Effects of Tillage Systems, Zinc, Iron and Sulfur on Grain Yield of Safflower (Carthamus tinctorius L.)

Seed yield in soybean is a complex trait and is influenced by multiple genetic and environmental factors. Safflower is one of the oilseeds adapted to a wide range of soil conditions, but micronutrients deficiencies cause a decrease in its grain yield and quality. Hence, an experiment was conducted as a split factorial based on randomized complete block design with three replications at Agricultural and Natural Resources Research Center of Arak, Iran in 2019. Three tillage methods (including no tillage, low tillage and conventional tillage) were considered as the main plots and fertilizer treatments (including 1- Control, 2- Zinc, 3- Iron, 4- Sulfur, 5- Zinc + Iron, 6-Zinc + Sulfur, 7- Iron + Sulfur, and 8- Iron + Sulfur + Zinc) were considered as sub-plots. Results showed that there were significant differences between the fertilizer treatments in terms of seed yield, flower yield, seed weight per head, number of heads, number of seeds per head, percentage of seed protein and seed oil. In the treatment of tillage methods, thousand seed weight and linoleic fatty acid had significant differences. Interaction effects of soil tillage methods X fertilizer were significant on number of heads and linolenic acid. Fertilizer treatment of iron + sulfur + zinc had the highest seed yield (i.e. 1391 kg ha-1), flower yield (i.e. 183.7 kg ha-1), 1000 seed weight (i.e. 45.8 g), seed weight per head (i.e. 1.27 g), number of heads (i.e. 7.9), protein percentage (i.e. 21.2%) and seed oil percentage (i.e. 26.5). Results of this research showed that application of micronutrient elements by increasing the yield components, particularly 1000-seed weight, number of heads, and the weight of seeds per head led to increases in seed yield, oil percentage and protein percentage of safflower seeds. Though, tillage methods had no significant effect on safflower seed yield. According to the results of this experiment the use of zinc, sulfur, and iron fertilizers along with the method of low tillage can help to increase the grain yield and quality of rapeseed.