Effect of microclimatic modification and weather on brown leaf spot of rice

The field experiments were conducted during three kharif seasons 2012, 2013 and 2014 to study the effect of different planting methods and plant population on severity of rice brown leaf spot (Bipolaris oryzae) disease. The experiment was laid out in split-split plot design with date of transplanting in main plot, three planting methods (conventional, system of rice intensification (SRI) and furrow) in sub plot and two plant population (P₁-625 plants/plot and P₂-300 plants/plot) in sub-sub plot with four replications. The disease severity (percentage) was higher under conventional planting (44.7%) followed by SRI (39.2%) and furrow planting (33.8%). The disease severity percentage was higher (42.6%) in P₁ plant population as compared to P₂ plant population (36.8%). Total, mean and relative area under disease progress curve (AUDPC) was more in P₁ plant population under different planting methods (Bed, SRI and Conventional) as compared to P₂ plant population. The regression model was developed for 2012 and 2013 data with meteorological parameters and validated by using disease severity data of 2014. The relationship developed between observed and predicted values gave significant R² value (0.896).