Content uploaded by Patricia Berjak
Author content
All content in this area was uploaded by Patricia Berjak on Sep 25, 2014
Content may be subject to copyright.
Seed behaviour in Phoenix reclinata Jacquin, the wild
date palm
Gundula T. von Fintel, Patricia Berjak* and N.W. Pammenter
School of Biological and Conservation Sciences, University of KwaZulu-Natal§, Durban, 4041 South Africa
Abstract
Despite the importance of the palm family, Arecaceae,
little has been systematically documented about the
seed behaviour of the many species. The post-harvest
seed behaviour of Phoenix reclinata, the highly utilized
wild date palm species distributed along the eastern
seaboard of Africa, is investigated in the present study.
While both embryo and endosperm water concentration
declined as the seeds of Phoenix reclinata matured, they
remained relatively high: this is a characteristic of (but
not confined to) non-orthodox seeds. The ultrastructure
of embryo cells, and the finding that negligible water
uptake was required for the initiation of germination,
were in keeping with the possible non-orthodox nature of
the seeds. A developmental study revealed that between
the acquisition of full germinability and complete pre-
shedding maturity, germination performance appeared to
be constrained, suggesting the presence of an inhibitor.
Pre-treatment by soaking, mechanical or acid
scarification had no significant promotory effect on either
rate or totality of germination of mature P. reclinata
seeds, while use of water transiently at 100°C was highly
deleterious. However, germination of partially dehydrated
seeds was initiated sooner if they had been soaked or
scarified. Mature P. reclinata seeds tolerated dehydration
to a mean embryo water concentration of 0.40 g g1(dry
mass basis; dmb), but at 0.14 g g1, both rate and totality
of germination were adversely affected. However,
viability of seeds dehydrated to the mean embryo water
concentration 0.40 g g1declined during storage for 16
weeks. It is concluded that P. reclinata seeds are non-
orthodox, and are best categorized as showing
intermediate post-harvest behaviour.
Keywords: Arecaceae, intermediate, orthodox, palm, Phoenix
reclinata, post-harvest behaviour, recalcitrant seeds
Introduction
There are around 200 genera of palms worldwide
(Uhl and Dransfield, 1987), of which only 19 are
native to Africa and five to South Africa (Tuley, 1995).
Wherever palms occur, they are very heavily utilized,
leading to the estimation that half the species could
face global extinction within the next 50–100 years
(Smith et al., 1993), and consequently to the need for
establishment of extensive conservation projects
(Maunder et al., 2001). However, such projects will
require knowledge of palm seed storage behaviour
and germination characteristics, which is presently
lacking (Davies and Pritchard, 1998a).
Seeds are categorized as orthodox or non-
orthodox in post-harvest behaviour, based upon the
degree of desiccation they will tolerate. Additionally,
there are various species with seeds that are relatively
desiccation tolerant, although less so than orthodox
types. Such seeds, which may be chilling sensitive,
especially after dehydration, have been described as
exhibiting intermediate storage behaviour (Hong and
Ellis, 1996). Although this categorization of seed types
is considered an over-simplification (Pammenter and
Berjak, 1999), it will be used here for convenience.
It is generally recommended (e.g. Wicht, 1969;
Donselman, 1982; Meerow, 1991) that palm seeds
should be planted fresh, as viability is lost within a
relatively short time. According to Broschat (1994)
seeds of many palm species lose viability within 3–6
weeks of harvest, due to the deleterious effects of
desiccation.
Various procedures promote palm seed germi-
nation, including removal of the fruit tissue (Rauch et
Seed Science Research (2004) 14, 197–204 DOI: 10.1079/SSR2004169
*Correspondence
Email: berjak@ukzn.ac.za
§Formerly University of Natal
al., 1982; Broschat and Donselman, 1986, 1987;
Meerow, 1991; Rauch, 1994; Ehara et al., 2001),
soaking, hot-water scarification, use of growth
regulators and mechanical scarification. However, the
outcomes of soaking trials have been equivocal.
