Introduction: The production of oilseeds is one of the main sources of protein and energy and a supplier of edible oil needed by human society. Considering the shortage of oil and the trend of increasing vegetable oil consumption in the country, sunflower cultivation in arid and semi-arid regions can play an important role in providing the country with the oil it needs. Studies have shown that sulfur and fertilizers containing manganese, zinc, and iron, in addition to meeting the plant's nutritional needs; play a significant role in the quantitative and qualitative production of sunflowers. Fertilizer research projects on sulfur in oilseed crops are carried out in accordance with the precise principles of balanced nutrition to achieve high yields, and in Iran, due to the calcareous nature of the soils and the modifying role of sulfur, this research should be more serious. Sistan and Baluchestan province in Iran, due to its suitable potential for oilseed cultivation, can be one of the poles for the cultivation of these plants, and the cultivation of oilseed crops such as sunflower in this region is justified. In this regard, the aim of the present project was to work on the fertilization requirement of this important oilseed plant in order to determine both the yield potential and the fertilization response of this plant under the conditions of Zahedan in Iran.

Materials and Methods:

In order to investigate the effect of sulfur and some micronutrients on yield and yield components of sunflower, an experiment was conducted in the 2021-2022 crop year in a field in the Lakhshak region of Zahedan, Iran in the form of split plots basis in a randomized complete block design with three replications. In this experiment, sulfur was investigated at two levels (sulfur application and non-application) and micronutrients were investigated at five levels (non-application, iron, zinc, manganese and iron + zinc + manganese). Foliar application of each of the trace elements from the source of iron chelate, zinc chelate and manganese chelate was done at a concentration of one in a thousand. The time of foliar application was during the stem formation and flowering stages.

Results and discussion:

The results showed that plant height increased with the use of all levels of micronutrients and sulfur, and the highest height was achieved in the iron fertilizer and iron+zinc+manganese combined fertilizer treatments with an increase of 18.24 and 23.38 percent, respectively. Sulfur application significantly increased the 1000-grain weight compared to non-application, so that the 1000-grain weight increased from 79.93 g to 88.80 g, an increase of 11.10%. Considering the significant interaction effect of sulfur on micronutrients for grain and oil yield, in the absence of sulfur application, the greatest effect of these traits was obtained from the application of iron+zinc+manganese, while in the presence of sulfur, the application of all levels of micronutrients as well as the absence of micronutrients increased grain and oil yield to a statistically similar extent.

Conclusion: The results of this study showed that using all levels of micronutrients as well as sulfur had a positive effect on the studied traits. Among the elements used, manganese had the greatest effect on the quantitative and qualitative characteristics of sunflower due to its essential roles in physiological processes. Overall, it is recommended that sulfur application alone or in combination with iron+zinc+manganese micronutrients be used to increase the grain and oil yield of Azargol sunflower cultivar.