THE EFFECT OF LIGHT ENVIRONMENT DURING TILLAGE ON THE RECRUITMENT OF VARIOUS SUMMER ANNUALS

Weed seeds can require an exposure to light for induction of germinati on. Conducting tillage operations at night and thus preventing the pho toinduction of germination has been proposed as a means to reduce weed emergence in agricultural systems. This research was conducted to eva luate night tillage as a weed management option and to determine which tillage operations have the greatest effect on light-mediated recruit ment. Weed emergence was evaluated after conducting factorial combinat ions of day and night moldboard plowing and disking in the springtime from 1992 through 1995. The light environment during disking generally had a slightly greater effect on emergence than the light environment during plowing. Emergence of pigweed species and giant foxtail was, a t most, 30 to 55% higher following day vs, night disking. Emergence of other weeds was not affected by the light environment during tillage. We conclude that night tillage may not be a viable approach to weed m anagement due to insufficient reductions in weed emergence associated with night tillage and the high degree of variability in the recruitme nt response to light conditions during tillage.