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- Epidemiology of rice blast and productivity of rice-corn intercropping...
Epidemiology of rice blast and productivity of rice-corn intercropping system in Sulawesi, Indonesia
Dissertation Abstract:
Rice blast, caused by Magnaporthe oryzae, is one of the most devastating rice diseases worldwide. Intercropping supports sustainable rice farming practices by promoting biodiversity and potentially inhibiting the spread of plant diseases. This study aimed to assess the effect of rice-corn intercropping on leaf and panicle blast progress, determine yield losses due to leaf and panicle blast, and compare the growth, yield, and productivity of rice and corn under various intercropping treatments. The field experiment was conducted in the 2022 wet and dry seasons in the rice blast-prone area of Southeast Sulawesi, Indonesia, using a Split plot design with three replications. The main plot consisted of treatments with and without fungicide application. The subplots were 40% rice + 60% corn and 60% rice + 40% corn intercropping and pure rice and corn stands. Leaf and panicle blast severities were assessed at different growth stages during the cropping season. Morphological and yield attributes were measured for rice and corn. This study showed that the 40% rice + 60% corn intercropping reduced leaf and panicle blast severities and area under disease progress curve (AUDPC) in the wet season. In the dry season, intercropping with 40% rice + 60% corn and 60% rice + 40% corn reduced leaf blast severity and AUDPC but did not reduce panicle blast severity and AUDPC. Seasonal variation in rice blast infection was observed, with higher leaf blast severity and AUDPC in the dry season than in the wet season, while panicle blast severity and AUDPC were higher in the wet season than in the dry season. Grain yield was higher in 40% rice + 60% corn intercropping due to lower leaf and panicle blast severities and yield loss compared to 60% rice + 40% corn intercropping and pure rice stand in the wet season. In the dry season, grain yield was higher in 60% rice + 40% corn intercropping than in 40% rice + 60% corn intercropping. Intercropping with 40% rice and 60% corn is suitable in the wet season because it had a 14% yield advantage, a competitive ratio <1, and a positive actual yield loss index. The 60% rice + 40% corn intercropping is suitable in the dry season because it had a 15% yield advantage and positive actual yield loss.