Effects of rates and nitrogen application timing on yield, agronomic characterstics and nitrogen use efficiency in corn

ABSTRACT: In order to study effects of rates and nitrogen application timing on yield, agronomic characteristics and nitrogen use efficiency in corn, an experiment was conducted as split plot based on randomized complete block design with three replications at the Research Farm of University of Mohaghegh Ardabili during 2009 cropping season. Nitrogen rates were arranged in main plot with four levels including: 0, 75, 150 and 225 Kg N.ha-1 and nitrogen application timing in sub plots by three levels including: (1/3 in planting + 1/3 in 8-10 leaf stages + 1/3 in tasseling initation ), ( ½ planting + ½ in tasseling initiation) and (½ in planting + ¼ in 8-10 leaf stages + ¼ in tasseling initation) as T1, T2 and T3 respectively. Results indicated that qualitative and quantitative yield, agronomic characterstics and nitrogen use efficiency were significantly affected by rates, N application timing and interaction of rates × N application timing. The highest the number of grain per ear, the number of grains per ear row and grain yield at the highest rates of nitrogen fertilizer with N application timing as T1. The number of grain row did not affected by rates of nitrogen fertilizer and N application timing. The highest grain yield (7928.6 Kg.ha-1) belonged to treatment combination of 225 Kg N.ha-1 with N application timing as T1. The effect of treatment combination of rates ×N application timing was significant on fertilizer use efficiency. Maximum nitrogen use efficiency (38.16 kg/kg) was obtained in treatment compounds which 75 Kg N.ha-1 as T1 was applied and minimum of it (19.41 kg/kg) was obtained in the treatment compounds which 225 Kg N.ha-1 as T2 was applied. Thus, it is suggested that in order to increasing of qualitative and quantitative yield and some agronomic characterstics such as plant height, cob length and diameter should be applied 225 Kg N.ha-1 as T1. But for increasing of nitrogen use efficiency can be suggested that 75 Kg N.ha-1 as T1 should be applied in conditions of experiment.