health assessment in wheat (triticum aestivum) fields using weeds biodiversity, yield and pesticides application (a case study in qaresoo basin-gorgan county)

this study was aimed to assess wheat-grown fields health in gharessoo basin, golestan province, iran, using 79 fields in 8 villages in 2010. the samples were taken by quadrates. the number and the type of weeds were recorded at genera and species levels. in parallel, management data were recorded by questionnaire. species richness was defined as species number and shannon-wiener index, simpson’s index of diversity and reverse simpson index were used as weeds biodiversity assessment indices. wheat fields map were detected by landsat 5 satellite images by remote sensing techniques. digital elevation model also was provided from 1:25000 digitized maps. slope and aspect layers were provided by dem and were reclassified. climatic, biodiversity and yield interpolated layers also were provided using multiple regression models. all of these layers also were reclassified. the regions with higher yield than mean values and lower weed biodiversity indices were considered as healthy. also, the fields with lower pesticide application than golestan application mean (1.45 lit. ha-1) were considered as healthy. a data mining method (crt) was used to assess management options effect on weeds biodiversity indices and yield in studied fields. our results revealed that just 44 percentage of cultivated lands (2064 ha) and just 11 percentage of studied fields (7 fields) were healthy in respect to yield, weeds biodiversity and pesticides application.