GIS Applications in Surveying and Mapping of Rice Weeds in Guilan Province, Iran

Present study was carried out in rice farms of Guilan province for mapping and weed distribution using Geographic Information System (GIS) technologies for a period of three years (2014-2016). Echinochloa crussgalli was the more important species in 10 regions of Guilan province. The Langarud and Rudsar regions each with 47 species and Anzali and Shaft with 25 species (with 71.2 and 37.9 percent, respectively) had the highest and lowest species diversities, species diversity in 2015 was more than 2014 and 2016 years. The frequency of weed species in Guilan rice farms in 2014-2016 was 3.38, 3.87 and 4.82percent, respectively. Cyperus esculentus and P. distichum were the most abundant species with 9 and 8 plants/m², respectively. Echinochloa crussgalli and C. difformis with a density of 5 plants/m2. Weeds were non-uniformly distributed in various families including Cyperaceae, Poaceae, Lythraceae, Polygonaceae, Asteraceae, and Salviniaceae that accounted for 36 species (54.5 percent). Accurate and specific weed maps are the key to achieving all the benefits of weed management. When in an area the distribution and consumption of inputs is based on accurate information from the weed composition of the farms in that area, the efficiency of these inputs is improved and weed damage is reduced.