Weed Mapping for Dryland Chickpea (Cicer arietinum L.) Fields in Kurdistan Province using Geographic Information System

Weeds on dryland chickpea fields are the main yield loss factor. Therefore, weed identification is the most important operation for weed management. Chickpea is one of the most important crops in Kurdistan province of Iran. Kurdistan province ranked forth and first in area under cultivation of chickpea and its production in Iran, respectively. This study was carried out in order to identify weed species, determine the dominant weeds, and develop the distribution maps of dryland chickpea fields in Kurdistan province.

Based on cultivation area of chickpea and the topographic condition of Kurdistan province, 33 fields were randomly selected in 2013 and weed species were determined in 5 counties, e.i., Dehgolan, Kamyaran, Divandareh and Saqez. The selection of the fields in each county was done based on acreage of chickpea in the county. Weed identification were done at each region, during three leaf and podding stages of chickpea. These periods were chosen because of easiness identification of weed species at these stages and the possible recording of weed control practices applied on fields. Demographic indices of weed species were calculated, and then the dominant weeds were determined. Also the latitude, longitude and altitude of each sampling point using GPS were recorded. By using these data, the distribution maps of the dominant weed species in ArcGIS area were produced.

The number of weeds observed in this study during period of three leaf stage of chickpea were 52 species mostly from Astraceae, Poaceae, Apiaceae and Caryophyllaceae families and the most important weeds in surveyed area based on abundance index were catchweed bedstraw (Galium aparine L.), field bindweed (Convolvulus arvensis L.), shepherd,s needle (Scandix pecten veneris L.), salsify (Tragopogon graminifolius DC.), volunteer winter wheat (Triticum aestivum L.), dove-foot geranium (Geranium molle L.) and great bur parsley (Turgenia latifolia (L.) Hoffm). The number of weeds observed at podding stage were 58 species with most abundant families of Astraceae, Poaceae, Brasicaceae, Apiaceae and Caryophyllaceae and the most important weeds based on abundance index were field bindweed, salsify, sun spurge (Euphorbia helioscopia L.), shepherd’s needle, catchweed bedstraw, dyer’s croton (Chrozophora tinctoria (L.) Juss.) and smell melon (Citrolus colocynthis L.). The most dominant grass weed species was volunteer winter wheat (Triticum aestivum L.) because of the common crop rotation (Chickpea-Winter wheat). The distribution map of the dominant weeds showed that field bindweed, salsify, sun spurge, shepherd’s needle and catchweed bedstraw were seen in all surveyed counties but great bur parsley in Sanandaj, volunteer wheat and sun spurge in Kamyaran and smell melon in Divandareh and Dehgolan were not seen. The time of tillage for preparing of chickpea seedbed is spring in Kurdistan province and narrow leaf weeds emerge often in fall but they produce numerous seeds. The annual weeds had the highest population on chickpea fields because of the annual soil disturbance, having similar requirements with the annual crop and abundant seed production. Although, perennial weeds, i.e., field bindweed and salsify caused more problem for the farmers because of herbicides limitation for this crop and tremendous energy required for hand weeding of this crop for weed control in this province. It is not easy to control weeds with rhizome and thorn. To determine the abundance index, frequency and uniformity had a higher values than the mean field density. Higher values for these three parameters for a particular species indicated that these species were well-suited with the soil and climate conditions in which it was growing, while higher rates of the mean field density for certain species indicated that they had a higher competitive or reproductive ability than other species.

The management of weeds on dryland chickpea fields in Kurdistan province is not satisfactory. The results showed that field bindweed and salsify were dominant weeds in this study area with high density due to particular weed management approaches. Therefore, farmers should change their weed management strategies in these regions. We will be able to make decision based on previously developed weed distribution maps. Better knowledge of the past and present is a key component for the improvement of the planning that will effect Iran’s agricultural division in the years ahead. Findings from this study and similar studies are helpful to establish new ways for the sustainable economic development in Iran’s agriculture.