تأثیر میزان نیتروژن و زمان برش علوفه بر عملکرد علوفه و دانه جو کارون

Effects of different levels of nitrogen fertilizer and cutting time of forage on grain and forage yield of barley (Hordeum vulgare L.) Karoon cultivar was studied during 1995-1996 at Ramin Agricultural Research and Educational Center, University of Shahid Chamran, Ahwas, by using a split plot design in randomized complete block with 4 replications. Main plots were assigned to five levels of N fertilizer (45, 90, 135, 180 and 225 kg N/ha) as urea fertilizer and subplots to three cutting times (no cutting, cutting forage at early stem elongation without removing reproductive meristem and cutting forage in the middle of stem elongation with cut reproductive meristem). The effects of N rates and cutting time on grain yield were significant. Maximum yield was obtained with 281.6 g/m2 when crop plants received 90 kg N/ha and cutting time at early stem elongation and minimum yield was obtained (158.2 g/m2) with 45 kg N/ha and cutting forage in the middle of stem elongation. Interactive effect of levels of N and cutting time on spike number per m2, grain number in spike and grain weight were significant. Among yield components, spike number and grain weight showed the highest sensitivity to both. Different levels of N increased forage protein concentration and protein yield significantly, but delay in cutting time decreased protein concentration and increased protein yield. Results indicated that high levels of N could not compensate for the delay in cutting time of forage for grain yield. It was concluded that application of 90 kg N/ha and cutting time in early stem elongation was preferable for grain and forage production as compared to other treatments.