Influence of Nitrogen Levels and Application Methods on Yield and Quality of Sorghum

A field study was conducted for two years at the Arid Zone Research Institute,Dera Ismail Khan,Pakistan,to determine the optimum level of nitrogen and efficient application method in the production of sorghum(Sorghum bicolor L.).Using four levels of nitrogen,i.e.,0,60,90,and 120kg ha-1,and two different application methods(soil application and foliar spray),the experiment was laid out in a split-plot design,where the main plots were used to determine the effective method of application and the subplots were used to detect the influence of N levels on the grain yield.The average data obtained after two years of study indicated an increase in the grain yields with an increase in N levels irrespective of the method used of N application.The grain yield increased from 2.92 to 5.61 t ha-1in the plots that were treated with 90 kg N ha-1compared with the control plots.Quadratic regression analysis showed that the increase in the yield was higher at the lower levels of N compared with the succeeding higher levels.The soil application method, producing an average grain yield of 4.79 t ha-1,was found to be superior to the foliar spray method with an average grain yield of 4.56 t ha-1.The protein content of the grain showed a linear increase with N application,attaining the maximum at 120 kg N ha-1in both the methods of N application.In addition,compared with the method of soil application,higher crude protein contents were observed using the method of foliar spray at all N levels.