Seed germination characteristics of Phillyrea angus

12 Pages·2015·0.23 MB·English

Ann. For. Res. 58(1): 27-37, 2015 ANNALS OF FOREST RESEARCH
DOI: 10.15287/afr.2015.304 www.afrjournal.org
Seed germination characteristics of Phillyrea angus-
tifolia L. and P. latifolia L. (Oleaceae), two Mediterra-
nean shrub species having lignified endocarp
S. Mira, L. Veiga-Barbosa, F. Pérez-García
Mira S., Veiga-Barbosa L., Pérez-García F., 2015. Seed germination characteristics
of Phillyrea angustifolia L. and P. latifolia L. (Oleaceae), two Mediterranean shrub
species having lignifi ed endocarp. Ann. For. Res. 58(1): 27-37.
Abstract. The aim of this study was to determine the germination charac-
teristics of Phillyrea angustifolia L. and P. latifolia L. seeds in order to
develop an optimized propagation protocol for Phillyrea species. Seeds of
P. angustifolia and P. latifolia were collected from wild plants growing in
Cáceres province (CW Spain) and Andalucía (S Spain), respectively. Per-
centage of water uptake for P. latifolia seeds was calculated. Seeds with
and without endocarp were germinated at different constant and alternat-
ing temperatures. Seeds without endocarp were soaked in distilled water
or gibberellic acid, and then set to germinate. Seeds with endocarp of both
species were stratified at 5 ºC for 30 or 90 days and then the endocarp
was completely removed from the seeds before they were sowed. Chemi-
cal scarification with sulfuric acid and mechanical scarification were tested
on P. angustifolia seeds with endocarp. Phillyrea endocarp was permeable
to water, since Phillyrea seeds with endocarp imbibed water, but water
uptake was faster when the endocarp was removed. Moreover, the enco-
darp could interfere mechanically in the emergence of the radicle, since
seed germination of Phillyrea species was promoted by the complete re-
moval of the lignified endocarp surrounding each seed. Optimal germina-
tion temperature for both species was 15 ºC, and lower temperatures pro-
duced secondary dormancy. Soaking in distilled water or gibberellic acid
did not significantly enhance seed germination. Cold stratification and
chemical scarification treatments were detrimental for seed germination.
Keywords cold stratification, Phillyrea species, treatments before sowing,
seed germination, seed scarification, lignified endocarp.
Authors. Sara Mira ([email protected]), Félix Pérez-García - Department of
Plant Biology, School of Agronomics Engineering, Technical University of Ma-
drid, Madrid, Spain; Luciana Veiga-Barbosa - Department of General Biology,
Federal University of Bahia, Salvador, Bahia, Brazil.
Manuscript received September 29, 2014; revised January 26, 2015; accepted Ja-
nuary 30, 2015; online fi rst February 05, 2015.
27
Ann. For. Res. 58(1): 27-37, 2015 Research article
Introduction bibition and thus seed germination (Baskin &
Baskin 1998, Baskin et al. 2002). Due to the
Seed germination is the most sensitive stage presence of a lignifi ed endocarp, it has been
in the plant ability for spatial colonization suggested that Phillyrea species may presents
(Baskin & Baskin 1998). In Mediterranean physical dormancy (García-Fayos et al. 2001,
ecosystems, evergreens repeatedly face im- Takos & Efthimiou 2003), however, water ab-
portant environmental constraints and cope sorption of the endocarp and dormancy break
with extreme summer droughts, extensive fi res protocols have not been established. Within
and soil erosion (Demmig-Adams & Adams the Oleaceae family, the genus Olea is char-
1996, Chaves et al. 2002, Dimitrakopoulos acterized by physiological dormancy and a
et al. 2013). Climate change models project a woody endocarp that prevents the expansion
reduction in total precipitation and drier sum- of the embryo (Morales-Sillero et al. 2012),
mers (Christensen et al. 2007) and associated and even after total removal of the endocarp,
increase in fi re hazard in Mediterranean re- seed germination is slow and erratic (Mitrakos
gions (Piñol et al. 1998, Pausas et al. 2008). & Diamantoglou 1984). Seed germination of
Therefore, in the Mediterranean areas, plant Phillyrea species was showed to be poor and
regeneration strategies and environmental fac- unreliable in nurseries (Catalán 1991). This er-
tors are closely interlinked, and knowledge on ratic germination of Phillyrea could have an
seed germination of Mediterranean species effect on the presence of plants at different
would be fundamental for the ecosystem con- physiological phases, complicating their man-
servation and for directing regeneration efforts agement and commercialization.
