MUNoz & JIMENEZ Capsule development and germination in Phragmipedium


 100
 OP. humboldtii
 80 O- P. longifolium
 SP. pearcei
' 60 *

4e 40

 20

 0
 Seed viability Germination Dead protocorms

FIGURE 3. Seed viability, germination rate corrected with the
 percentage of seed viability of each capsule and death
 rate of germinated seeds in P humboldtii, P. longifolium
 and P pearcei. Data represent the mean of at least three
 replicates  SD. *Four weeks after sowing. **Eight
 weeks after sowing.

 Viable seeds of P. longifolium and P pearcei started
geminating during the first two weeks of culture.
Afterwards, the germination rate decreased until, atweek
four, no additional germinating seeds were observed. On
the other hand, germination in P humboldtii occurred in
a very low rate, with only a slight increase during the
evaluated period of eight weeks (Fig. 4).
 Culture medium had a significant effect on seed
germination (Table 1), evident in P. longifolium and
P. pearcei only during the first week by a higher
germination rate on half-strength Murashige and
Skoog medium. Thereafter, seed germination in these
two species behaved very similarly (Fig. 4), without
significant differences according to the Post-Hoc


 50
 Knudson C _
 40 --
 30
 P- P. humboldtii
 S20 P. longifolium
 S-*- P. pearcei
 10o
 50 i^ -- -- ...... .... .* ...* *.... ...
 MS 50%
 40

 30

 20
 10

 o
 0 I----* -- 4 ...... .....--t" "T-. .
 0 1 2 3 4 5 6 7 8 9
 Weeks
FIGURE 4. Germination rate in seeds of P. humboldtii, P.
 longifolium and P. pearcei along time on Knudson C and
 half-strength Murashige and Skoog media (MS 50%).

Tukey's Honest-Significant-Difference-Test (HSD)
for unequal N (Spjotvoll/Stoline).
 No effect of the light conditions tested could be
observed on seed germination in any of the evaluated
species (p>0.05) as presented in Table 1. However,
among the protocorms cultured on the Knudson
C medium, a higher growth rate was observed
afterwards in those germinated under dark conditions.
The protocorms germinated in the dark were placed
under a photoperiod of 12 hours of light after six
weeks of culture, and one week later they began to
change their color from white to green. By that time,


Table 1. Multivariate test of significance of seed germination corrected with the viability rate for each capsule of the three
Phragmipedium species studied in response to culture medium and light conditions.

Source of variation Test Value F Effect df Error df p

Intercept Wilks 0.031021 226.4653 4 29 0.000000
Species (A) Wilks 0.038002 29.9406 8 58 0.000000
Culture medium (B) Wilks 0.451880 8.7941 4 29 0.000089
Light conditions (C) Wilks 0.757612 2.3195 4 29 0.080649
AxB Wilks 0.469325 3.3328 8 58 0.003338
AxC Wilks 0.421866 3.9122 8 58 0.000948
BxC Wilks 0.691800 3.2299 4 29 0.026159
AxBxC Wilks 0.454910 3.4992 8 58 0.002320


LANKESTERIANA8(2), August 2008. 0 Universidad de Costa Rica, 2008.