternal trees28. The seeds are non-endospermic, 6–8 mm
in length and 3–5 mm in width.
Data collection
Fruits of A. malaccensis were collected from Hojai,
Assam in August 2000, and transported to the laboratory
in polythene bags. The fresh seeds were extracted from
the fruits, individually labelled, weighed on an electronic
balance to 0.1 mg accuracy and transferred to laboratory
trays at room temperature (28 ± 2°C). A total of 1000
seeds were sown in three phases: 200 seeds each from
one- and two-seeded fruits immediately after weighing
(no storage) and after 5 days of storage, and 125 seeds
from one-seeded fruits and 75 seeds from two-seeded
fruits after 14 days of storage. Seeds were weighed again
after 5 and 14 days of storage prior to sowing. All seeds
were sown in root trainers, each with 25 holes. Root
trainers were filled with soil collected from the site of
seed collection (lateritic sandy loam) and kept under the
tree canopy to mimic natural environment. Each root
trainer containing 25 seeds represented one replicate and
the root trainers were placed in a randomized block
design. Day temperature ranged between 25°C and 30°C,
and relative humidity between 60% and 80% during the
germination period. Root trainers were watered regularly
to avoid desiccation of surface soil. Germination tests
were conducted according to the international rules for
seed testing.
Germination was recorded daily until completion, i.e.
one month after the last seed had germinated. Seeds with
a protruding radicle of about 2 mm were considered as
germinated (Figure 1 d). Seedlings with unsplit seed coats
and partially opened or decayed leaves were considered
as ‘abnormal’ (Figure 1 e) and those with fully opened
first pair of leaves and straight stems were considered
‘normal’ (Figure 1 f and g). Ungerminated seeds were
recovered from the soil and their cotyledons examined by
removing the testa to confirm germination failure.
Recovered seeds were placed in 0.1% solution of 2,3,5triphenyl-2H-tetrazolium chloride (TTC) to test for viability29; only viable embryos could turn pink. The seedlings
were transferred to polythene bags (28 cm height, 12 cm
diameter) nearly one month after germination.
Seedling survival was studied periodically at the end of
the rainy season in October (first census), at the end of
the winter season in March (second census), and at the
end of the spring season in May (third census). Seedling
growth was assessed in terms of seedling height, leaf
number and leaf area. Seedling height was measured by a
ruler, the number of leaves was counted, and leaf area
was determined using a leaf area meter (LICOR-3000A).
598
The cause of seedling mortality was ascertained for each
dead seedling (Figure 1 h).
Data analysis
The data were analysed for three seed-weight classes, viz.
< 40 mg (light), ≥ 40–< 80 mg (intermediate) and > 80 mg
(heavy) to interpret the results. Without storage, nearly
50% fresh seeds were in intermediate weight class, 47%
in heavy weight class and only 3% in light weight class.
‘Germination value’, a quantitative index which combines the speed and completeness, was calculated by multiplying germination percentage with the ‘peak value’30.
The peak value is the highest quotient obtained by dividing the cumulative per cent germination on each day by
the number of days elapsed since initial imbibitions.
The differences between means of two groups (oneseeded and two-seeded) were individually determined
using two-tailed Student’s t-test (if n < 30) or z-test (if
n > 30)31. Two-tailed z statistic was used to determine
differences in germination percentages between two samples, and the probabilities calculated following StatSoft32.
The z statistic is given by the equation:
pˆ1 − pˆ 2
,
pˆ1 (1 − pˆ1 ) pˆ 2 (1 − pˆ 2 )
+
n1
n2
z=
where p̂ is the weighted mean (critical ratio) of the two
sampled proportions and is calculated as p̂ = (x1 + x2)/
(n1 + n2); p̂1 and p̂2 the proportions of seeds germinated
in the first and second sample; x1 and x2 the number of
seeds germinated in the first and second sample, and n1
and n2 are the number of seeds sown in the first and second sample.
The Kolmogorov–Smirnov (K–S) test was used to
determine differences between the observed and expected
frequency distribution of seed weights. Germination
curves were drawn by plotting cumulative number of
seeds germinated everyday (y-axis) against germination
time (x-axis) in days. Simple linear regression analysis
was used to determine the relationship between seed
weight and germination time.