(Varela 2000, Pardos et al. 2005). The general aim of this work was to in-
Phillyrea L. is a genus of 2 species in the Ole- vestigate the seed germination behavior of
aceae family: P. angustifolia L. and P. latifolia Phillyrea species in order to develop an opti-
L. (Andrés 2011). They are evergreen shrubs mized propagation protocol. The specifi c ob-
very representative of the Mediterranean for- jectives of the present study were to determine
est and with high importance in the ecological (i) the optimal temperature requirement for
dynamics (Kutbay & Kilinç, 1994, Herrera et germination of P. angustifolia and P. latifolia
al. 1994). Many of the natural and semi-natu- seeds, (ii) the effect of treatments before sow-
ral forests containing P. angustifolia are under ing on germination for both species, (iii) the
decline due to the impact of anthropogenic water uptake capacity of P. latifolia seeds with
disturbance, and restoration efforts to address and without endocarp and (iv) the effect of dif-
this are underway in many countries. Phillyrea ferent scarifi cation treatments on germination
species are thermophilic and with low water- of P. angustifolia seeds.
ing requirements, and have been recently con-
sidered suitable for landscaping purposes for
their little maintenance needs (De Marco et Materials and methods
al. 2005). Phillyrea species are, therefore, of
growing economical importance. The species Plant material
can be propagated by seed germination and
vegetatively (Piotto & Di Noi 2003), but plant Ripe fruits of P. angustifolia and P. latifolia
rooting is diffi cult (Catalán 1991). Phillyrea were collected in 2011 from wild plants grow-
species produce fl eshy-fruits (drupes), usually ing in Cáceres province (CW Spain) and Anda-
containing a single seed enclosed by a lignifi ed lucía (S Spain), respectively. To carry out the
endocarp. Typically, a lignifi ed endocarp may trials in which seeds without endocarp were
be water-impermeable, thereby preventing im- used, the endocarp of the fruit was completely
28
Mira et al. Seed germination characteristics of ...
removed using pliers and a scalpel. Seeds were P. latifolia assays were also performed with
manually cleaned, kept in paper bags, and then seeds having intact endocarp. P. angustifolia
stored dry under laboratory conditions (at ~23 seeds with endocarp where not included on the
ºC under darkness, 35% relative humidity) assay due to the scarcity of seed material. In
until the start of trials. Visible damaged seeds all trials, seeds that had not germinated at the
were excluded from experiments. end of the incubation period were opened to
determine whether the seed was empty. If so,
Effect of temperature regimes on seed ger- they were excluded from calculation of fi nal
mination germination percentages (Baskin & Baskin
1998). The number of empty seeds was always
Seeds without endocarp of P. angustifolia and equal or less than 5% of the total seeds.
