Effect of nitrogen fertilizer application rate and timing on yield and yield components of forage Corn (Zea mays L.) after Wheat harvesting in Ghaemshahr region

In order to study the effect of amount and time of nitrogen fertilizer application on yield and yield components of forage corn after wheat harvesting, an experiment was conducted as split plots Based on randomized complete block design with 4 replications at Qarakhail Ghaemshahr Agricultural Station Associated with Mazandaran Agricultural Research Center in the 2016-2017 crop year. Experimental factors included nitrogen fertilizer application time as main factor in three levels (5-leaf, 9-leaf and 9+5-leaf situation) and nitrogen fertilizer rates as the secondary factor in four treatment levels (0, 125, 250 and 375). The results showed that nitrogen application time did not affect any studied traits, but nitrogen rates had a significant effect on most of the studied traits. The lowest plant height (193.3 cm) and corn length (94.25 cm) were obtained in no nitrogen application, and other nitrogen application treatments were located in a same statistical group. Also, the highest number of grain rows per ear (14.33 and 14.58 rows, respectively) were obtained with 125 and 375 kg nitrogen per hectare, and the highest number of grains per ear row (34.83 and 35.25 grains, respectively) were obtained in 250 and 375 kg/ha nitrogen. Other results showed that the lowest amount of fresh and dry weight of forage corn were obtained in no nitrogen application, so that other levels of nitrogen content were located in same statistical group. Interaction effect experimented factors showed that the highest amount of grain number rows per ear (15.50 rows) was obtained with 375 kg /ha nitrogen applied at the 9-leaf stage.