Baskin, Carol C. , Baskin, Jerry M. , Yoshinaga, Alvin .
Germintion of druplets in multi-seeded drupes of the Hawaiian montane/subalpine shrub, Styphelia tameiameiae, a case for deep physiological dormancy broken by high temperatures.
This study addressed the difficulty of germinating druplets (hereafter seeds) in the multi-seeded stony dispersal units (drupes) of Styphelia tameiameiae (Ericaceae). Embryos in fresh seeds were 77% the length of the endosperm, and seeds inside the intact drupes imbibed water. Thus, seeds have physiological dormancy (PD). We monitored germination at 15/16, 20/10, and 25/15șC for 162 wk, after which each drupe was cut open and ungerminated seeds counted. Drupes contained 1-6 seeds, and the total number of seeds in all treatments and controls was 1977, with 20, 29, 25, 18, 7 and <1% of them occurring in 1-, 2-, 3-, 4-, 5-, and 6-seeded drupes, respectively. Percentage of seeds germinating in 1-, 2-, 3-, 4-, 5-, and 6-seeded drupes was 74, 66, 65, 72, 56, and 0, respectively. Neither warm nor cold stratification for 6 or 12 wk significantly increased germination, compared to controls incubated at 25/15șC for 162 wk, where 72% of the seeds in the drupes germinated. At 25/15șC, 24-49 wk were required for 20% of the seeds to germinate. Warm followed by cold stratification did not promote germination, and there was no widening of the temperature range for germination. Like seeds of other species known to have deep PD, those of S. tameiameiae required extended periods of time (16 to ≥162 wk) to come out of dormancy and germinate, gibberellic acid (GA3) did not promote germination, and excised embryos failed to grow. Thus, we conclude that seeds of S. tameiameiae have deep PD. However, unlike seeds of other species with deep PD, those of S. tameiameiae required an extensive period of warm rather than cold stratification to come out of dormancy. This is the first report of deep PD being broken by warm stratification.
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1 - University of Kentucky, Department of Biological Sciences, 101 Morgan Bld, Lexington, Kentucky, 40506-0225, USA
2 - University of Hawaii, Center for Conservation Research and Training, Honolulu, Hawaii, 96822, USA
Presentation Type: Oral Paper
Location: Salon F - Austin Grand Ballroom/Hilton
Date: Wednesday, August 17th, 2005
Time: 9:00 AM