P. latifolia were tested for germination at dif-
ferent constant temperatures (5 ºC, 10 ºC, 15 Effect of treatments before sowing on seed
ºC, 20 ºC, 25 ºC), with a 16-h light photope- germination
riod (provided by cool white fl uorescent tubes
with an irradiance of 35 μmol m2 s-1), and the 3 treatments before sowing were applied by
alternate temperature regimes of 20/7 ºC and using seeds of P. angustifolia and P. latifolia. 4
25/15 ºC (the highest temperature for 16 h in replicates of 25 seeds each were tested for each
light and the lowest one for 8 h in dark). In treatment: (i) soaking in distilled water. Seeds
each trial, four replicates of 25 seeds each for without endocarp were soaked in distilled wa-
P. angustifolia and two replicates of 30 seeds ter at room temperature (~ 23 ºC) for 24 or 72
each for P. latifolia were tested for germination h, (ii) soaking in gibberellic acid (GA ). Seeds
3
on top of two sheets of fi lter paper (previously without endocarp were soaked in a GA solu-
3
moistened with 3.5 mL of distilled water) in tion (1000 mg L-1) at room temperature (~ 23
7-cm-diameter glass Petri dishes. Filter papers ºC) for 24 h, (iii) cold stratifi cation. Seeds with
were rewetted regularly with distilled water, as endocarp were stored in moist vermiculite un-
required. Dishes were checked three times a der darkness at 5 ºC for 30 and 90 days. After
week and germinated seeds were counted and the cold stratifi cation period, the endocarp was
removed. Seeds were considered germinated completely removed from the seeds before
on emergence of the radicle from the seed they were sowed.
coat. The initial incubation period was 35 days After these three treatments, seeds were
for P. angustifolia and 55 days for P. latifolia, tested to germinate at 15 ºC under a 16-h light
which showed a slower germination. To study photoperiod for 65 days. Untreated seeds with-
the effect of high and low temperatures of in- out endocarp were sown in the same conditions
cubation on seed germination at the optimum and they were used as control.
conditions, after incubation at different tem-
peratures, non-germinated seeds were trans- Water uptake during seed soaking
ferred to 15 ºC (which was the temperature that
induced the highest germination percentages). To determine water uptake capacity during
Thus, non-germinated seeds of P. angustifolia seed soaking, 2 replicates of 25 P. latifolia
after 35 days at 5 ºC, 25 ºC and 25/15 ºC were seeds (with and without endocarp) each were
transferred to 15 ºC and then incubated for weighted and then placed in Petri dishes on fi l-
another 35-day period. Non-germinated seeds ter paper moistened with distilled water. After
of P. latifolia after 55 days at 10 ºC, 20 ºC, 1, 2, 24, 48 and 72 h of imbibition, seeds were
25 ºC and 25/15 ºC were transferred to 15 ºC quickly surface-dried with fi lter paper and then
and then incubated for another 137-day period. reweighted. Percentage of water uptake (mean
29
Ann. For. Res. 58(1): 27-37, 2015 Research article
± standard error) was calculated as the amount way factorial ANOVA was used to test the ef-
of water adsorbed by seeds relative to the ini- fects of the different temperature regimes and
tial seed weight. Due to the scarcity of seed treatments before sowing on seed germination
material this assay could not be done with P. capacity. In the same way, to determine differ-
angustifolia seeds. ences among scarifi cation treatments, data were
analysed by means of one-way ANOVA. Where
Effect of scarification treatments on seed ANOVA indicated a signifi cant effect, a com-
germination parison of mean values was carried out through
the least signifi cant difference test (LSD). The
4 scarifi cation treatments were compared on P. statistical analysis of MGT values was also car-
angustifolia seeds with endocarp before they ried out using one-way factorial ANOVA.
