Response of maize (Zea mays L.) cultivars to different levels of nitrogen fertilizer

In order to study the effects of nitrogen levels on yield and yield components in maize cultivars, a split plot experiment based on randomized complete block design with three replications was conducted in 2008 at the Research Farm of Islamic Azad University, Branch of Ardabil. Treatments were arranged in a split plot design with three replicates. N levels (N 0, 80, 160 and 240 kg/ha) as urea were in the main plots (control = N 0 kg/ha), and maize cultivars (SC-301, DC-370 and SC-404) were allocated at random in the sub-plots. Results indicated that nitrogen levels had significant effects on yield and yield components in maize hybrids. Maize cultivars had different response to this characteristic. The highest grain yield was obtained from the highest levels of nitrogen fertilizer. The highest number of kernel per ear, the number of grains per ear row, ear diameter, cob length, grain per plant, plant height, the number of grains per ear row and number of kernels per ear were recorded at the highest levels of nitrogen fertilizer. The number of grain row and number of cobs per plant were not affected in maize cultivars by levels of nitrogen fertilizer. Effect of cultivar x nitrogen levels was significant on grain yield. Maximum grain yield (7.76 ton/ha) was obtained in the plots with N 240 kg ha(-1) and SC-404 cultivar and minimum of it (5.12 ton/ha) was obtained in the plots with 0 kg nitrogen ha(-1) and SC-301 cultivar. It can be suggested that SC-404 hybrid should be applied with N 240 kg/ha in conditions of Ardabil Plain.