OICC Press Journal of Crop Nutrition Science 2538-2470 9 1 2023 03 30 Investigating the Effect of Nitrogen and Nitroxin Biological Fertilizer on Quantitative and Qualitative Characteristics of Dual-purpose Barley (Hordeum vulgare L.) Forage 58 70 EN Najmeh Haghighatzadeh Msc. Graduated, Department of Agronomy, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran. Mani Mojaddam Assistant Professor, Department of Agronomy, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran. Journal Article 2023 03 30 BACKGROUND: Optimum uses of nutrients is the most important factor in agricultural systems due to limitations of nutrients especially nitrogen.OBJECTIVES: Current study was done to assess the consumption of different amounts of nitrogen and Nitroxin biological fertilizer on crop production of dual-purpose barley forage.METHODS: This research was conducted in the cropping year of 2013-2014 in Ahvaz city in the form of a split plot using randomized block (RCDB) with three replications. The investigated treatments include the use of pure nitrogen at three levels (including the use of 50, 100 and 150 kg.ha-1) and the use of Nitroxin biofertilizer at three levels (including no use of nitroxin (control), use of 2 and 4 liters per hectare), were placed in the main and sub plots, respectively.RESULT: The results showed that the effect of different amounts of nitrogen fertilizer and nitroxin biofertilizer on leaf area index, dry forage yield, forage protein yield and seed protein percentage were significant. The highest leaf area index at the flowering stage (4.5), dry forage yield (2450.3 kg.ha-1) and forage protein yield (544.9 kg.ha-1) belonged to the treatment of 150 kg N.ha-1. The consumption of higher doses of nitroxin caused a significant increase in the leaf area index at the flowering stage, dry forage yield and forage protein yield, although there was no significant difference between the consumption values of 2 and 4 liters per hectare in terms of these traits.CONCLUSION: The interaction effect of the treatments on the studied traits were not significant, according to this, under the consumption of larger amounts of nitrogen (up to 150 kg.ha-1) or the use of biological fertilizer at the rate of 2 liters per hectare (considering the lack of significant difference with the consumption of 4 liters per hectare) can achieve quantitative and qualitative yield of forage in dual-purpose barley cultivation.