Evaluation of Different Nitrogen Fertilizer Sources on Relative Abundance, Density and Biomass of Weeds in Safflower (Carthamus tinctorius L.)

In order to investigate the effect of different sources of nitrogen fertilizer on the relative frequency, density and biomass of safflower, a factorial experiment was conducted in a randomized complete block design with three replications located in the research farm of faculty of agriculture university of Jiroft in 2018-2019 year. The first factor at two levels included the use of manure and non-use of manure, the second factor included different nitrogen fertilizer sources at five levels of control, urea fertilizer, urea fertilizer with sulfur coating, ammonium nitrate, nitroxin and nano nitrogen. The results showed that in all three stages of sampling weeds, Clover (Trifolium repens L.) and Umbrella sedge (Cyperus rotundus L.) weeds had the highest and Bermudagrass (Cynodon dactylon) and Sorrel (Rumex crispus L.) had the lowest relative abundance. Different sources of fertilizer had a significant effect on biomass weeds of clover, umbrella sedge, common mallow and other weeds during three sampling stages. Based on the results of mean comparison, the highest biomass was obtained of clover weed in the first stage in the treatment of manure with chemical fertilizers urea (17.04 g). The lowest biomass was obtained in no manure in control (6.47 g) and nano nitrogen fertilizer (4.63 g). Shannon and Margalef indices in the first stage of sampling 0.96 and 0.94, the second stage of sampling 0.79 and 1.06 and the third stage of sampling 0.63 and 1.11 respectively in the treatment of manure was more than to non-use manure. Sources of urea and urea fertilizers with sulfur coating had higher weed diversity index than other treatments. According to the results of this study, it is suggested to use biological sources of nitrogen in order to prevent weed infestation and competition with the target plant.