Study of flora and structure of weed communities of saffron (Crocus sativus L.) fields in Khorasan Razavi province

The Khorasan Razavi province is the center of saffron production in Iran and the world. Among factors affecting saffron gap yield, weeds are the most important one. However there is no compiled information about saffron weed flora population and its structural characteristics in the Khorasan Razavi province. In order to identify and determine the density and frequency of weed species on saffron fields in the Khorasan Razavi province, 118 fields in 6 counties during two years (2014 and 2015) were selected based on the cultivation area and yield per area. In each field, weed species were counted in each sampling point and weed population indices including mean relative density, relative uniformity and frequently were calculated and latitude and altitude were recorded by GPS. By using recorded data, population indices of different weed species in the studied saffron farms including mean relative density and relative frequency of species were calculated.  During 2 years, a total of 52 weed species were identified and observed within the saffron fields. Between plant families, Brassicaceae, Asteraceae, Poaceae, Fabaceae and Charyophilaceae were the most abundant families, respectively. The results showed that the highest and lowest number of weed species belong to Kashmar and Gonabad counties, respectively. Based on the frequency index, the important annual weed species on saffron fields of the Khorasan Razavi province wereMouse Barle (Hordeum murinum) and London Roket (Sisymbrium septulatum) and perennial species were Hoary Cress (Cardaria draba) andCommon yarrow (Achillea millefoliam)