Evaluation of yield and yield components of low n maize (zea mays l.) varieties under low and high nitrogen conditions

Field studies were conducted at the teaching and research farm of the Osun State University Ejigbo Campus, Osun State, Nigeria, during the 2015 and 2016 cropping seasons to determine the agronomic performance of low N maize varieties under two nitrogen conditions (low and high). The aim of this experiment was to determine the response of low N maize to two levels of nitrogen fertilizer. Ten low N maize varieties were used in this study. Low and high-N conditions of the soil was induced by application of urea fertilizer at the rate of 30 and 90kg ha-1 of nitrogen .The experiments were laid out in a randomized complete block design with three replications. High nitrogen application significantly improved maize vegetative growth, yield components and grain yield. The use of 90 kg ha-1 of N gave the highest maize plant height,  and number of leaves per plant, as well as grain yields of 3.50 and 3.58 tha-1 was obtained with the application of 90 kg ha-1 of N in 2015 and 2016 cropping seasons, respectively. The result indicated that application rates of nitrogen (kg ha-1 of N) improved growth attributes of all the varieties with SINT MAR 20CA LARGA gave maximum grain yield that is not significantly different from 72PBPROLC3SYN. Key words: Plant height, agronomic performance, low N maize, nitrogen levels.