Influence of Soil Moisture, Temperature, and Compaction on the Germination and Emergence of Downy Brome (Bromus tectorum)

Abstract
The influence of soil moisture stress, temperature, and bulk density on the germination and seedling emergence of downy brome (Bromus tectorum L.) was investigated in the laboratory. Reductions in soil matric potential from -2 to -16 bars markedly reduced the percentage and rate of emergence. Seedling emergence was better at constant than at alternating temperatures. At high matric potentials, the rate of emergence was accelerated by warmer soil temperature (20 C), while at very low matric potentials, the percentage and rate of seedling emergence were least restricted at cooler temperatures (10 and 15 C). Soil matric potential did not influence the percentage or rate of emergence of seedlings grown from seed lots harvested during climatologically diverse years. Seedling emergence but not germination was inhibited by increased levels of soil compaction. Soil compaction times moisture interaction were not observed, as measured by final seedling emergence.