Roushan Jafari; Raouf Seyed sharif; Ali Akbar Imani
Abstract
In order to study the influence of nitrogen and different harvesting dates on sorghum yield, a split plot experiment based on randomized complete block design was conducted with three replications in 2010 at the Research Farm of Islamic Azad University, Ardabil branch. Factors were: different harvesting ...
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In order to study the influence of nitrogen and different harvesting dates on sorghum yield, a split plot experiment based on randomized complete block design was conducted with three replications in 2010 at the Research Farm of Islamic Azad University, Ardabil branch. Factors were: different harvesting dates in three levels containing, beginning of flowering, two and four weeks after beginning of flowering and nitrogen fertilizer in four levels (zero, 60, 120 and 180 kg N.ha-1). The results showed that maximum of forage yield was obtained by the plots which were applied 180 kg N.ha-1 in four weeks after beginning flowering and the least of it was in no application of nitrogen fertilizer in beginning of flowering. Means comparison showed that the highest nitrogen use efficiency was obtained by the plots which was applied 60 kg N.ha-1 in four weeks after beginning flowering and the least of it was in application of 180 kg N.ha-1 × beginninig of flowering. Maximum of stem and leaf protein was obtained in the highest of nitrogen fertilizer rates. It seems that in order to increasing of forage yield, should be applied 180 kg N.ha-1 × four weeks after beginning flowering in climate conditions of Ardabil. If the aim is to improve nitrogen use efficiency, then applying 60 kg N.ha-1 in four weeks after beginning flowering can be suggested.