Increases in germination rate and extent have been
recorded for Archontophoenix alexandrae (Nagao and
Sakai, 1979; Nagao et al., 1980; Odetola, 1987),
Chrysalidocarpus lutescens (Odetola, 1987; Maciel de
Sousa, 1995), Phoenix dactylifera (Odetola, 1987),
Hyphaene thebaica (Davies and Pritchard, 1998b;
Moussa et al., 1998), H. petersiana and Medemia argun
(Davies and Pritchard, 1998b), Rhapidophyllum hystrix
(Carpenter et al., 1994), Chamaedorea seifrizii (Rauch,
1994) and Roystonea oleraceae (Maciel, 2001). In other
instances, seed soaking has been ineffective, e.g.
Arecastrum romanzoffianum and Roystonea regia
(Broschat and Donselman, 1987), Dictyosperma aureum
and Verschaffeltia splendida (Odetola, 1987). Loomis
(1958) found that hot-water scarification (100°C,
3 min), followed by soaking for 2–3 weeks, was
beneficial to the germination of Acrocomia sclerocarpa
and Astrocaryum mexicanum.
Mechanical scarification promotes germination of
a variety of palms, especially where the seed coat is
hard. Success has been recorded for Rhapidophyllum
hystrix (Carpenter et al., 1994), Phoenix roebelenii
(Doughty et al., 1986), Archontophoenix alexandrae and
Ptychosperma macarthurii (Nagao et al., 1980), and
other species, including Hyphaene schatan, Phoenix
acaulis and Sabal palmetto (Odetola, 1987).
In general, mature palm seeds exhibit the best
overall germination performance (Rauch et al., 1982;
Broschat and Donselman, 1987; Broschat, 1994; Maciel
de Sousa, 1995; Silva et al., 1999). However, in some
species, germination rates are higher for pre-mature
seeds, but the overall germination percentages were
superior once the seeds were mature (Broschat and
Donselman, 1987; Maciel, 2001). These authors
suggested that this may be due to an inhibitor in the
mature fruit tissue. Alternatively in such cases,
increased hardening of the seed coat with maturity
may be a contributing factor.
Phoenix seeds are considered as orthodox (P.
dactylifera) or probably orthodox [P. canariensis, P.
rupicola, P. sylvestris and P. reclinata (Tweddle et al.,
2003)]. The uncertainty about palm seed
categorization generally reflects gaps in the
information about seed water concentrations at
shedding, storage parameters and seed survival in
storage, as well as germination characteristics and
conditions.
Phoenix reclinata Jacquin was chosen for the present
study, the first investigation of the post-harvest seed
behaviour of any South African palm species. P.
reclinata occurs naturally along the eastern seaboard
of Africa, extending into Egypt (Pooley, 1993). It is
mainly riverine in distribution, where the root system
plays an important part in bank stabilization, and
occurs also in the brackish-water regions adjacent to
mangrove forests (Wicht, 1969; the authors’ personal
observations), but it also grows in open savannah.
The species is heavily utilized throughout Africa, and
the fruits are eaten by a wide range of animals (Wicht,
1969; Pooley, 1993). Although not presently
endangered, the demands made on the species are
such that this may not always be the case. Although
Hong and Ellis (1996), and comments made by
Mbuya et al. (1994), suggest the seeds to be orthodox,
this may not be the case, as confirmatory data are not
available. The present contribution reports on
germinability of seeds of differing maturity status, the
effects of various pre-treatments on germination, seed
responses to dehydration and survival in storage at
various water concentrations.
Materials and methods
Fruits and seeds
The ripening fruits of P. reclinata pass from green
through green–yellow to yellow, orange and brown
when fully ripe. Fruits at these developmental stages
were collected in the vicinity of Durban, enclosed in
plastic bags and immediately brought to the
laboratory, where they were stored at 16°C for no
longer than 1 week. Immediately before use, seeds
were extracted manually and cleaned of all fruit pulp.
