LAUSR

• Lodging in maize results in grain yield reduction. The purpose of the experiment was to investigate the effects of uniconazole (UCZ) and nitrogen (N) rates under medium and high plant population on lodging resistance and yield attributes of maize. • We conducted an experiment, and UCZ was applied to seeds at concentration of 0 (U0 ) and 25 mg kg-1 (U25 ) with three different N rates; 0 (N0 , no N application), 150 (N150 ), and 225 (N225 ) kg ha-1 under plant population of 75,000 (D1 ) and 105,000 plants ha-1 (D2 ). • UCZ application under different N rates and plant population affected the lodging resistance and yield attributes of maize. The diameter, plumpness, rind penetrating and bending strengths of the internodes were enhanced with UCZ and N application under medium and high plant population, where there maximum values were obtained with U25 N150 D1 . Internodes length was increased under high plant population and higher N rate, whereas UCZ reduced the internodes length, where maximum internodes length was obtained with U0 N225 D2 . The plant height, center of gravity height, ear and height above ear-bearing node were higher under high N rate and UCZ reduced it significantly. UCZ, N rates and plant population enhanced lignin accumulation in the third internode and ear-bearing internode, where there maximum values were obtained with U25 N150 D1 . Yield and yield attributes were also improved by UCZ, N rates and plant population. • Treatment U25 N150 D2 significantly improved grain yield of maize compared with the other treatments.