Date of Award:

1990

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Advisor/Chair:

Dr. Steven A Dewey

Abstract

Winter wheat stubble and dried plant residue in Conservation Reserve Program (CRP) fields were burned in the fall and spring to evaluate effects on jointed goatgrass (Aegilops cylindrica Host.) seed survival and germination. Laboratory studies were also conducted to determine minimum temperatures and heat duration needed to reduce jointed goatgrass seed viability. Maximum air temperatures attained during various field burns reached from 74 C to over 700 C. Temperatures 2.5 em above the soil surface remained above 400 C for over 10 seconds and above 600 C for 2 to 8 seconds in burning CRP stubble. Results for the winter wheat stubble location were similar with temperatures sustained above 400 C for over 30 seconds.

Seed exposure in the lab to 400 and 600 C flames for 1 second reduced germination to 20 and 15 percent, respectively. Germination was reduced to zero with exposures of 10 seconds or more. Oven temperatures of 150 C reduced germination to 85, 57.5, 17.5, 0 and 0 percent for exposures of 20, 30, 60, 120 and 300 seconds, respectively. At 275 C oven temperature germinability dropped to 50% after a 10 second exposure and 0% after a 20 second exposure.

Jointed goatgrass plant populations were reduced 54 to 92% after field burning in the spring or fall. Fall burning provided 70 to 85% control of goatgrass the following spring. In non-burned non-disked plots over 90% of emerging plants germinated from seeds on the soil surface. In burned non-disked plots few seeds germinated from on the surface, with 80 to 90 percent of surviving plants having germinated from buried seed.

Herbicides provided limited control of jointed goatgrass. None of the herbicides provided greater than 50% control.

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