The coats of seeds from orange and brown fruits were
darker and harder than those from fruits in the green
through to yellow maturity stages, although all were
of a similar seed and embryo size. For convenience,
developmental (or maturity) status of seeds is
described in relation to fruit colour as 1 (green), 2
(green–yellow), 3 (yellow), 4 (orange) and 5 (brown,
mature).
Initial seed lot characteristics
Water concentration was determined gravimetrically
for individual embryos excised from 20 seeds per
assessment, for endosperm segments from fresh seeds
and immediately after dehydration to individual
target moisture contents (see below). Wet and dry
mass was determined after oven-drying to constant
weight at 80°C. Data are recorded as g H2O (g dry
mass)
1(g g
1).
Fifteen seeds per fruit maturity stage, or 20 seeds
that had been dehydrated to each of a series of water
concentrations, were surface sterilized by immersion
in 1% sodium hypochlorite for 10 min, and set to
germinate on 1% water agar in sterile Petri dishes, at
29°C with a 14 h photoperiod in a controlled
198 G.T. von Fintel et al.
environment cabinet. Seeds were monitored daily for
50 d, and germination scored as positive upon radicle
emergence.
Germination pre-treatments
Batches of 20 fresh, mature seeds (from brown fruits)
and 20 that had been dehydrated to an embryo water
concentration of 0.21 g g
1were subjected to one of
the following pre-treatments: soaking in aerated
water at ambient temperature (~25°C) for 3 d;
scarification with water briefly at 100°C, which was
left to cool to ambient temperature, followed by
soaking (in the same water) for 3 d; mechanical
scarification; acid scarification using 0.1 M HCl for
10 h and an untreated control. Immediately after the
various pre-treatments, seeds were surface-sterilized
and set to germinate as described above.
Desiccation
Batches of 320 weighed mature seeds were
thoroughly mixed with an equal weight of activated
silica gel within sealed, heavy-duty, polythene bags
that were maintained at ambient temperature. The
silica gel was exchanged in all the bags at the first
sign of a change of the indicator colour. Equivalent
seed batches were mixed with dry vermiculite and
similarly maintained as the control material.
Individual seed batches subjected to desiccation were
weighed at intervals until a collective mass,
predetermined by the target moisture content (TMC)
equation (IPGRI/DFSC, 1999), was achieved. Seeds
were removed for experimentation or storage at each
of a declining series of TMCs, prior to which the
actual water concentration of individual embryos and
endosperm segments was determined and
germination performance assessed.
Storage
Experimental and control seed batches were dusted
with a fungicide (Benomyl 500 WP, Dow
AgroSciences, Pretoria, South Africa) and stored in
air-tight containers at 16°C for various time intervals.
A sub-set of seeds at the initial water concentration
was stored at 6°C. Seeds were sampled periodically
over 22 or 16 weeks (control and variously
dehydrated samples, respectively) for water content
determination, rate of imbibition and assessment of
germination performance.
Electron microscopy
After immersion in water for 15 min, embryos were
excised from non-dehydrated seeds, processed
routinely through phosphate-buffered glutaraldehyde,
aqueous osmium tetroxide and a graded acetone
series, after which they were embedded in a low-
viscosity, epoxy resin. Ultrathin sections were post-
stained with uranyl acetate and lead citrate, and
examined with a JEOL JEM 1010 transmission electron
microscope (JOEL Ltd, Tokyo, Japan).
Statistical analysis
Water concentration data were analysed by one-way
analysis of variance, using the SPSS statistical analysis
programme (version 9.0.1, SPSS Inc., Chicago, Illinois,
USA); as the data were normally distributed, they
were not transformed prior to analysis. In cases where
analysis of variance indicated a significant treatment
effect, Tukey’s multiple range test was used to
identify homogeneous groups (Sokal and Rohlf,
1981). Where appropriate, germination data were
subjected to 2tests.
