The effect of different levels of nitrogen fertilizer on yield and fertilizer use efficiency of grain corn for different planting dates in Ardabil climate condition

Since cultivation of hybrid corn is rarely possible in Ardabil region, determining the best planting date for achieving optimum performance is the first step for its cultivation. Nitrogen as the most widely used nutrient required by plants, can affect performance. Therefore, in this study, the effect of different planting dates and different amounts of nitrogen on yield, yield components and nitrogen use efficiency in corn have been investigated.
A split plot experiment was carried out at the research station of University of Mohaghegh Ardabili with four replications based on randomized complete block design in order to study the effect of different levels of nitrogen fertilizers at different planting dates on yield and fertilizer use efficiency in corn at Ardabil climate. Main plots were three planting dates (10, 20 May and 30 June) and subplots were different nitrogen levels (0, 75, 150, 225 Kg N ha-1).
Interaction between planting dates and nitrogen levels was significant on grain yield, and the highest yield (12.33 t ha-1) was achieved in the first planting date (10 May) with 150 Kg ha-1 nitrogen level. The highest 1000-kernel weight (226 g) achieved in 10 and 20 May planting dates with 225 Kg ha-1 nitrogen and the highest biological yield (38.4 t ha-1) was related to 225 Kg ha-1 nitrogen level in second planting date (20 May). Fertilizer use efficiency was significantly affected by nitrogen levels and interaction between planting date and nitrogen levels, while planting date had no significant effect on fertilizer use efficiency. Comparison of means indicated that the highest value for fertilizer use efficiency (36.5 Kg Kg-1) was related to 75 Kg ha-1 nitrogen level in third planting date (30 June). The highest kernel no per ear (436) obtained in the third planting date (30 June) with application of 225 Kg ha-1 N. Also, the highest total kernel weight in ear (89.6 g) achieved in the first planting date (10 May) and application of 225 Kg ha-1 N.
In order to avhieve the highest grain yield (12330 Kg ha-1) in Ardabil climate it is recommended to plant corn on 10 May with application of 150 Kg ha-1 nitrogen.