Patterns of change in seed dormancy and persistence of Bromus diandrus Roth. (great brome) in the field
1986
Cheam, A.H. (Western Australian Dept. of Agriculture, Perth. Weed Agronomy Branch)
Mature seeds from Western Australia were dormant when freshly harvested. This dormancy was lost progressively over summer. The rate of loss of dormancy was more rapid in the northern than in the southern accessions. Compared with bare soil, a wheat stubble microenvironment favoured the relief of dormancy during the initial period of dormancy breakdown. Shallow burial of newly shed dormant seeds also accelerated the after-ripening process. Germination of non-dormant seeds during summer was minimised by high temperatures and low soil moisture content. By autumn-winter, almost all the seeds became germinable. At 20-10 deg C, the temperature regime corresponding to late autumn, 95-99 percent germination occurred under constant darkness, but in the light germination varied from 55 to 95 percent. In the field, complete mass germination did not occur but germination was a well-defined event. There was little germination following this pulse until the succeeding autumn-winter.
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