Results
Seed packing
In all, 865 fruits were examined. Among these, 821 were
ripe and healthy fruits, 568 were one-seeded and 253
two-seeded, yielding a seed-to-ovule ratio of 0.65.
Among the 44 unhealthy and discarded fruits, 26 were
diseased and 18 unripe.
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RESEARCH ARTICLE
Table 1. Minimum, maximum and mean weight of seeds of Aquilaria malaccensis after no storage, and
5 and 14 days of storage. SE indicates standard error of the mean. Two-tailed z test did not show significant variation in mean seed weight between seeds from one- and two-seeded fruits (values with same
superscript) after no storage (df = 398, P = 0.652), 5 days of storage (df = 398, P = 0.206) and 14 days of
storage (df = 198, P = 0.053)
Seed weight (mg)
Seed number
per fruit
Number of
seeds weighed
Minimum
No storage
One-seeded
Two-seeded
One + two-seeded
200
200
400
31.7
28.8
28.8
129.8
134.8
134.8
78.3 ± 1.67a
79.4 ± 1.77a
78.9 ± 1.22
5 days of storage
One-seeded
Two-seeded
One + two-seeded
200
200
400
18.5
17.1
17.1
97.7
91.1
97.7
46.0 ± 1.34a
48.5 ± 1.50a
47.2 ± 1.01
14 days of storage
One-seeded
Two-seeded
One + two-seeded
125
75
200
12.8
15.9
12.8
88.4
83.4
88.4
33.7 ± 1.38a
38.6 ± 2.36a
35.5 ± 1.24
Seed weight
Fresh seed weight ranged from 29 to 135 mg, which
declined to 17–98 mg after 5 days of storage and 13–88 mg
after 14 days of storage (Table 1). Apparently, seeds lost
considerable weight in storage at room temperature:
40 ± 1.2% by the 5th day and 55 ± 1.5% by the 14th day.
Mean seed weight showed a significant decline from no
storage to 5 days of storage (P < 0.001), and from 5 to 14
days storage (P < 0.001). Two-tailed z-test showed no
difference in mean seed weight between seeds from oneand two-seeded fruits after no storage, and 5 and 14 days
of storage (Table 1).
The frequency distribution of seed weight of fresh
seeds pooled from one- and two-seeded fruits was close
to an expected lognormal distribution (Figure 2 a). However, the distribution became positively skewed after
5 days (Figure 2 b) and highly positively skewed after
14 days of storage (Figure 2 c), presumably due to moisture
loss. When the distribution was compared between seeds
from one- and two-seeded fruits (figures not included),
differences were not significant, indicating that one- and
two-seeded condition had no effect on seed weight.
Seed viability and germination
Germination started on day-13 and was completed by
day-40 for fresh seeds (Figure 3). Similarly, germination
started on day-14 and was completed by day-35 for seeds
stored for 5 days. In both cases, 90% of total germination
was achieved by day-29. Among seeds sown after 14
days of storage, one seed germinated on day-14 and the
other on day-15. Germination value (sensu Czabator30)
CURRENT SCIENCE, VOL. 102, NO. 4, 25 FEBRUARY 2012
Maximum
Mean ± SE
declined from 97.1 for no storage through 85.2 for 5 days
of storage to 6.66 for 14 days of storage.
Seed weight had a strong effect on germination; germination percentages increased with increase in seed weight
(Table 2). Light-weight seeds failed in germination without storage, and after 5 and 14 days of storage. Heavy
seeds showed greater germination percentages than intermediate seeds without storage as well as after 5 days of
storage. After 14 days of storage, only two seeds germinated in the heavy-weight class (Table 2).
Germination percentages declined with increase in
storage time: from 10.5 through 4.3 to no germination for
intermediate seeds, and from 54.8 through 46.5 to only 1
for heavy seeds (Table 2). However, in the heavy-weight
class, fresh seeds from one-seeded fruits showed greater
germination (P < 0.01) than those from two-seeded fruits,
and these differences were not significant after 5 days of
storage. Germination percentage of seeds pooled across
weight classes declined from 31 for no storage through 25
for 5 days to 1 for 14 days of storage.
