Respiration in dormant and non-dormant bitterbrush seeds

Bitterbrush (Purshia tridentata dc.) seed dormancy is not understood but may result from a metabolic block by a chemical inhibitor. To determine whether dormancy affects seed respiration, we compared CO2evolution from individual imbibed dormant and non-dormant seeds and from germinating seeds, using Fourier transform infrared photoacoustic spectroscopy. We found CO2evolution did not differ between dormant and non-dormant seeds, and that it accelerated with germination and growth. Our results are in agreement with other studies indicating that dormant seeds respire. We conclude that high respiration rates in dormant bitterbrush seeds can decrease seedling vigor, and we recommend bitterbrush be sown when soil temperatures are cool enough to prevent significant losses of respiratory substrate from imbibed dormant seeds.