Seed germination patterns of Salvia mellifera in fire-prone environments

Summary

Salvia mellifera seeds from coastal sage, chaparal and desert scrub in southern California failed to germinate in the dark unless exposed to powdered charred wood. This pattern was observed for seeds given a one month stratification at 5 C and for ones not stratified and also for seeds incubated under continuous 23 C or a diurnal alternation of 13 C/23 C. Dark inhibition of germination was also overcome, but only in seeds from chaparral populations, if seeds were incubated on commerical potting soil under alternating 13 C/23 C. Seeds in the light germinated readily in all but one population from desert scrub vegetation. Germination of seeds from this population was markedly stimulated by dry heating of the seeds at either 70 C for 5 h or 115 C for 5 min. For all populations there were numerous significant interactions between incubation temperature, pre-chilling stratification, light, and heating/charred wood treatments. Timing of germination was remarkably consistent between populations; the vast majority of seeds germinated within the first week at 23 C (or 13 C/23 C) regardless of whether or not they had received a pre-chilling treatment.