Effect of nitrogen on growth and yield of sorghum forage (Sorghum bicolor ( L.) Moench cv.) under three cuttings system

Abstract

A field experiment was conducted on sorghum (Sorghum bicolor (L.) Moench cv.) under three cutting system to determine the effect of nitrogen on growth and yield at University of Agriculture Faisalabad, Pakistan, during the season 2010-2011. The experiment was laid out in Randomized Complete Block Design (RCBD), using three replications. There were four levels of nitrogen 0, 50, 75 and 100 kg N/acre in the form of urea. The growth parameters like plant height, number of leaves, leaf area is determined periodically. First reading taken after 20 days of sowing while second and third was taken after 15 days of first cutting. Yield parameter like plant population, fresh and dry weight was determined in three cuttings. Results showed that increasing nitrogen dose increased all growth attributes. Results revealed for first, second and third cuttings showed significant differences at all growth attributes. Thus, the maximum plant height was observed in N4 (100 kg N/acre), having plant height 193.92, 195.24 and 192.79 cm in first, second and third cutting, respectively, which was followed by the treatment N3 (75 kg N/acre), having 179.70 cm in first cutting, while second and third cutting have same plant height 168.62 cm. The exception was the plant population showed non significant behavior in second and third cutting while number of leaves per plant in second cutting only and protein % in third cutting showed non significant difference with nitrogen application.