were sowed at 15 ºC under a 16-h light pho-
toperiod for 75 days. 4 replicates of 25 seeds
each were tested for each scarifi cation treat- Results
ment: (i) endocarp totally removed. Endocarp
was carefully removed using pliers and a scal- Effect of temperature regimes
pel, (ii) endocarp partially scarifi ed. Endocarp
was cracked with pliers but it was not com- For each species, signifi cant differences (P <
pletely removed from seed, (iii) sulfuric acid 0.001) on the fi nal germination percentages
(6 h) + hot water (80 ºC). Seeds with endocarp were noticed between the temperatures ap-
were immersed in concentrated sulfuric acid plied during the experiments (Table 1). The
for 6 h, then soaked in hot water (80 ºC) for germination percentages reached by P. angus-
18 h, and then repeatedly washed with distilled tifolia seeds without endocarp after 35 days of
water before sowing, (iv) sulfuric acid 30 min. incubation were equal to or less than 2% at the
Seeds with endocarp were immersed in con- lower and higher temperatures (5 ºC, 10 ºC and
centrated sulfuric acid for 30 min and then 25 ºC), the temperatures with the best results
repeatedly washed with distilled water before being 15 ºC and 20 ºC (77% and 70%, respec-
sowing. tively) (Table 1, Figure 1). The fi nal germina-
Due to the scarcity of seed material this as- tion percentages reached by P. latifolia seeds
say could not be done with P. latifolia seeds. without endocarp were equal to or less than
5% for all temperatures assayed except for 15
Statistical analysis ºC (52%) (Table 1, Figure 1). Regarding the
speed of germination (MGT), for P. angustifo-
For all experiments, fi nal germination percent- lia seeds, germination velocity was not signifi -
age (mean value ± standard error) and mean cantly (P > 0.05) affected by the temperature
germination time (MGT, mean value in days regimes (Table 1, Figure 1). Thus, MGT val-
± standard error) were calculated. The latter ues were similar among temperatures, ranging
was determined according to the following from 18 to 24 days. Moreover, P. angustifolia
formula: MGT = ΣDN / ΣN; where D is the seeds showed at 15 ºC a faster germination
number of days counted from the date of sow- (lower MGT values) than P. latifolia seeds (20
ing and N is the number of seeds germinated and 29 days, respectively).
on day D (Ellis & Roberts, 1981). The values P. angustifolia seeds that did not germinate
of fi nal germination percentages were arcsine after being incubated at the temperature re-
square-root transformed and then subjected to gimes of 5 ºC, 25 ºC or 25/15 ºC for 35 days,
analysis of variance (ANOVA) using SPSS were transferred to 15 ºC. Germination per-
(untransformed data appear in Tables). One- centage was increased in all cases, with fi nal
30
Mira et al. Seed germination characteristics of ...
Table 1 Final germination percentage and mean germination time (MGT) for Phillyrea angustifolia and
P. latifolia seeds without endocarp incubated at different temperature regimes for 35 days. Means
within a column followed by the same letter are not signifi cantly different according to the LSD
test at P > 0.05
Phillyrea angustifolia Phillyrea latifolia
Temperature
Germination MGT Germination MGT
(ºC)
(% ± SE) (days ± SE) (% ± SE) (days ± SE)
5 0a - NO NO
10 0a - 5 ± 3.53a NC
15 77 ± 5.72d 20.35 ± 1.20a 52 ± 1.06b 29.00 ± 0.13
20 70 ± 5.92d 23.12 ± 0.44a 2 ± 1.41a NC
25 2 ± 1.73ab NC 0 -
20/7 10 ± 1.73b 26.50 ± 4.07a NO NO
25/15 39 ± 3.57c 18.22 ± 0.57a 0 -
Note. NC: MGT value was not calculated when the fi nal germination percentage was equal to or less than 5%. NO: trial
not carried out due to the scarcity of seed material.
100
P. angustifolia P. latifolia
80
%)
n ( 60
o
ati
n
mi 40
er
G
20
0
0 10 20 30 0 10 20 30
Time (days)
Figure 1 Germination time courses of Phillyrea angustifolia and P. latifolia seeds without endocarp incu-
bated for 35 days at different temperature regimes: 5 ºC (●), 10 ºC (○), 15 ºC (▼), 20 ºC (□), 25
ºC ((cid:161)), 20/7 ºC ((cid:85)) and 25/15 ºC (■).
