effect of different directions of sampling on the precision distribution map of weeds

understanding the spatial distribution of weeds would provide good results for the commercial applications of future research programs, development forecast desirable of yield loss and understanding the processes that cause changes in spatial and temporal distribution weeds. in this order an experiment was conducted in 1388 to find the effects of biological interactions, climate and agricultural operations on the spatial distribution weeds of the sugar beet field and change of the angle of quadrat for sampling weeds. sampling weed was taken in four-leaf stage of sugar beet by quadrates of (0.2m× 0.4m) in the intersection of (7m×7m) square grids. quadrates were rotated at 0, 45, 90, 135 degree angles, respectively perpendicular to row plowing and clockwise. our results showed that weed distribution maps by angle of zero degrees showed highest density of weeds to reach the economic threshold. also component of the variogram showed that the distribution pattern of weeds changed at different directions. different types of weeds were every high dispersion according to sampling angle. elongation patches direction was dependent on weed management operations performed in the years ago and morphological characteristics of weeds.