Results and discussion
Initial seed-lot characteristics
The mean water concentration of the embryos
remained essentially constant as seeds matured to
stage 3, but declined significantly by stage 4 (P<
0.05). In contrast, endosperm water concentration was
similar at stages 1 and 2, declined by stage 3 (P< 0.05)
and thereafter did not decline significantly (Fig. 1). A
differential between embryo and endosperm water
concentrations was a consistent feature during seed
development in P. reclinata, and even at maturity, the
embryo tissues remained considerably more
hydrated, at a mean of 1.5 g g
1, than the endosperm
(c. 0.5 g g
1). The proportional decline in water
concentration from stages 1 to 5 of the two tissues was
essentially the same (embryos, 34.7%; endosperm,
32.4%).
The fruits of P. reclinata are naturally shed once the
exocarp has browned, and the pulp is still hydrated
and fleshy. Hence, seeds at stage 5, presently removed
from hand-harvested fruits in this condition, are
assumed to have completed maturation. While some
seed dehydration may occur after fruit abscission,
embryo and endosperm water concentrations of stage
5 seeds are consistent with the seeds being non-
orthodox. This is supported by the ultrastructure of
axis cells, which, although showing a degree of
intracellular dedifferentiation relative to stage 2,
(compare Figs 2a and 2b, c) did not present typical
features of the mature, orthodox condition (e.g. Klein
and Pollock, 1968).
Seeds of developmental stages 2–5 initiated
germination within 10 d, the lag period being the
shortest (7 d) for stages 2 and 3 (Fig. 3). Stage 1 seeds,
Seed behaviour of wild date palm 199
extracted from green fruits, were clearly immature,
with only 27% germination and 31 d elapsing before
first radicle protrusion. While seeds of developmental
stages 2 and 5 germinated at essentially the same rate
(T50 = 12 and 14 d, respectively) and achieved the
same final germination (87%), those harvested in
developmental stages 3 and 4 germinated less rapidly,
with stage 3 seeds showing only 60% total
germination. This trend was confirmed in trials with
seeds harvested the following year (data not shown).
While it is presently not possible to account for
these observations, a possible explanation may be that
a temporary physiological block develops between
the time that the seeds acquire full germinability
(stage 2) and when they are fully mature (stage 5).
This view is supported by the indication that
germination rate is also adversely affected at stage 4,
although the overall effect on germination is not as
extreme as for stage 3 seeds. As the seeds were
presently cleaned of all fruit tissue, this cannot be
ascribed to immediate inhibitory effects of factors in
the fruit pulp in P. reclinata, as has been suggested for
other palm species by a variety of authors (Rauch et
al., 1982; Broschat and Donselman, 1986, 1987;
Meerow, 1991; Rauch, 1994; Ehara et al., 2001).
Furthermore, it is difficult to argue that the seed coat
imposes this postulated block, as germination rate
and totality were essentially similar for stage 5 seeds,
where the testa had become harder and had browned,
and for stage 2 seeds, with a softer coat. This leaves
the embryo itself, the endosperm, or the interaction of
200 G.T. von Fintel et al.
0.0
1.0
2.0
3.0
012345
Maturity stage
Water concentration (g g
–1
)
AA
A
BB
aab
bb
Figure 1. Water concentrations in embryos (closed symbols)
and endosperm (open symbols) of Phoenix reclinata seeds of
different maturity stages. Error bars show 95% confidence
intervals. Letters indicate homogeneous groups in embryo
(upper case) and endosperm (lower case) water
concentrations (ANOVA, F4–101 = 36.26, P< 0.05 for embryos,
and F4–67 = 26.69, P< 0.05 for endosperm; homogeneous
groups from Tukey’s multiple range test).
