Study of the Spatial Relationship between Seed Bank and Weed Populations and the Distribution Pattern of Weeds in Corn Fields during the Growing Season

An experiment was conducted in the research field of the Islamic Azad University of Karaj in 2007 to study the relationship between weed seed bank at the start of the growing season and weed populations during the growing season, as well as to study the distribution pattern of the weeds. In this experiment, seed bank sampling was carried out at the beginning of the growing season (after planting the corn crop), and sampling of the populations of weed seedlings was performed at the four-leaf stage, at the 8 – 10 leaf stage, and at tussle formation, in 96 places using the networking method. Then, on the basis of the abundance of weed seeds in the soil and the seedlings germinated at different sampling stages, the relationship between seed bank and seedling populations was investigated; and it was found that there is a significant relationship between seed bank at the start of the growing season and the population of weed seedlings during the growing season. The greatest correlation (r=0.83) was that between Flora 1 and the seed bank, indicating that weed density at this stage (the four-leaf stage of corn) was at its maximum, and that it was the best time for weed control. Next, the field was mapped with the help of the GS+ (GS plus) software, and the isotropic and anisotropic diagrams of each of the species were plotted with the help of semi-variogarms. Results obtained showed that the distribution pattern of weed species in the field was patchy, with different species having different patch diameters. Finding the correlation between seeds and floras makes it possible to determine the best time for weed sampling and weed control.