investigation of nutsedge (cyperus spp) seed bank and seedling relationships using geostatic relations

a field experiment was conducted to investigate the spatial distribution of nutsedge (cyperus spp) during rice growing season using geostatic in 2011 at sari agricultural sciences and natural resources university. at the first field was divided into 36 grids (2.5×2.5 meter) after the final preparation. grid intersection points were determined and marked. all samples were taken from these points during the crop season. the sampling from seed banks was performed in two stages before the field preparing and after the rice harvesting. also weed density were determined using square quadrate (50×50 cm) in three different dates during the growing season. all data were transferred to the rockwork99 software for drawing maps of weed and seedling distribution. the results showed that the highest amount of weed population was belong to nutsedge. there was strong and medium spatial correlation as spherical and exponential variogram model between weed and seedling nutsedge at all stages of sampling. meanwhile, the weed seed bank was patches with different sizes and densities according to spatial distribution maps. seed bank patchy pattern at the beginning of season was in accordance with seed bank at the end of season and seedling germination pattern. therefore the seed bank maps can be used as information database of seedling germination. the results of this study showed that spatial distribution monitoring in soil depth (0-10, 10-20 and 20-30 centimeters) can be a valuable tool for prediction of weed behavior and increases our understanding about dynamics of weed populations