International Journal of Mediterranean Ecology - Ecologia ...

Results
After 16 days, no difference of germination
were observed between the three studied
species. Moreover, no germination was
recorded until day 4. Among the pre-sowing
seed treatments, the 20-30 min acid treatments
for C. azel and C. arich and boiling
water or the 30 min acid treatment for C.
comosum resulted in the lowest delay of germination
(6 d). Chemical scarification with
sulphuric acid for 30 min improved the final
germination percentages for the three Calligonum
species and was consistently the
most effective pretreatment (Figures 2a, b). A
two-way ANOVA of germination and relative
germination indicated a significant main
effect of species and treatments; however their
interaction did not show any significant effect
(Table 2). Compared with the control, the 20-
30 min acid treatments significantly increased
the final germination percentages for C.
comosum and C. arich and the six pre-sowing
seed treatments significantly increased the
seed germination of C. azel (Figure 2a). More
than 60% relative seed germination was
achieved for all Calligonum species when
seeds were treated for 30 min in sulphuric
acid (Figure 2b). For C. comosum and C. azel,
all pre-sowing seed treatments significantly
increased the relative germination, whereas
immersion in concentrated acid for either 20
or 30 min significantly increased this parameter
for C. arich. The index of germination
velocity, calculated by using a modified Timson’s
index, showed that the highest rate was
obtained when seeds of the three species were
subjected to acid treatment for 30 min (Figure
3). A two-way ANOVA of the germination
rate indicated a significant effect of
species and treatments (Table 2).
For all species, there were significant differences
between the various seed pretreatments
concerning the seed dormancy and relative
dormancy (Table 2). Scarifying seeds of the
three species with sulphuric acid for 30 min
resulted in the lowest percentage of dormancy
and relative dormancy (Figures 4a, b).
Regardless of the pre-sowing seed treatments,
C. comosum had significantly a lower dormancy
and relative dormancy than C. comosum
and C. azel. The various seed treatments
had a significant effect on the seed mortality
(Table 2). Compared with the control and
other treatments, there were fewer dead seeds
when seeds were subjected to acid treatment
ecologia mediterranea – Vol. 38 (1) – 2012
Effects of some seed-coat dormancy breaking treatments on germination
of three Calligonum species occurring in Southern desert of Tunisia
See Figure 2 for legend.
Figure 4 – Changes in the seed dormancy (a) and seed relative dormancy (b)
of three Calligonum species during 30 d after different pre-sowing
seed treatments (Dhief et al.).
See Figure 2 for legend.
Figure 5 – Changes in the seed mortality of three Calligonum species during
30 d after different pre-sowing seed treatments (Dhief et al.).
23