Effect of different levels of nitrogen fertilizer on yield and yield component of some new maize cultivars (Zea mays L.) in Kermanshah

In order to evaluate the effect of different levels of nitrogen fertilizer application on yield and yield components of some maize cultivars, a split plot experiment was done based on randomized complete blocks design with four replications in the campus of agricultural and natural recourses farm, Razi University, at 2014. Treatments were four levels of nitrogen fertilizer application (40%, 70%, 100% and 140% of the maize demand to nitrogen which based on the amount recommended by soil testis equivalent to 138, 238, 350 and 483 kg.ha-1 urea) as main plots and three common maize cultivars SC 704, BC 678 and Simon as sub plots. The results indicated that nitrogen fertilizer improved number of ear per square meter (12%), number of row per ear (9%), number of grain per row (32%), grain yield (63%) and total dry weight (58%). Simon cultivar had more need to nitrogen fertilizer to achieve maximum yield. Simon cultivar had the most grain yield (19%) than other cultivars. Harvest index was higher for Simon cultivar in fertilizer level of 140% while harvest index for other cultivars reduced by increasing of nitrogen fertilizer application from 40% to 140% of plant demand. Simon cultivar (10467 kg.ha-1) in 140% fertilizer level and SC-704 (8402 kg.ha-1) and BC-678 (8030 kg.ha-1) in 100% fertilizer level had maximum grain yield. In general, our results showed that in the studied region to achieve higher yield, it is better new maize cultivars be cultivated such as Simon.