| Abstract:
The effects of environmental factors on germination and longevity of downy brome seeds were examined in laboratory and field experiments. Downy brome could germinate in a broad range of temperatures (15/6, 20/10, 25/15, 30/15, and 35/20oC). The germ inability, however, was different depending on the temperature range and the results showed that the highest germination was occurred in 20/10ºC (91%) under continuous dark regime, while the lowest germination percentage was observed in 35/20ºC (5%) under light/dark conditions. Salinity showed significant adverse effect on germination of this weed, so that the highest germ inability was at 0 concentration of NaCl (89%).
Increased salinity levels significantly decreased downy brome germination and its germination completely ceased at 320 mM NaCl. This study indicated that increasing pH in the range of 4 to 8 resulted in enhanced germination percentage, while further increase of pH significantly reduced germ inability.
Another experiment in which seeds were after-ripened at different depths in the field showed that increased burial depths from 0 to 10 cm accelerated seed after ripening and the lowest germination occurred in the seeds which were placed on the soil surface.
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