Seed weight influenced the time to germination; heavier
the seed weight lesser the time needed for germination
(Figure 4). Linear regression of germination time on seed
weight for a pool of seeds from one- and two-seeded
fruits yielded a significant negative correlation after no
storage (Figure 4 a) and 5 days of storage (Figure 4 b).
Because only two seeds germinated after 14 days of storage, a correlation could not be drawn.
Seedling survival and growth
Seedlings from seeds of one- and two-seeded fruits showed
similar patterns of survival after no storage (r = 0.999,
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RESEARCH ARTICLE
df = 2, P < 0.001; Figure 5 a) and 5 days of storage
(r = 0.993, df = 2, P < 0.007; Figure 5 b). Percentage of
seedling survival at the third census was not different between seeds of one- and two-seeded fruits after no storage
(P = 0.503) and 5 days of storage (P = 0.827). No seed
survived by the first census for 14 days of storage (Figure
5 c).
Seed weight influenced survival of seedlings (Figure
6). At the third census, survival as a percentage of the total number of seeds germinated was significantly greater
in the heavy than the intermediate class after no storage
(P = 0.001) and 5 days of storage (P = 0.0005). Survival
percentages did not differ between light and intermediate
classes after 5 days of storage (P = 0.122).
Figure 3. Germination curves for no storage (circle), 5 days of storage (square) and 14 days of storage (cross) after seed collection. Data
for seed germination from one- and two-seeded fruits were pooled for
each storage treatment.
Figure 2. Change in frequency distribution of seed weights of A.
malaccensis from no storage (a) to 5 days of storage (b) and 14 days of
storage (c). The Kolmogorov–Smirnov one-sample D statistic showed
that the observed frequency distribution (bar) deviated from an
expected normal distribution (curve) after no-storage (n = 400,
d = 0.0779, p = 0.05), but assumed a lognormal distribution after 5 days
(n = 400, d = 0.0393, p = ns) and 14 days of storage (n = 200, d = 0.0451,
p = ns). Data for seed weight from one- and two-seeded fruits were
pooled for each storage treatment.
600
Figure 4. Linear relationship between seed weight and germination
time following (a) no storage (y = 40.32–190.38x, df = 122, r = 0.615),
and (b) 5 days of storage (y = 32.32–179.91x, df = 98, r = 0.557) after
collection. Data for 14 days of storage are not shown since only two
seeds germinated resulting in df = 0. Seeds in light (> 0–0.04 g), intermediate (> 0.04–0.08 g) and heavy (> 0.08–0.14 g) weight classes are
separated by vertical grids.
CURRENT SCIENCE, VOL. 102, NO. 4, 25 FEBRUARY 2012
RESEARCH ARTICLE
Table 2. Germination of seeds from one- and two-seeded fruits of A. malaccensis in three seed-weight classes (based on fresh seed weight) on
sowing after no storage, and 5 and 14 days of storage. SE indicates standard error of the mean. Values with different superscripts between one- and
two-seeded categories vary significantly using two-tailed z statistic for two-sample test of percentage (P < 0.05)
Light (> 0–40 mg)
Intermediate weight (> 40–80 mg)
Heavy (> 80–140 mg)
Number
of seeds
sown (n)
Percentage of
seeds germinated
(mean ± SE)
Number
of seeds
sown (n)
Percentage of
seeds germinated
(mean ± SE)
No storage
One-seeded
Two-seeded
One + two-seeded
6
7
13
0.0
0.0
0.0
103
96
199
10.7 ± 3.0a
10.4 ± 3.2a
10.5 ± 2.2
91
97
188
5 days of storage
One-seeded
Two-seeded
One + two-seeded
9
8
17
0.0
0.0
0.0
104
81
185
2.9 ± 2.1a
6.1 ± 1.9a
4.3 ± 1.6
14 days of storage
One-seeded
Two-seeded
One + two-seeded
4
5
9
0.0
0.0
0.0
51
40
91
Seed number
per fruit
Number
Percentage of
of seeds seeds germinated
sown (n)
(mean ± SE)
0.0
0.0
0.0
All weights (> 0–140 mg)
Number
of seeds
sown (n)
Percentage of
seeds germinated
(mean ± SE)
65.9 ± 5.1a
44.3 ± 4.9b
54.8 ± 3.6
200
200
400
35.5 ± 3.3a
26.5 ± 3.3a
31.0 ± 2.3
87
111
198
41.3 ± 9.8a
50.5 ± 8.7a
46.5 ± 7.4
200
200
400
19.5 ± 3.0a
30.5 ± 3.0a
25.0 ± 2.2
45
55
100
0.8 ± 0.9a
1.3 ± 1.2a
1.0 ± 0.7
125
75
200
0.8 ± 0.9a
1.3 ± 1.2a
1.0 ± 0.7
Figure 5. Survival of seedlings of seeds from one-seeded (triangle)
and two-seeded (square) fruits following no storage (a), 5 days of storage (b) and 14 days of storage (c). G depicts the percentage of seeds
germinated, and C1, C2 and C3, depict the percentage of seedlings surviving at the end of the rainy, winter and spring season respectively.
