Respiration in dormant and non-dormant bitterbrush seeds

Bitterbrush (Purshia tridentata dc.) seed dormancy is not understood but ma y result from a metabolic block by a chemical inhibitor. To determine wheth er dormancy affects seed respiration, we compared CO2, evolution from indiv idual imbibed dormant and non-dormant seeds and from germinating seeds, usi ng Fourier transform infrared photoacoustic spectroscopy. We found CO2, evo lution did not differ between dormant and non-dormant seeds, and that it ac celerated with germination and growth. Our results are in agreement with ot her studies indicating that dormant seeds respire. We conclude that high re spiration rates in dormant bitterbrush seeds can decrease seedling vigor, a nd we recommend bitterbrush be sown when soil temperatures are cool enough to prevent significant losses of respiratory substrate from imbibed-dormant seeds. (C) 2001 Academic Press.