Study on Weed population indices and producing weed maps in dryland wheat fields of Zanjan province

An experiment was conducted to identify weed species and determine the abundance of each species over the Dryland wheat fields of Zanjan province, 342 wheat fields in five counties during 2000 to 2005 were investigated. Population indices were calculated by counting number of weeds species in each sampling quadrate. In each field, longitude, latitude and elevation were recorded using global positioning system (GPS) to produce weed species maps in Geographic Information System (GIS) over the studied area. Based on the results 97 species were recorded over the province out of which 62, 64, 70, 51 and 70 weed species collected from Abhar, Eijrood, Khodabandeh, Mahneshan and Zanjan counties respectively. The broadleaved weed species regarding their importance were: knotweed (Polygonum aviculare L.), tuberous geranium (Geranium tuberosum L.), spurge (Euphorbia sp. L.) and alyssum (Alyssum sp. L.) respectively whereas dominant grass weed species were goatgrass (Aegilops sp. L.), barley (Hordeum sp. L.), and squarosa couch grass (Eremopyrum sp. [Spreng.] Nevski.) respectively. Considering damage prior to harvest, field bindweed (Convolvulus arvensis L.), was the most important weed followed by: safflower (Carthamus oxycantha Bieb.), Canada thistle (Cirsium arvense [L.] Scop.) and hoary cress (Cardaria draba [L.] Desv.) respectively. The families of Asteraceae (chicories), Brassicaceae (cabbages), Fabaceae (legumes) and Poaceae (grasses) were the most diversed families of weed species.