values being registered from 30% to 83% (Fi- were transferred to 15 ºC their germination in-
gure 2). creased greatly, with fi nal values from 70% to
Final germination percentages reached by 85%. P. latifolia seeds without endocarp that
P. latifolia seeds with and without endocarp at were moved to 15 ºC after a 55-day period of
different temperatures are showed in Figure 3. incubation at 10 ºC, 20 ºC, 25 ºC and 25/15 ºC
For P. latifolia seeds with endocarp, germina- increased their germination percentage from
tion occurred only at 15 ºC. However, when 60% to 87% after another 137-day period.
those seeds with endocarp incubated at 10 ºC,
20 ºC, 25 ºC and 25/15ºC for a 55-day period
31
Ann. For. Res. 58(1): 27-37, 2015 Research article
100
80
%)
n ( 60
o
ati
n
mi
er 40
G
20
0
5”C 15”C 10”C 15”C 20”C 25”C 15”C 20/7”C 25/15”C 15”C
Temperature of germination (”C)
Figure 2 Final germination percentages of Phillyrea angustifolia seeds without endocarp incubated at dif-
ferent temperature regimes. Seeds were incubated for 35 days and then those at 5 ºC, 25 ºCand
25/15 ºC were transferred to 15 ºC for another 35-day period. Filled bars represent fi nal germina-
tion (± standard error) at the indicated temperature after 35 days and striped bars after another
35-day period.
100
endocarp No endocarp
5”C 15”C 10”C 15”C
80
%)
n ( 60
o
ati
n
mi 40
er
G
20
0
10 15 15 20 15 25 15 25/15 15 10 15 15 20 15 25 15 25/15 15
Temperature of germination (”C)
Figure 3 Final germination percentage of Phillyrea latifolia seeds with and without endocarp incubated at
different temperatures for 55 days and then transferred to 15 ºC for another 137-day period. Filled
bars represent fi nal germination (± standard error) at the indicated temperature after 55 days and
striped bars after another 137-day period.
Treatments before sowing trol seeds (untreated seeds) and seeds soaked
in distilled water or GA . However, stratifi ca-
3
The effect of different treatments before sow- tion of P. angustifolia seeds at 5 ºC for 90 days
ing on germination of P. angustifolia and P. signifi cantly (P < 0.001) decreased the fi nal
latifolia seeds is shown in Table 2 and Figu- germination percentage when compared to the
re 4. For P. angustifolia seeds, no signifi cant control (9% vs. 81%, respectively). Germi-
differences (P > 0.05) were found among the nation speed was not signifi cantly (P > 0.05)
fi nal germination percentages reached by con- increased by the different treatments before
32
Mira et al. Seed germination characteristics of ...
sowing assayed. For P. angustifolia seeds, all (P < 0.001) lower than that of seeds without
treatments signifi cantly (P < 0.001) reduced endocarp (81%) (Table 3). Germination speed
the fi nal germination percentages. Germination was signifi cantly (P < 0.001) higher for seeds
speed was higher for P. latifolia seeds soaked scarifi ed with sulphuric acid for 6 h than that
for 24 h and 72 h in distilled water than that of of control seeds (3.4 days vs. 20.8 days, re-
control seeds, but these differences were not spectively).
signifi cant (P > 0.05).
Water uptake Discussion
P. latifolia seeds without endocarp absorbed Regeneration potential of Phillyrea species
water quickly after 24 h immersion in dis- depends on the effect of ambient conditions
tilled water (Figure 5), being registered seed on its propagation process, and knowledge of
mass increasing with 60% of the initial value. the germination requirements would be funda-
P. latifolia seeds with endocarp also absorbed mental for the conservation of this species. Our
water but at a lower rate. Thus, mean increase results indicate that Phillyrea species germina-
in mass for seeds without endocarp after 24 h tion is slow. The highest germination percent-
was more than twice of that in seeds with en- age after a 35-day period was obtained at 15 ºC
docarp (26%). After 48 h, seed mass increase for both species, being maximum germination
was 67% in seed without endocarp, and 39% 77% for P. angustifolia and 52% for P. latifolia.