Figure 2. Ultrastructure of the radicle meristem cells of
Phoenix reclinata seeds at (a) developmental stage 2, and (b
and c) developmental stage 5. Plastids (P), in particular, had
not dedifferentiated significantly at stage 5 relative to stage
2. Polysomes (arrowheads) are also evident at both stage 2
and stage 5. Bars, 0.2 µm.
the cotyledon with the endosperm as possible
locations where the block might be sought. The
ultrastructure of the axis of stage 3 seeds was that of
highly metabolically active cells (data not shown),
and so provides no explanation of the differences in
germination performance of the earlier and later
developmental states of the seeds.
Pre-treatments
Except where indicated, all pre-treatments were
applied to hydrated, stage 5 seeds. At the initial mean
embryo water concentration of 1.58 g g
1, the time to
first radicle protrusion, germination rate and totality
were not significantly different for untreated seeds, or
those that were mechanically or acid scarified, or
soaked for 3 d at ambient temperature (soaking time
was included in the germination time) (Fig. 4).
Application of water transiently at 100°C, followed by
soaking the seeds for 3 d in the same water after
cooling, had markedly deleterious effects in terms of
the lag phase, and rate and totality of germination.
Additionally, fungal proliferation, emanating from
within the seed tissues, was a common feature of
seeds subjected to this treatment. While association of
fungi was generally noted during germination
assessment of the P. reclinata seeds, whether pre-
treated or not, in no other case did the mycoflora
proliferate extensively. Both vigorous germinating
orthodox seeds (Berjak, 1996) and non-orthodox seeds
have mechanisms to counteract the proliferation of
fungi, which fail when the seeds become debilitated
(Anguelova-Merhar et al., 2003), and there can be little
doubt that treatment with near-boiling water did
debilitate the P. reclinata seeds.
The germination data for P. reclinata seeds,
dehydrated to a mean embryo water concentration of
0.21 g g
1prior to the various pre-treatments, are
shown in Fig. 5. Immersion in water at 100°C was
considerably more deleterious after desiccation, than
when the seeds had not been dehydrated. While no
differences in germination parameters were apparent
for dehydrated seeds that received no pre-treatment
and those that were soaked (3 d) or acid scarified,
those that had been mechanically scarified initiated
germination more rapidly.
Successful hot-water scarification, as reported by
Loomis (1958) for Acrocomia sclerocarpa and
Seed behaviour of wild date palm 201
0
20
40
60
80
100
0 1020304050
Days after planting
% Germination
Figure 3. Time course of germination of Phoenix reclinata at
different maturity stages: , stage 1; ▫, stage 2; , stage 3;
, stage 4; ●, stage 5.
0
20
40
60
80
100
0 1020304050
Days after planting
% Germination
Figure 4. Time course of germination of seeds of Phoenix
reclinata at the initial shedding water concentration after a
variety of pre-treatments: , no treatment; ▫, soak; , HCl;
●, boil; , scarification.
0
20
40
60
80
100
0 1020304050
Days after planting
% Germination
Figure 5. The effects of various pre-treatments on the
germination time course of Phoenix reclinata seeds that had
been previously dehydrated to a water concentration of
0.21 g g
1. , no treatment; ▫, soak; , HCl; ●, boil;
, scarification.
Astrocaryum mexicanum, may not be deleterious if the
palm seeds are thick-coated and are orthodox. The
embryos in newly harvested non-orthodox seeds at
high embryo water concentration are highly likely to
be active metabolically, and the ultrastructure (Fig. 2)
suggested this to be the case for P. reclinata seeds.
Embryos would be highly vulnerable to high
temperatures in this condition.
