The Fagaceae comprise over 600 species of trees and shrubs within six genera which provide timber. The fruits are one-seeded nuts which may be enclosed in a cupule or a bur. Quercus and Castanea spp. show recalcitrant seed storage behaviour, whereas Fagus and Nothofagus spp. show orthodox seed storage behaviour (although careful handling, drying, and long germination test periods may be required to demonstrate this in some Fagus spp.).
SEED DORMANCY AND GERMINATION
Dormancy can be a severe problem in some species (e.g. Fagus spp.) requiring long pre-chill treatments and overall germination test periods of more than 6 months. No detailed information is provided here for any one genus, but Table 38.1 provides a summary of recommended germination test procedures and dormancy-breaking treatments, and the algorithm below may be helpful in developing suitable germination test regimes for other species.
RBG Kew Wakehurst Place algorithm
The first step in the algorithm is to test the seeds at a constant temperature of 21°C with light applied for 12h/d.
If this is not successful in promoting full germination then the second step of the algorithm is to pre-chill a further sample of seeds at 2° to 6°C for 8w and then test at a constant temperature of 21°C with light applied for 12h/d.
In some species it is known that an 8w pre-chill treatment will be an inadequate dormancy-breaking treatment (e.g. see Table 38.1). Consequently where the seeds are known to be dormant and the algorithm does not promote full germination gene banks should consider extending the pre-chill treatment.
TABLE 38.1 Summary of germination test recommendations for species within the Fagaceae
|
Species and Authority |
Substrate |
Temperature |
Duration |
Additional directions |
Source |
|
Castanea sativa Mill.
|
TS; S |
20°/30°C |
21d |
pre-soak, 48h, cut off 1/3 of seed at scar end and remove testa |
ISTA |
|
|
|
|
if dry, pre-soak, 48h, cold water |
G&R |
|
|
Castanea spp. |
|
|
28d |
pre-chill, 1°-5°C, 30-60d |
Riley |
|
Fagus sylvatica L.
|
TP |
3°-5°C |
|
test for up to 24w |
ISTA |
|
|
|
|
pre-chill, 1°-5°C, 4-20w |
G&R |
|
|
Nothofagus obliqua (Mirbel) Oersted |
TP |
20°/30°C |
28d |
two tests: with and without pre-chill, 3°-5°C, 28d |
ISTA |
|
Nothofagus procera (Poeppig & Endl.) Oersted |
TP |
20°/30°C |
28d |
|
ISTA |
|
Nothofagus spp. |
|
|
|
pre-chill, 1°-5°C, 0-9w, GA |
G&R |
|
Quercus alba L. |
TP |
20°/30°C |
28d |
|
AOSA |
|
Quercus muehlenbergii Engelm. |
TP |
20°/30°C |
28d |
|
AOSA |
|
Quercus virginiana Mill. |
TP |
20°/30°C |
28d |
|
AOSA |
|
Quercus spp. |
TS; S |
20°C |
28d |
pre-soak, 48h, cut off 1/3 of seed at scar end and remove testa |
ISTA |
|
Quercus spp. (red and black oaks) |
TP |
20°/30°C |
14d |
cut 1/3 off cup at scar end, then remove pericarp |
AOSA |