in seeds with endocarp. After 72 h of immer- Also, temperature regime for P. latifolia was
sion in distilled water, seed mass increase was very restrictive, since seeds did not germinate
68% in seed without endocarp, and 47% in at either 25 ºC or 25/15 ºC. These results are
seed with endocarp. in agreement with optimal germination tem-
perature for most Mediterranean shrub species
Scarifi cation treatments ranging between 15 ºC and 20 ºC (Thanos et al.
1992, 1995). Alternating temperatures (20/7
P. angustifolia seeds whose endocarp was ºC and 25/15 ºC) resulted in low germination
cracked but not totally removed and seeds sub- percentages, although previous works stated
merged in concentrated sulfuric acid showed that Phillyrea seeds germinated a 90% after 60
a similar germination (22-26%), signifi cantly days at 20/7 ºC (Herranz et al. 2006), or a 90%
Table 2 Final germination percentage and mean germination time (MGT) of Phillyrea angustifolia and P.
latifolia seeds without endocarp after several treatments before sowing. Seeds were germinated at
15 ºC for 65 days. Untreated seeds without endocarp were used as control. Means within a column
followed by the same letter are not signifi cantly different according to the LSD test at P > 0.05.
Phillyrea angustifolia Phillyrea latifolia
Treatment before sowing Germination MGT Germination MGT
(% ± SE) (days ± SE) (% ± SE) (days ± SE)
Control 81 ± 5.36b 20.85 ± 0.86a 62 ± 5.20b 32.57 ± 2.19a
Soaking in distilled water for 24 h 84 ± 5.48b 16.20 ± 0.74a 14 ± 1.73a 31.12 ± 1.64a
72 h 86 ± 4.58b 12.67 ± 0.19a 10 ± 1.95a 29.00 ± 2.50a
Soaking in GA 79 ± 3.84b 16.17 ± 0.48a 21 ± 6.98a 39.62 ± 0.92ab
3
Stratifi cation at 5 ºC 30 days NO NO 12 ± 0.65a 56.50 ± 0.56c
90 days 9 ± 2.17a 19.12 ± 6.32a 17 ± 2.98a 52.25 ± 4.42bc
Note. NO: trial not carried out due to the scarcity of seed material.
33
Ann. For. Res. 58(1): 27-37, 2015 Research article
100
P. angustifolia P. latifolia
80
%)
n ( 60
o
ati
n
mi 40
er
G
20
0
0 20 40 60 0 20 40 60
Time (days)
Figure 4 Germination time courses of Phillyrea angustifolia and P. latifolia seeds without endocarp after
different treatments before sowing: control (□), soaking in distilled water for 24 h (●), soaking in
distilled water for 72 h (○), soaking in a GA solution (1000 mg L-1) for 24 h (▼), cold stratifi ca-
3
tion at 5 ºC for 30 days ((cid:85)) and 90 days (■). Seeds were incubated at 15 ºC for 65 days
80
seeds without endocarp
seeds with endocarp
W) 60
D
%
n (
o
pti 40
or
s
b
a
er
at
W 20
0
1h 2h 24h 48h 72h
Time of imbibition
Figure 5 Mean (± standard error) increase in mass of Phillyrea latifolia seeds with and without endocarp
placed on fi lter paper moistened with distilled water at ~23 ºC.
after 15 days at 20/10 ºC (García-Fayos et al. Baskin & Baskin 1998, Martínez-García et al.