Phoenix reclinata seeds at the initial water
concentration (embryo, 1.58 g g
1; endosperm,
~0.5 g g
1) took up only 3% of their initial mass in
water during imbibition over 10 d, and only after
dehydration to a mean embryo water concentration of
0.21 g g
1was water uptake increased by c. 35%
during this period (data not shown). This is a further
indicator that these seeds are non-orthodox. The fact
that neither mechanical, nor acid, scarification had
any significant promotive effects on the germination
of the stage 5 P. reclinata seeds at the initial water
concentration, argues that the seed coat presents no
barrier to radicle protrusion in this species. The
slightly beneficial effects of mechanical scarification of
the seeds after they had been dehydrated suggests
that, as it dries down, the coat does slow the ingress
of water and/or present a slightly more challenging
barrier for radicle protrusion. However, even without
any pre-treatment, seeds dehydrated to an embryo
water concentration of 0.21 g g
1germinated readily,
reinforcing the idea that the coat is not a major
impediment for germination in P. reclinata seeds.
Desiccation
Mature (stage 5) seeds of P. reclinata were dehydrated
by burial in silica gel for a total of 16 d. The decline in
embryo water concentration was rapid over the first
2 d, declining gradually by the twelfth day, and
remaining relatively constant thereafter. Endosperm
water concentration declined to about half the initial
value in the first 24 h, and then very gradually to day
16. Seeds were sampled at four TWCs, corresponding
to embryo water concentrations of 1.14, 0.51, 0.40 and
0.14 g g
1. When seeds were immediately planted
after dehydration, the impact of drying was reflected
in the germination rate, which was slower in all cases
relative to the rate at which seeds germinated at the
initial water concentration (Fig. 6). Nevertheless, total
germination was essentially similar for seeds at the
initial water concentration and those dehydrated to
the range 1.14–0.40 g g
1. The reduction in
germination rate may have been a consequence of
desiccation damage or because the partially dried
seeds required longer to imbibe. However, there was
a significant decline in germinability (P< 0.01; 2test)
and an increased germination lag of the seeds dried to
0.14 g g
1(Fig. 6).
It took 12 d for water concentrations in both the
embryo and endosperm to decline to 0.14 g g
1. Were
the seeds of P. reclinata orthodox, the marked decline
in vigour and viability accompanying this
dehydration regime would not be expected. These
responses of P. reclinata seeds suggest that they are
intermediate, sensu Hong and Ellis (1996).
Seed storage
Seeds at the initial embryo water concentration were
stored at 16°C for a total of 22 weeks and those
dehydrated to the levels indicated above for 16
weeks, there being insufficient material for longer
storage trials (Fig. 7). The trends reported for viability
immediately after dehydration from embryo water
concentrations of 1.58 to 0.51 g g
1were retained
throughout the storage period. However, viability of
seeds stored at an embryo water concentration of
0.40 g g
1declined significantly, compared with
values immediately after dehydration (P< 0.01, 2
test), despite their unimpaired germination totality
when set out on water agar immediately after
dehydration. The condition of seeds dehydrated to
the embryo water concentration of 0.14 g g
1declined
steadily and significantly (P< 0.01, 2test) (Fig. 7).
Cold storage had adverse effects on P. reclinata seeds;
viability of seeds stored at 4°C for 12 weeks (58%) was
significantly lower (P< 0.01, 2test) than that of seeds
stored at 16°C for the same period (86%). Shortage of
material precluded assessment of the effects of low
temperature on seeds after dehydration.
202 G.T. von Fintel et al.
0
20
40
60
80
100
0 1020 304050
Days after planting
% Germination
Figure 6. Germination time course of seeds of Phoenix
reclinata that had been dried to a range of water
concentrations: , 1.58 g g
1; ▫, 1.14 g g
1; , 0.51 g g
1; ,
0.40 g g
1; ●, 0.14 g g
1. Total germination percentages at the
end of the experiment differed among dehydration
treatments (2 = 19.05, df = 4, P< 0.01).
The present results indicate that seeds of P.
reclinata are neither orthodox nor recalcitrant, but
show intermediate post-harvest behaviour, as defined
by Hong and Ellis (1996). Although surviving with
unabated vigour and viability for 22 weeks when
stored at 16°C at the original (shedding) water
concentration, dehydration to embryo water
concentrations below 0.4 g g
1adversely affects these
seeds. For plants occurring in the riparian zone, this
degree of desiccation sensitivity may be unimportant
in terms of seed survival and germination. However,
unless seed shed coincides with the wet season, the
lack of desiccation tolerance may impose constraints
on reproduction via seed in open savannahs.
