To evaluate the effect of different micronutrients (Mn, Fe, Zn) and farmyard manure (FYM) on the vegetative, phenological, and achene yield components of sunflower a field experiment was conducted in Maragheh, North West of Iran during the growing season 2018–2019. The treatments were arranged in a split-plot design- with three replicates. The main plots assigned to two levels of FYM (0 and 20 t ha−1) and sub plots assigned to the recommended dose of three micronutrients (Mn, Fe, Zn). The results revealed significant improvements in the growth and yield of sunflower due to the main and interaction effects of farmyard manure and inorganic fertilizer application. The highest number of leaves and the highest leaf area was observed in a plant grown by FYM + Zn. However, there was no significant difference between micronutrients under inorganic condition (without FYM application). The highest leaf relative water content (RWC), plant height, internode distance, and chlorophyll was recorded for plants grown by Fe or Zn under FYM applied condition. Application of FYM and micronutrients reduced the number of days to flowering. However, the application of FYM significantly delayed plant maturity. Achene number per head, 100-achene weight, achene length, achene width, achene oil percent, achene yield, and harvest index significantly increased with the application of FYM and the best performance was in a plant grown by FYM + Zn and FYM + Fe. The percentage of hollow and empty achene was significantly reduced by the application of FYM. Combined applications of FYM and micronutrients has become an increasingly common practice.