2001). This could indicate a variation of the 2012), concerning the seed dormancy (Pérez-
optimal germination temperatures for differ- García et al. 2012), or seed longevity (Lazar
ent populations of the same species. One of the et al. 2014, Mira et al. 2011a, 2011b, 2014).
most important survival adaptations for plant However, in some forest species, as Populus
species growing under variable and unpredict- euphratica and Pinus nigra, it has been shown
able environmental conditions, as in the Medi- that source origin had minimal infl uence on
terranean forests, is the intraspecifi c variation seed germination or seedling quality (Ivetic &
of germination requirements (Kigel 1995, Skoric 2013, Soleimani et al. 2014).
34
Mira et al. Seed germination characteristics of ...
It is known that some seeds with ligni- variability on the endocarp permeability and
fi ed endocarp germinate well following cold hardness in Phillyrea species, as has been pre-
stratifi cation (Baskin et al. 2002), however, viously suggested (Traveset et al. 2007, Arnal
cold stratifi cation of Phillyrea seeds was det- 2013). In our study, P. latifolia seeds with endo-
rimental for seed germination. Incubation at carp absorbed water during soaking, although
low temperatures (5 ºC for P. angustifolia and more slowly than in seeds without endocarp.
10 ºC for P. latifolia) seemed to induce a sec- This results would indicate that P. latifolia
ondary dormancy, since fi nal germination did seeds do not exhibit physical dormancy, ac-
not achieve maximum values when seeds were cording to the classifi cation system of Baskin
transferred to 15 ºC. The ineffi ciency of a cold & Baskin (2004), were physical dormancy is
stratifi cation treatment agrees with previous defi ned as the result of a water-impermeable
work in Phillyrea species (García-Fayos et al. layer in the seed or fruit. Similar results had
2001), but it is a especially interesting result been reported in several species with lignifi ed
since cold stratifi cation is a common treatment endocarp (Baskin et al. 2002) and some spe-
for forestry species and some seed producing cies within the Oleaceae family, like Olea sp.
companies recommend it for these particular (Cuneo et al. 2010).
species. On the other side, seed incubation at Total removal of the endocarp with pliers was
high temperatures, 25 ºC and 25/15 ºC, result- the technique that showed best results regard-
ed in a low germination percentage for both ing germination of P. angustifolia, while this
species but did not induce dormancy. morpho-physiological process was not pro-
Treatments before sowing through soaking moted when endocarp was cracked. Moreover,
in distilled water or in a gibberellic acid solu- P. latifolia seeds with endocarp incubated at 10
tion did not signifi cantly increase fi nal germi- ºC, 20 ºC, 25 ºC or 25/15 ºC did not germinate
nation for P. angustifolia seeds, and they were for 55 days, but achieved high germination
clearly detrimental for P. latifolia. Moreover, percentages when transferred at 15 ºC. Other
acid scarifi cation with sulfuric acid registered authors found that seeds of P. latifolia collected
very poor results in P. angustifolia, which is from the soil in previous years showed a high
especially meaningful since this technique has germination (Yucedag & Gultekin 2011), and
been suggested as one of the best to promote that Olea europaea seed germination in the soil
germination in several species with lignifi ed did not occur until complete decomposition of
endocarp (Bonner & Karrfalt 2008), and it has the endocarp (Cuneo et al. 2010). Our results
been previously recommended for Phillyrea suggest that Phillyrea species may present a
species by seed producing companies and pre- lignifi ed endocarp that interferes mechanically
vious reports (Piotto & Di Noi 2003, Bacchetta in the emergence of the radicle but not in the
et al. 2008). These contradictory results could absorption of water, and that complete remov-
be explained by an inter- and intra-population al of endocarp is necessary to achieve the full
Table 3 Final germination percentage and mean germination time (MGT) for Phillyrea angustifolia seeds
after several scarifi cation treatments. Seeds were incubated at 15 ºC for 75 days. Means within a
column followed by the same letter are not signifi cantly different according to the LSD test at P
> 0.05.
