Study on the Effect of Different Urea Fertilizer Rates and Plant Populations on the Severity of Bacterial Blight (BB) of Rice

Abstract

To study the effect of different urea fertilizer rates and plant populations on disease severity of bacterial blight of rice and yield lasses related to disease, the experiments including three plant populations (110000, 150000, 190000) and five urea fertilizer rates (0,56 lb, 112 lb, 168 lb and 224 lb per acre) were conducted at Central Agriculture Research Institute farm in 1999 and 2000 rainy seasons. Manawthukha was used as a test variety that is susceptible to bacterial blight of rice. The disease severity could be increased by the application of urea. Although urea 112 lb per acre gave moderate disease severity than without urea, its yield is highest. The higher disease severity also showed the related effect of plant population of 150000 and above. However the combination of urea 224 lb per acre with the population of 190000 and 150000 gave the highest severity of bacterial blight disease and the minimum grain yield. The application of urea 224 lbs per acre can cause yield reduction ranging from 18.67 percent to 27.57 percent over the application of urea 112 lb per acre.