determination of weed spatial distribution based on damage threshold in two winter wheat (triticum aestivum l.) fields in shahrood region

estimation of weed damage threshold is essensial in site-specific weed control programs. this experiment was conducted to determine the spatial distribution of weeds damage threshold in two wheat feilds. data related to weed biomass and crop yield were collected from sampling at 120 and 135 points of the first and second fields respectively based on a 4×4 m grid at research field of agricultural college of shahrood university, in 2012. the damage threshold based on 10% yield reduction estimsted by models was 2.31 and 2.77 gr.m-1 of total weed dry weight in the first and second fields respectively. the results also showed that the trained rbf neural network had high capability in prediction of weeds biomass spatial distribution based on damage threshold of 0 and 10% yield reduction (with 99 % output, 0.99 coefficients and the average error of less than 1.58 and 1.3 respectively) in the first and second wheat fields. according to the experiment results, determination of saptial distribution of weed damage threshold using total weed s biomass can be used as an effective method in the mapping of weeds in site specific weed control programs.