The effect of light during and after soil cultivation with different tillage implements on weed seedling emergence

The purpose of this study was to investigate the role of sunlight perceived by weed seeds during and after soil cultivation with moldboard and chisel plows on induction of seed germination. Daytime cultivation with a moldboard plow increased weed seedling emergence by as much as 200% above the levels recorded following nighttime cultivation; however, the magnitude of this promotion varied depending on season and field history, and occasionally it was nil. In contrast, when a chisel plow was used in primary tillage, no differences in seedling emergence were observed between daytime and nighttime cultivation. The absolute germination level in plots cultivated with a chisel plow was at least 200% greater than in plots cultivated with a moldboard plow. This observation suggests that microenvironmental factors other than light played an important role in promoting seed germination in chisel-plowed plots. Covering moldboard-plowed plots with opaque plastic immediately after cultivation did not reduce weed seedling emergence compared to plots that were either covered with transparent film or left uncovered. Our results suggest that only the light stimulus perceived by the seeds during soil cultivation is effective in triggering germination.