• haroon khan The University of Agriculture Peshawar, Department of Weed Science
Keywords: Weeds distribution, relative density, relative frequency and importance value of weeds


Weeds interference with crops and native useful plants, causing negative impacts on crop production and biodiversity. Weeds being more adaptable to changing climate establish easily into new areas becoming invasive over the native vegetation. To investigate further the adaptability of invasive weeds and their status among the native plant community a field survey was carried out from July – September, 2017 at New Developmental Farm (NDF), Malakandher, The University of Agriculture, Peshawar to record weeds species composition. Data was sampled from three different sites i.e. field crop area, non-field and orchards with a quadrate randomly thrown 50 times at different locations. A total of 39 weeds species from 16 families (14 dicot and two monocot) and 36 genera were identified. Dicots were dominant as compared to monocot. The major monocot family poaceae contributed 10 species while in dicots Asteraceae took the lead with 6 species, followed by Euphorbiaceae with 3 species. The rest of the plant families include Aizoaceae, Amaranthaceae, Convolvulaceae, Cucurbitaceae, Cyperaceae, Euphorbiaceae, Malvaceae, Nyctaginaceae, Oxidillaceae and Plantaginaceae. Among the weed species 27 were annual and the rest (12) were perennials. Annuals were reported from all the three sites, while perennials were found in non-field area i.e. irrigation canals, field ridges, orchards and undisturbed waste areas. Data regarding absolute and relative density, frequency, relative frequency and importance valve of weeds of the area were recorded by quadrate method. Cynodon dactylon had the highest relative density (27.21%), followed by Digiteria sanguinalis (14.87), Cyperus rotundus (12.96) and Euphorbia prostrata (5.12) relative density, respectively. Parthenium hysterophorus L. an invasive alien weed was recorded in almost all the localities with a weed density of 2.6 m-2 in non-field area especially, followed by 0.85 m-2  in field crop and 0.8 m-2  in orchards and with a mean density of 1.42 m-2 and a relative density % of 1.52 across all locations. Similarly another invasive weed Broussonetia papyrifera was recorded in non-field area only with lowest mean relative density of 0.07%. Mean distribution data showed highest relative frequency for C. dactylon (13.66 %) followed by D. sangunalis (10.22), C. rotundus (7.86) and S. halepense (7.23), respectively. Alhaji maurorum, Eclipta alba, Cucumis callosus, B. papyrifera, Withania somnifera and Boerhavia diffusa took the smallest relative frequency of 0.38 % at most of the locations studied thereby indicating them as insignificant among the weed flora of the study area. Importance value data revealed that C. dactylon, D. sangunalis, C. rotundus and S. halepense having IV % of 34.03, 19.99, 16.89 and 10.17, respectively. Looking at the overall distribution of weeds flora in NDF Malakandher during the summer season C. dactylon is distributed on road sides, field ridges, irrigation channels, agricultural fields, orchards and waste lands, while P. hysterophorus being an invasive weed showed increasing trend compared to its earlier status evident from previous study.