Effect of crop rotation and chemical management on weeds seed bank in wheat fields in Khouzestan region

To evaluate the effect of crop rotation and chemical management on weed seed bank in wheat fields, a three-year experiment was conducted in split-plot design with three replications in Khuzestan province. Main plots were crop rotation (wheat-wheat-wheat, wheat-rapeseed-wheat and wheat-sugar beet-wheat) and subplots were chemical management (Untreated Control (UTC), chemical rotation and no chemical rotation (farmer program)). The results showed the change in crop rotation reduced the frequency ratio of weeds seed bank population in both evaluated depths (0 to 10 and 10 to 20 cm). Also, the combination of chemical management along with crop rotation significantly reduced weeds seed bank population. In the absence of herbicide application in the three years of experiment, the frequency ratio of winter wild oat weed seed bank population on the soil surface decreased from 2.20 to 1.48 with rapeseed and from 2.73 to 0.63 with sugar beet planting, however, in the case of non-crop rotation, the frequency of wild oat seeds in the seed bank increased. This trend was also evident in the total weed seed bank population.