Allelopaty may be hired as a sustainable approch for weed control in the field. Saffron is a medicinal plant with allelochemical properties which has a long history of production in Iran. In order to investigate the allelopathic action of saffron, two experiments were conducted in the Department of Agronomy and Plant Breeding of Isfahan University of Technology and Fozveh Research Center of Najaf Abad, Iran in 2012-2013. In the first experiment, aquous extraction of saffron was used to examine the allelochomical potential of 20 saffron genotypes obtained from different regions in Iran, including Hamedan, Nishapur1 (mian jolge), Nishapur2 (zyrjan), Nishapur3 (khujan), Nishapur4 (Qobyd), Sabzevar, Mashhad1 (Faizabad), Mashhad2 (Faizabad), Natanz, Khaf, Khorasan (chai bagh), Torbatejam, Kashan (mashhdardhal), Gonabad, Torbat heydaryeh, Birjand, Yazd (mahabad), Shiraz (estahban), Isfahan, Kashmar on three noxios weeds (weed seeds of Convolvulus arvensis, Descurania Sophia and Hordeum murinum ) . Aquous extracts were prepared from aerial parts of saffron in concentrations of 0, 3, 6, 12.5, 25, 50 and 100%. Seedling traits of the attributes of target species including radicle and plumule lengthes, radicale and plumule fresh weights, plumule dry weight, germination percent and velocity were measured. Experimental results showed that the effect of genotype and concentration and their interaction on measured traits were significant. This means that response of the target species to allelochemical effect of saffron varies with saffron genotype. Extract reduces all attributes differently. Genotypes "Khaf was proven to be the most allelopathic genotype, and genotype "Torbate jam" and " Nishapur (Zyrjan)" were found to leave minimal allelopatic effects on the target species. With increasing in aquous extracts concentration root and shoot length, root and shoot fresh weight, shoot dry weight and germination percentage of target species decreased. Maximum inhibition was observed at aquous extract concentrations of 100% and minimum inhibition was observed at aquous extract concentrations of 3% . The second experiment was designed to investigate the probably suppressing affect of saffron genotypes on the weed growth under natural field conditions. At the end of the second growing season of saffron, sampling was conducted in March 2012. Naturally occuring weed species included wild barley, flixweed, malcolm stock and filaree. Population density, shoot height, shoot fresh and dry weights of weeds were measured. The results of this experiment revealed that the saffron genotypes had a different effect on the weeds species. In a suchway flixweed had the greatest freqency, while filaree had less population. Key words : Allelopathy, aquous extract, saffron genotypes, growth inhibition