Figure 6. Survival of seedlings raised from seeds from light (diamond), intermediate (square) and heavy (triangle) classes following no
storage (a), 5 days of storage (b) and 14 days of storage (c). G and C1–
C3 are the same as defined in Figure 5.
Seedling growth parameters, viz. seedling height,
leaf number and leaf area increased with seedling age, i.e.
from the first to second, and second to third census
both in intermediate and heavy seed classes after no
storage and 5 days of storage (Figure 7). No seedling
from light seeds and no seedling from 14 days of
stored seeds survived. One-way analysis of variance
showed significant effect of storage time, seed weight
and growth period on seedling growth parameters, i.e.
significantly greater growth of seedlings: from fresh than 5
days stored seeds, from heavy than intermediate seeds,
and for the second and third censuses than at the
first census (Table 3). Seedling growth between the second and the third censuses did not vary significantly
(P > 0.05).
Discussion
CURRENT SCIENCE, VOL. 102, NO. 4, 25 FEBRUARY 2012
Seed packing in tropical plants can vary due to seed
abortion33,34. In A. malaccensis, two-third of the fruits
produced only one seed from the two ovules housed in a
bilocular ovary. The maternal parent is known to favour
abortion to gain dispersal advantage if the fruit is a dispersal unit as in many leguminous pods34,35. In A. malaccensis, dispersal is passive with seeds dropping to the
ground after dehiscence of the capsule35, or may be mediated by wind as the seeds are tiny though not designed for
wind dispersal. Hence, seed abortion in anticipation of
dispersal advantage is unlikely.
Seed abortion may occur due to a trade-off between
maternal and offspring interests. The most economic use
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RESEARCH ARTICLE
Table 3. Probabilities obtained from one-way analysis of variance to determine the effect of seed storage time (no storage and 5 days of storage), seed weight (intermediate and heavy), and growth period
(censuses 1–3) on seedling growth parameters of A. malaccensis. Data were analysed for only those seedlings that had at least one leaf present. Seedlings from 14 days of storage treatment and from light-weight
class died before the first census; hence these treatments were excluded from the analyses
P level
Source of variation
Degrees of freedom
Seedling height
Leaf number
Leaf area
Storage time
Error
1
312
0.195
0.023
0.028
Seed weight
Error
1
312
0.001
0.000
0.000
Growth period
Error
2
311
0.000
0.000
0.000
Figure 7. Effect of seed weight and storage time on seedling growth parameters, viz. seedling height
(bricks), leaf number (hatch) and leaf area (horizontal line) at the time of the first (C1), second (C2) and
third (C3) census. Data were averaged for only those seedlings that had at least one leaf present. Table 3
shows the results of analysis of variance for the data.
of maternal resources is attained by packing as many
seeds as possible in order to reduce the cost of packing
per seed34. However, seed size may be negatively influenced with increasing packing of seeds per fruit as in
Mesua ferrea, where heavier seeds germinate better and
their seedlings grow and survive better than lighter
seeds36. Thus, a trade-off between the packing cost and
offspring performance may guide the species to optimize
seed number per fruit by inducing abortion, particularly
where seed size is dependent on the seed number per
fruit. Seed abortion may simply result from the failure of
fertilization or pollination. Regardless of the cause of
abortion of one of the two seeds in the fruit of A. malaccensis, the range of variation in seed weight, mean seed
weight and frequency distribution of seeds in seed-weight
classes were not significantly different between the seeds
from one- and two-seeded fruits. Further, as seeds develop
602
in separate locules with equal probability of resource
supply due to symmetrical architecture of the locules,
seed size and shape (length, width and volume) do not
vary significantly between the seeds from one- and twoseeded fruits. Conclusively, the seeds from one-seeded
