Co-application of nano, chemical, and biological fertilizers has been recommended to increase quality and quantity of plants in sustainable production systems. Field experiments (factorial split plot experiment based on completely randomized block design) were conducted during two consecutive years to investigate the effect of nitrogen (nitroxin, urea, and nitroxin + 50% urea) and potassium (without fertilizer, soil and foliar application of potassium nano-chelate, and potassium dioxide) forms on grain yield, physiological traits, oil content, and fatty acids composition of sesame under water stress conditions (normal irrigation, irrigation up to 50% seed ripening and flowering (mild and severe stresses, respectively). Severe water stress was caused decreasing chlorophyll content, grain yield (25.4%), seed oil content (2.87%), and unsaturated fatty acid content, while it increased catalase and peroxidase activities, total carbohydrate, and saturated fatty acids content in compared to the control. As shown, the grain yield in the second year was more than the amount in the first year. The highest grain yield was achieved in co-application of 50% urea and nitroxin in combined with potassium dioxide under normal irrigation during the second year, which showed an increase of 42%, compared to the control treatment. Application of potassium fertilizer (nano or chemical) increased unsaturated fatty acids content in compared to the control treatment. While non-application of fertilizer had the highest saturated fatty acids content. Finally, the co-application of potassium fertilizer (nano or chemical forms) with nitrogen fertilizer (nitroxin + 50% urea) could alleviate the adverse effects of water stress on the studied traits.
