Effect of deficit irrigation and nitrogen fertilizer on quantitative yield of aboveground part of forage pear millet (Pennisetum glaucum) in Birjand

Water shortage is the most important limiting factor for achieving potential yield of crops, especially in arid and semiarid regions. Nitrogen is also amongst the most important factors that limit agricultural production. In order to study the effects of deficit irrigation and fertilizer on forage yield as well as aboveground dry and fresh weight of forage millet (Notrifid), a split plot experiment based on randomized complete block design was conducted with three replications in the Research Field of the Islamic Azad University of Birjand in 2006. Irrigation levels (50 and 100 percent of the plant required water) and nitrogen fertilizer levels (0, 75, 150 and 225 kg N ha-1), were considered as the main and sub plots, respectively. Analysis of variance showed that both irrigation and nitrogen had a significant effect on dry and fresh weight of leaves and stems as well as forage yield of millet in the sum of the two harvesting stages. The interaction of experimental treatments, however, was not significant in any of these traits. By reducing irrigation, the sum of forage yield decreased from 40.72 to 24.92 t ha-1 and the hay yield also decreased from 8.94 to 5.34 t ha-1. Increasing nitrogen usage up to 225 kg N ha-1 enhanced the total fresh and dry yield for about 79.8 and 81.2%, respectively, compared to the control treatment (0 nitrogen). In general it can be concluded that irrigation and nitrogen are the two effective factors determining the forage yield of millet.