Germination rates and timing of Juglans californica at differing cold stratification temperatures
Start Date
14-12-2022 11:40 AM
End Date
14-12-2022 11:45 AM
Description
Juglans californica, the foundational species of walnut woodland communities in Southern California, is under threat from climate change. A temperature-dependent cold stratification period regulates seed germination of J. californica, and rising temperatures may affect seed dormancy. Literature based on limited data from the middle of the last century suggests that the optimal seed germination temperature of J. californica is 5°C. To find the optimal temperature, J. californica is incubated in a broad range of temperatures. Initially, field-collected seeds were dehusked, imbibed for 24 hours, incubated at fixed temperatures (5°C, 10°C, 15°C) for 120 days, and checked weekly for germination– the emergence of the cotyledon. After 15 weeks, un-germinated seeds were further incubated at ambient air temperature for 30 days. In 2020, treatment was repeated at 5°C, 10°C, 15°C, and 20°C. The germination rate was highest at a stratification temperature of 10°C. Increases in temperature will affect J. californica's ability to germinate and the length of the cold stratification period will affect its ability to match environmental conditions, such as seasonal rainfall. Findings may inform conservation efforts for J. californica and other plant species. J. californica seeds will be incubated at 2ºC intervals from 2ºC to 20ºC for further results.
Germination rates and timing of Juglans californica at differing cold stratification temperatures
Juglans californica, the foundational species of walnut woodland communities in Southern California, is under threat from climate change. A temperature-dependent cold stratification period regulates seed germination of J. californica, and rising temperatures may affect seed dormancy. Literature based on limited data from the middle of the last century suggests that the optimal seed germination temperature of J. californica is 5°C. To find the optimal temperature, J. californica is incubated in a broad range of temperatures. Initially, field-collected seeds were dehusked, imbibed for 24 hours, incubated at fixed temperatures (5°C, 10°C, 15°C) for 120 days, and checked weekly for germination– the emergence of the cotyledon. After 15 weeks, un-germinated seeds were further incubated at ambient air temperature for 30 days. In 2020, treatment was repeated at 5°C, 10°C, 15°C, and 20°C. The germination rate was highest at a stratification temperature of 10°C. Increases in temperature will affect J. californica's ability to germinate and the length of the cold stratification period will affect its ability to match environmental conditions, such as seasonal rainfall. Findings may inform conservation efforts for J. californica and other plant species. J. californica seeds will be incubated at 2ºC intervals from 2ºC to 20ºC for further results.
