Influence of nitrogen on guttation fluid and development of bacterial blight of rice

Bacterial blight disease of rice is major constraint in rice cultivation. This disease is influenced by prevailing weather conditions, rice physiology and nutrition. The experiment was carried out to assess the role of nitrogenous fertilizer on development of bacterial blight disease of rice and Xanthomonas oryzae pv. oryzae density in guttation fluid. Disease development increased with increase in nitrogen fertilizer, among four doses of nitrogen tested (control, 36, 54,72 kg urea/acre), disease severity was maximum in the plot supplied with highest dose of nitrogen i.e. 72 kg urea/acre at both seedling (19.3%) and tillering stage (32.4%) at 30 days after inoculation. The highest population density of X. oryzae pv. oryzae (6.02 log cfu/ml) was also recovered in guttation fluid collected from X.oryzaepv. oryzae inoculated plants at tillering stage, from the plots supplied with highest dose (72 kg urea/acre) of nitrogen.Scanning electron microscopic studies also revealed intense colonization by X. oryzae pv. oryzae in rice leaves supplied with high nitrogen dose