SOIL-TEMPERATURE, SOIL-MOISTURE, AND SEED BURIAL DEPTH EFFECTS ON REDSTEM FILAREE (ERODIUM-CICUTARIUM) EMERGENCE

A study was conducted under controlled environmental conditions to determine the effect of soil temperature, soil moisture, and depth of seed burial on the emergence of redstem filaree. Emergence occurred from 5 to 30 C but was optimal at 5 to 15 C. Redstem filaree emergence was optimal in moist soil with water contents of -0.03 to -0.28 MPa. Emergence progressively decreased as soil moisture was lowered below these levels, with less than 25% emergence attained at -1.53 MPa regardless of soil temperature. Almost no germination was observed in warm (30 C), dry (-1.03 to -1.53 MPa) soils. Rate of emergence was affected more by soil temperature than by moisture. A decrease in temperature from 20 to 5 C increased the time to reach 50% emergence by 6 to 8 d but a decrease in soil moisture from -0.03 to -1.53 MPa increased the time to reach 50% emergence by only 1 to 2 d. Emergence was greatest at soil depths of 1 cm or less. No emergence occurred at depths of 8 cm or below.