Scarifi cation treatment Germination (% ± SE) MGT (days ± SE)
Endocarp removed with pliers 81 ± 5.36b 20.85 ± 0.86b
Endocarp cracked 22 ± 2.24a 48.42 ± 3.32d
SO H (6 h)+ hot water (80 ºC) 22 ± 4.58a 3.37 ± 0.27a
4 2
SO H (30 min) 26 ± 8.18a 34.75 ± 1.08c
4 2
35
Ann. For. Res. 58(1): 27-37, 2015 Research article
germination. In nature, Phillyrea fruits spread de Plantas Silvestres]. Asturias, Spain: Principado de
in winter, their seeds remaining in the soil and Asturias/La Caixa. 378 pp. Anexo Digital I. pp. 15.
Baskin C.C., Baskin J.M., 1998. Seeds: Ecology, bioge-
with time the endocarp might degenerate al-
ography, and evolution of dormancy and germination.
lowing seeds to germinate during the period of
London, UK: Academic Press, pp. 37-39.
early spring temperatures and rains. Baskin J.M., Baskin C.C., 2004. A classifi cation system for
seed dormancy. Seed Science Research 14: 1-16. DOI:
10.1079/ SSR2003150.
Baskin C.C., Zackrisson O., Baskin J.M., 2002. Role of
Conclusions
warm stratifi cation in promoting germination of seeds
of Empetrum hermaphroditum (Empetraceae), a circum-
Our data provided useful information in ger- boreal species with a stony endocarp. American Journal
of Botany 89: 486-493. DOI: 10.3732/ ajb.89.3.486.
mination protocols for Phillyrea species prop-
Bonner F.T., Karrfalt R., 2008. The woody plant seed man-
agation. Optimal germination temperature for
ual. Agric. Handbook No. 727. Washington, DC. U.S.
Phillyrea species was 15 ºC, lower tempera- Department of Agriculture, Forest Service. pp. 107.
tures resulting in secondary dormancy. Treat- Catalán G., 1991. Phillyrea. In: Forest Tree and Shrub
Seeds [Semillas de Árboles y Arbustos Forestales] Cata-
ments of cold stratifi cation, soaking in distilled
lán G., (ed.) Madrid, Spain: Instituto Nacional para la
water or gibberellic acid did not improve seed
Conservación de la Naturaleza, pp. 265-266.
germination. Our results proved that P. latifo- Chaves M.M., Pereira J.S., Maroco J., Rodrigues M.L.,
lia endocarp was permeable to water but could Ricardo C.P.P., Osorio M.L., Carvalho I., Faria T., Pi-
nheiro C., 2002. How plants cope with water stress in
mechanically interfere with the radicle emer-
the fi eld?. Photosynthesis and growth. Annals of Botany
gence, and total removal of the endocarp was
89: 907–916. DOI: 10.1093/aob/mcf105.
the technique that showed best results for seed Christensen J.H., Hewitson B., Busuioc A., Chen A., Gao
germination improving. X., Held I., Jones R., Kolli R.K., Kwon W.T., Laprise
R., et al. 2007. Regional climate projections. In: Solo-
mon S., Qin D., Manning M., Chen Z., Marquis M.,
Averyt K.B., Tignor M., Miller H.L., (eds.) Climate
Acknowledgement Change 2007: The physical science basis. Contribution
of working group to the fourth assessment report of the
intergovernmental panel on climate change. Cambridge,
Authors would like to thank Carlos Ruiz for
UK: Cambridge University Press, pp. 847-940.
his help on seed collecting. Semillas Mon-
Cuneo P., Offord C.A., Leishman M.R., 2010. Seed ecol-
taraz Company donated seed material. Luciana ogy of the invasive woody plant African Olive (Olea
Veiga-Barbosa was supported by a grant from europaea subsp. cuspidata): implications for manage-
ment and restoration. Australian Journal of Botany 58:
Fundación Carolina (Spain).
342-348. DOI: 10.1071/BT10061.
Demmig-Adams B., Adams III W.W., 1996. The role of
xanthophyll cycle carotenoids in the protection of pho-
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