Abstract The positive effects of nitrogen application and mycorrhizal inoculation on safflower growth and development has been shown in numerous studies. However, information is not available regarding the interaction effects of maintaining wheat residue in farm simultaneously with nitrogen fertilizer application and mycorrhizal inuculation. Accordingly, this study was conducted to eva‎luate the application of nitrogen fertilizer and mycorrhizae under maintaining of wheat residues on the safflower plants (Faraman cultivar) eva‎luated in a farm located in Mobarakeh city, Esfahan, Iran, during 2024. Treatments included different levels of plant residues (0, 2000, and 4000 kg/ha), nitrogen fertilizer (30, 60, and 90 kg/ha in the form of urea) and mycorrhizal inoculation (with and without). Treatments were arranged as split-split plot experiment based on a randomized complete block design with three replications. The measured traits were the percentage of mycorrhizal colonization, germination rate, and concentrations of iron, zinc, nitrogen, phosphorus, potassium, photosynthetic pigments and grain yield and yield components. The results showed that mycorrhizal inoculation and plant residue application increased germination rate by 7 and 10%, respectively. Mineral nutrients were increased by nitrogen fertilizer, mycorrhizal inoculation and plant residue. The interaction effects of nitrogen and plant residue were significant on Fe and K concentrations so that, regardless of mycorrhizal inoculation, the highest concentration of these elements was obtained by the application of 60 kg nitrogen under 4000 kg residue. According to three-way interaction analysis results the highest concentration of Zn was achieved by the use of 60 kg nitrogen under residue treatment (regardless of mycorrhizae application). The interaction of residue and mycorrhizae was significant on Fe concentration. The highest concentration of Fe was observed in the inoculated plants under 4000 kg residue. Considering nitrogen and mycorrhizae interaction, the highest P was obtained by 60 while the highest Fe by 60 and 90 kg nitrogen application in the inoculated plants. All three experimental treatments increased the concentration of N in the plants. The interactions of nitrogen with residue and nitrogen with mycorrhizae were significant on the cholorophyll content. The highest cholorophyll content was seen in the inoculated plants under 90 kg nitrogen application but there was no significant difference among residue treatments in this regard. Grain yield and its components including number of branch and heads per plant, number of grains per head and 1000 grain weight were improved by the application of nitrogen, residue and mycorrhizae. The highest grain yield was obtained under 4000 kg residue and 60 kg nitrogen application. The results of this study indicated that the maintenance of plant residue accompany with mycorrhizal inoculation through providing suitable condition for safflower plants can reduce the application of chemical fertilizer which is important in view of sustainable agriculture. Keywords: Safflower, plant residues, nitrogen fertilizer, mycorrhizae, nutrient concentration, photosynthetic pigments, grain yield.

مرتضي زاهدي

حميدرضا عشقي زاده , محمدعلي حاج عباسي جورتاني