Agronomical responses of sweet sorghum (Sorghum bicolor Moench) to plant density, irrigation interval and urea fertilizer treatment

The present field study was carried out under the climatic conditions of Hamedan, Iran. It was a split-split-plot experiment based on a Randomized Complete Block Design with four replications. The experimental treatments included plant density of sweet sorghum cv. Pegah at three levels of 100 000, 200 000 and 400 000 plants ha-2, irrigation interval of 10 and 15 days and urea fertilization pattern at two levels of 100, 200 and 100 kg ha-1 urea fertilizer (46%) at sowing date and 45 and 65 days after sowing (N1) and the application of 100, 100 and 200 kg ha-1 urea fertilizer at sowing date and 45 and 65 days after sowing (N2). The studied traits included shoot dry weight, fresh forage yield and dry forage yield. It was found that urea fertilization pattern significantly affected fresh weight, dry weight, fresh forage yield and dry forage yield. Plant dry weight and fresh and dry forage yield were influenced by the interactions between treatments. The highest fresh forage yield (81.20 t ha-1) was obtained at the density of 400 000 plants ha-2 with the irrigation interval of 10 days and urea application pattern of N2.