Effect of nitrogen fertilizer rate on grain yield, phyllochron and leaf emergence rate in three maize cultivars

In order to investigate the effects of nitrogen levels on grain yield، phyllochron and leaf emergence rate of maize cultivars، a split plot experiment based on randomized complete block design with three replications was conducted at the Research Farm of Islamic Azad University of Ardabil during 2007 cropping. Factors were: nitrogen levels in main plots (0، 80، 160 and 240 Kg N ha-1) and maize cultivars in three levels (SC-301، DC-370 and SC-404) in sub plots. The results showed that phyllochron، time between the appearance of successive leaves on a shoot، was significantly affected by corn، nitrogen levels and interaction of nitrogen levels × maize cultivars. With increased nitrogen levels، the phyllochron was decreased but rate of leaf appearance was increased. Response of maize cultivars was different to these characteristics. Leaf appearance rate in SC-301 was more than SC-404 and DC-370. The highest leaf appearance rate and the least of time for phyllochron was obtained in treatment compounds of SC-301 with application of 240 kg N/ha. Grain yield was significantly as affected by nitrogen levels، cultivar and interaction of cultivar × nitrogen levels. Maximum grain yield was in SC-404 cultivar and minimum of it was in SC-301 cultivar. Means comparisons showed that maximum grain yield was obtained in SC-404 with application of 240 kg N/ ha. However، no significant different was between application of 160 and 240 kg n/ha. Minimum grain yield belonged to SC-301 without application of nitrogen fertilizer. If growth period was limited، it seems that SC-301 with 240 kg N/ha was applied in order to increasing leaf appearance rate and decreasing of phyllochron. However، if growth period wasn’t limited، it would be better to use of SC-404 with application of 240 kg N/ha.