Cc. Baskin et al., SEED DORMANCY IN THE COLORADO PLATEAU SHRUB MAHONIA-FREMONTII (BERBERIDACEAE) AND ITS ECOLOGICAL AND EVOLUTIONARY IMPLICATIONS, The Southwestern naturalist, 38(2), 1993, pp. 91-99
Freshly-matured seeds of Mahonia fremontii collected in southern Utah
in late July 1990 were used to investigate dormancy breaking and germi
nation requirements. Seeds had fully developed spatulate embryos, and
seed coats were permeable to water. Dormancy was broken by 6-10 weeks
of cold stratification at a daily (12/12 h) thermoperiod of 5/1-degree
s-C. Seeds germinated to 100% at 15/6 following 10 weeks at 5/1, and t
hose kept at 5/1-degrees-C germinated to 97% after 14 weeks. Seeds do
not require light for germination. A warm stratification treatment at
30/15-degrees-C for 3 or more days prior to cold stratification at 5/1
-degrees-C significantly increased germination. Seeds ''dispersed'' (i
.e., added to the August to March sequence of simulated habitat temper
atures) in August, September, October, November and December germinate
d to 98-100% in March. Since gibberellic acid and afterripening in dry
storage were somewhat effective in breaking dormancy and excised embr
yos of 10-month-old seeds grew normally, seeds have inter-mediate phys
iological dormancy (PD), a first report in the Berberidaceae. Seeds of
Berberidaceae with PD are more advanced than other members of the fam
ily with morphophysiological dormancy.