سیده فریبا خاموشی

In order to identify and determine weed population in sugar beet fields, 92 fields from five counties of Kermanshah province in Iran were selected and evaluated at two growing stages (early May and late September) in 2014. The weed population indices were calculated by counting the number of weeds separated on othe basis of genus and species. For all fields, the latitude, longitude and altitude were recorded using GPS device. Eighty-five weed species belonging to 31 families were identified in different sugar beet fields. The dominant broad-leaf weeds identified at the beginning of the growing season (first sampling stage) were lamb's quarters (Chenopodium album L.) and field bindweed (Convolvulus arvensis L.) with 189.22 and 124.09% dominance index, respectively, whereas at the second sampling (late September), the dominant broad-leaf weeds identified were lamb's quarters (Chenopodium album L.), pigweed (Amaranthus retroflexus L.) field bindweed (Convolvulus arvensis L.), and cocklebur (Xanthium strumarium) with 207.92, 194, 111.22, and 107.93% dominance index, respectively. Green foxtail (Setaria viridis L.) was the dominant narrow-leaf weed in both samplings at the beginning and end of the growing season with 79.73 and 176.35% dominance index, respectively.