Beneficial nanoparticles are at the leading edge of the rapidly developing field of nanotechnology. Nanotechnology applied to nanofertilizers could play a fundamental role in improving the availability of plant nutrients under unfavourable environmental conditions. To evaluate the effects of different levels of nitrogen fertilizer (0, 75, and 150 kg ha–1) and nanostructured micronutrients (Zn, Fe, Cu) on the seed yield of spring safflower, a study was carried out in highland region of Baneh, Iran. Specific objectives were to assess the effects of combined application of nano-chelated micronutrients and nitrogen on safflower under rainfed conditions. Assessments of morphological traits revealed that application of nitrogen at the rate of 75 kg ha–1 significantly increased the plant height, canopy spread, stem diameter, and plant dry weight. Also, ground cover, canopy spread, capitulum diameter, and the number of the secondary branches were considerably affected by nano-chelated micronutrients, so the highest values were observed in the plants grown with the application of zinc and copper. Results showed that the effects of interaction of nitrogen and micronutrients were significant for the biological yield, seed number, 1000-seed weight, the percentage of unfilled seeds, and seed yield. A comparison of combined treatments showed that the best performance was recorded for plants grown with the application of N0-Zn, N75-Zn, and N150-Cu. The results of the present experiment agreed with the conclusion that utilization of nitrogen may affect the efficiency of micronutrients. Altogether, the results suggested that the application of intermediate levels of nitrogen fertilizers along with nano-chelated Zn can improve safflower production under rainfed condition.
