| Abstrakt: |
Rice sheath blight caused by Rhizoctonia solani Kuhn has become an important constraint in rice cultivation in India and other tropical countries. The present study explores the effects of weather factors (temperature, relative humidity, rainfall and bright sunshine hours) on paddy sheath blight severity. During kharif 2020-21 at Zonal Agricultural Research Station, V.C. Farm, Mandya, all tested nine genotypes (Jyothi, Jaya, IR 64, Thanu, MTU 1001, MTU 1010, BR 2655, KRH4 and HR12) showed distinct responses to sheath blight disease. The disease started on the 28th November 2020 with a mean severity of 0.31 per cent, gradually increasing to a peak on 11th January 2021 (37.41%). The Jyothi (highly susceptible) genotype showed the highest mean disease severity (20.16%), whereas the BR 2655 which is moderately susceptible, showed the lowest mean sheath blight severity (10.90%). The optimal weather conditions for disease development were maximum temperature (25.50-29.62 °C), minimum temperature (16.50-18.50 °C), morning relative humidity (87.94-93.23%), evening relative humidity (53.74-75.54%), rainfall (2.00-20.50 mm) and sunshine (3.20-10.50 hours). Correlation analysis showed that the maximum air temperature was the key factor in governing the disease in the field among all the meteorological factors. A maximum temperature (25.50-29.62 °C) was found favor the development and spread of sheath blight after its establishment in the field. A predictive model was developed with a coefficient of determination (R²) of 0.804-0.848 using statistical language R. A step-wise multiple regression analysis approach was adopted to identify the most appropriate predictive variables to constitute the linear regression model. [ABSTRACT FROM AUTHOR] |