fruits are not heavier than those from two-seeded fruits in
A. malaccensis.
Notwithstanding, the heavy seeds germinated faster
than the light seeds. Greater and faster germination of
heavier seeds has been reported in many tropical species37–43. However, contradictory results have been
reported in many other species36,44–46, and germination
may be independent of seed weight in some species47,48.
Heavy seeds may simply out-compete light seeds, since
the latter may house underdeveloped or unhealthy embryos.
Seed weight strongly influenced seedling survival and
growth. Seedlings from heavy seeds survived maximally
CURRENT SCIENCE, VOL. 102, NO. 4, 25 FEBRUARY 2012
RESEARCH ARTICLE
and produced more height, leaf number and leaf area than
those from intermediate seeds. The growth of the seedlings was faster between the first and the second censuses
(interval of 5 months) compared to that between the second and third censuses (interval of 2 months).
On storage, the frequency distribution of seed weight
increases positive skewness, apparently due to a rapid
loss of moisture from seeds (40% by the 5th day and 55%
by the 14th day). Although mean seed weight declines on
storage due to loss of moisture, the difference between
the mean weights of seeds from one- and two-seeded
fruits remains insignificant, indicating that seed number
per fruit has no effect on the rate of moisture loss.
Seed weight and storage time influenced germination
strongly. Freshly sown, heavy seeds showed maximum
germination, but light seeds failed to germinate completely. With storage for 5 days, heavy seeds exhibited more
germination than intermediate seeds, and light seeds did
not germinate again. Finally, with storage for 14 days, all
seeds except two failed to germinate. The two germinated
seeds were from the heavy-weight class and they died
quickly after germination. Hence, overall germination
percentage declined from no storage to 5 days of storage
and finally to 14 days of storage. Beniwal27 found 65%
germination when selectively picked, ‘healthy’ seeds were
sown. It is believed that storing seeds in cool conditions
such as in a refrigerator may prolong viability up to 30
days49.
Seed storage time influenced seedling growth, which
was better from freshly sown than 5 days of stored seeds.
There was no seedling from light seeds, and all seedlings
from intermediate seeds sown after 5 days of storage had
died. Thus, it could be recommended that only heavy
seeds (preferably over 80 mg fr. wt.) be sown quickly
after collection to maximize germination and survival.
In A. malaccensis, non-endospermic seeds mature in
the middle of the rainy season when plenty of moisture is
available, and predators are abundant to cause damage to
the seeds. In this climatic setting, seeds maximize germination by germinating soon after dispersal instead of
remaining dormant through the ensuing winter. Therefore, short viability helps this species to capitalize on
moisture availability for germination in the same growth
season and minimize pressure for investing energy into
the seeds to sustain through winter.
Conclusion
This study reveals that seed abortion in A. malaccensis
gives rise to one-seeded versus two-seeded fruits, but the
varied number of seeds per fruit does not influence seed
weight, as one would expect. However, seed weight
strongly influenced germination time and percentage,
seedling survival and seedling growth. The seeds are sensitive to desiccation in storage and may result in loss of
CURRENT SCIENCE, VOL. 102, NO. 4, 25 FEBRUARY 2012
viability and germination as well as in slower growth of
seedlings. Short viability enforces germination during the
rainy season and excludes the need to store energy in the
seeds for maintenance.
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ACKNOWLEDGEMENTS. The experimental work was done at the
North-East Unit of the G.B. Pant Institute of Himalayan Environment
and Development, Itanagar. I acknowledge partial funding from DBT,
New Delhi (grant # BT/PR7928/NDB/52/9/2006), facilities afforded at
the Department of Botany, North-Eastern Hill University, Shillong, and
help received from Shilpi Agarwal during the experiment and Dr K.
Haridasan in species identification.
Received 26 October 2010; revised accepted 23 January 2012
CURRENT SCIENCE, VOL. 102, NO. 4, 25 FEBRUARY 2012