These findings further illustrate that there is a
diverse range of post-harvest seed behaviour in the
palm family, as the data compiled by Tweddle et al.
(2003) indicate, highlighting the need for further
investigations into this highly utilized family.
References
Anguelova-Merhar, V. S., Calistru, C. and Berjak, P. (2003)
A study of some biochemical and histopathological
responses of wet-stored recalcitrant seeds of Avicennia
marina infected by Fusarium moniliforme. Annals of Botany
92, 1–8.
Berjak, P. (1996) The röle of micro-organisms in
deterioration during storage of recalcitrant and
intermediate seeds. pp. 121–126 in Poulsen, K.;
Stubsgaard, F.; Ouédraogo, A.S. (Eds) Improved methods
for the handling and storage of intermediate/recalcitrant forest
tree seeds. Rome, International Plant Genetic Resources
Institute.
Broschat, T.K. (1994) Palm seed propagation. Acta
Horticulturae 360, 141–147.
Broschat, T.K. and Donselman, H. (1986) Factors affecting
the storage and germination of Chrysalidocarpus lutescens
seeds. Journal of the American Society for Horticultural
Science 111, 872–877.
Broschat, T.K. and Donselman, H. (1987) Effects of fruit
maturity, storage, presoaking, and seed cleaning on
germination in three species of palms. Journal of
Environmental Horticulture 5, 6–9.
Carpenter, W.J., Ostmark, E.R. and Ruppert, K.C. (1994)
Promoting the germination of needle palm seed.
Proceedings of the Florida State Horticultural Society 106,
336–338.
Davies, R.I. and Pritchard, H.W. (1998a) Seed conservation
of dryland palms of Africa and Madagascar: needs and
prospects. Forest Genetic Resources 26, 37–44.
Davies, R.I. and Pritchard, H.W. (1998b) Seed storage and
germination of the palms Hyphaene thebaica, H. petersiana
and Medemia argun. Seed Science and Technology 26, 823–828.
Donselman, H. (1982) Palm seed germination studies.
Proceedings of the Florida State Horticultural Society 95,
256–257.
Doughty, S.C., O’Rourke, E.N., Barrios, E.P. and Mowers,
R.P. (1986) Germination induction of pygmy date palm
seed. Principes 30, 85–87.
Ehara, H., Morita, O., Komada, C. and Goto, M. (2001)
Effect of physical treatment and presence of the pericarp
and sarcotesta on seed germination in sago palm. Seed
Science and Technology 29, 83–90.
Hong, T.D. and Ellis, R.H. (1996) A protocol to determine seed
storage behaviour. IPGRI Technical Bulletin No. 1. Rome,
International Plant Genetic Resources Institute.
IPGRI/DFSC (1999) Desiccation and storage protocol.
pp. 23–39 in The project on handling and storage of
recalcitrant and intermediate tropical forest seeds,
Newsletter No. 5. Rome, IPGRI/DFSC.
Klein, S. and Pollock, B.M. (1968) Cell fine structure of
developing lima bean seeds related to seed desiccation.
American Journal of Botany 55, 658–672.
Loomis, H.F. (1958) The preparation and germination of
palm seeds. Principes 2, 98–102.
Maciel, N. (2001) Emergence of royal palm seedlings
(Roystonea oleraceae [Jacq.] O.F. Cook) as affected by fruit
and seed treatments. Bioagro 13, 105–110.
Maciel de Sousa, N. (1995) Effects of maturity, storage and
fermentation of the fruit on emergence in areca palm
(Chrysalidocarpus lutescens). Proceedings of the
Interamerican Society for Tropical Horticulture 39, 69–73.
