Study on Application Time and the Source of Nitrogen on Some Quantitative Characteristics of Two Grain Corn Cultivars

In order to study the effects of time-consuming and type of nitrogen fertilizer (urea and ammonium sulfate) on some quantitative characteristics of two varieties grain corn. The experiment was conducted factorial based on randomized complete block designed with 4 replications in Qazvin area. In this experiment, factor a (varieties) contains: 1- KSC 704 hybrid and hybrid KTC647 and factor B (nitrogen fertilizer) were 7 levels. The result showed that effects of variety and nitrogen fertilizer were significant.( 1% level) on grain yield. Grain yield of KSC 704 in all levels of factor B was higher than KTC 647, that because of high index of leaf area index (LAI), crop growth rate (CGR) and also longer growth period growth of KSC 704 than KTC 647. In nitrogen fertilizer treatments, treatments B6 and B4 (with yield 11315/8 and 10999 kg.ha-1) produced greatest grain yield because of more physiological indices of high leaf area index. Application of nitrogen fertilizer in two stages that is 25 and 55 days after planting (respectively 6-7 Leaves and 11-12 Leaves) has increased nitrogen use efficiency (NUE) in both varieties.