Investigating the Interaction of Different Irrigation and Nitrogen Fertilizer Levels on The Yield of Forage Corn in Khorramabad

This research was conducted in order to investigate the interaction of different levels of irrigation and nitrogen fertilizer on the yield of Forage Corn in Khorramabad. The experiment was conducted as factorial in a randomized complete block design with three replications. The first factor consisted of four irrigation levels including I125 (125 Percent of water requirement), I100 (100 Percent of water requirement), I75 (75 Percent of water requirement), and I50 (50 Percent of water requirement) and the second factor consisted of three levels of nitrogen fertilizer including N400 (400 Kg/ha), N250 (250 Kg/ha), and N100 (100 Kg/ha). Based on the evaporation pan method, the total irrigation requirement for treatments I125, I100, I75 and I50 during the period were 761, 642, 524 and 406 mm, respectively, which were more than the amount of water requirement reported in the national water requirement document of plants.The result showed that the maximum amount of wet and dry matters, plant height, leaf area index which were 80 and 21.2 tons per hectare, 9595 mm2 and 220 cm, respectively, were obtained in I125N400 treatment, which had a significant increase (5 Percent) compared to the control treatment (I100N250). The minimum amount of these traits which were 30 and 10.64 tons per hectare, 7096.133 mm2 and 100 cm, respectively, were obtained in I50N400 treatment, which had a significant decrease (5 Percent) compared to the control treatment (I100N250). It was found from the results of this research that at the levels of I125 and I100, the values of wet matter and leaf area index were increased as the amount of nitrogen fertilizer increased. At irrigation levels of 75 Percent and 50 Percent of water requirement, increasing the amount of fertilizer did not cause significant changes in the measured traits. In this research, the maximum value of water productivity for wet and dry matters was obtained in I100N400 treatment with values of 10.9 and 2.91 kg/m3, respectively.