Effect of nitrogen stress at different plant growth stages and leaf colour chart based nitrogen application on the development of brown spot disease of rice

The nitrogen level of soil greatly influenced the development of brown spot (Drechslera oryzae) disease of rice. Field experiments conducted during kharif 2005 and 2006 revealed that the disease severity and grain yield were significantly influenced by different nitrogen levels. Disease severity increased with decreasing nitrogen levels from 180kg N/ha (25.87%) to 0kg N/ha (48.43%) under artificially inoculated conditions. Most critical stage for nitrogen application was 0 DAT followed by 21 DAT and 42 DAT. The application of total dose of nitrogen (120kg N/ha) as per standard three split method was found superior over application after splitting into two equal parts in reducing the disease severity as well as for getting higher grain yields. Nitrogen application as per leaf colour chart (LCC) method was better in reducing disease severity over standard three split method. Grain yields obtained by both the methods were at par with each other.