Maunder, M., Lyte, B., Dransfield, J. and Baker, W. (2001)
The conservation value of botanic garden palm
collections. Biological Conservation 98, 259–271.
Mbuya, L.P., Msanga, H.P., Ruffo, C.K., Birnie, A. and
Tengnäs, B. (1994) Useful trees and shrubs for Tanzania.
Nairobi, Kenya, SIDA Regional Soil Conservation Unit.
Meerow, A.W . (1991) Palm seed germination. Institute of Food
and Agricultural Sciences, University of Florida
Cooperative Extension Service Bulletin 274. Gainesville,
University of Florida.
Seed behaviour of wild date palm 203
0
20
40
60
80
100
0 5 10 15 20
Weeks in storage
% Germination
Figure 7. Total germination percentage of seeds of Phoenix
reclinata stored at 16°C after initial drying to a range of water
concentrations: , 1.58 g g
1; ▫, 1.14 g g
1; , 0.51 g g
1;
, 0.40 g g
1; ●, 0.14 g g
1. There was a significant difference
in germination between the start and end of the storage
period for seeds at a water concentration of 0.40 g g
1(2 =
13.27, df = 1, P< 0.01) and of 0.14 g g
1(2 = 9.52, df = 1, P<
0.01).
Moussa, H., Margolis, H.A., Dube, P.A. and Odongo, J.
(1998) Factors affecting the germination of doum palm
(Hyphaene thebatica Mart.) seeds from the semi-arid zone
of Niger, West Africa. Forest Ecology and Management 104,
27–41.
Nagao, M.A. and Sakai, W.S. (1979) Effect of growth
regulators on seed germination of Archontophoenix
alexandrae. HortScience 14, 182–183.
Nagao, M.A., Kanegawa, K. and Sakai, W.S. (1980)
Accelerating palm seed germination with gibberellic
acid and bottom heat. HortScience 15, 200–201.
Odetola, J.A. (1987) Studies on seed dormancy, viability and
germination in ornamental palms. Principes 31, 24–30.
Pammenter, N.W. and Berjak, P. (1999) A review of
recalcitrant seed physiology in relation to desiccation-
tolerance mechanisms. Seed Science Research 9, 13–37.
Pooley, E. (1993) The complete guide to trees of Natal, Zululand
and Transkei. Durban, South Africa, Natal Flora
Publications Trust.
Rauch, F.D. (1994) Palm seed germination. International
Plant Propagators’ Society: Combined Proceedings 44,
304–307.
Rauch, F.D., Schmidt, L. and Murakami, P.K. (1982) Seed
propagation of palms. International Plant Propagators’
Society: Combined Proceedings 32, 341–347.
Silva, M.A.S., Castellani, E.D. and Demattê, M.E.S.P. (1999)
Effect of fruit maturation stage and light on seed
germination of Aiphanes aculeata. Acta Horticulturae 486,
229–231.
Smith, F.D.M., May, R.M., Pellew, R., Johnson, T.H. and
Walter, K.S. (1993) Estimating extinction rates. Nature
364, 494–496.
Sokal, R.R. and Rohlf, F.J. (1981) Biometry. The principles and
practice of statistics in biological research. San Francisco,
W.H. Freeman and Company.
Tuley, P. (1995) The palms of Africa. Cornwall, Trendrine
Press.
Tweddle, J.C., Turner, R.M. and Dickie, J.B. (2003) Seed
information database (release 5.0, July 2003). Available
at http://www.rbgkew.org.uk/data/sid.
Uhl, N.W. and Dransfield, J. (1987) Genera Palmarum: A
classification of palms based on the work of Harold E. Moore
Jr. Lawrence, Kansas, Allen Press.
Wicht, H. (1969) The indigenous palms of southern Africa. Cape
Town, Howard Timmins.
Received 29 August 2003
accepted after revision 18 February 2004
© CAB International 2004
204 G.T. von Fintel et al.
