Effect of canopy microclimate on sheath blight infestation and yield loss in irrigated rice.
2004
Tang, Q. | Zhong, X. | Peng, S. | Buresh, R.J.,International Rice Research Inst., DAPO Box 7777, Metro Manila (Philippines). Crop, Soil and Water Sciences Div.)
Disease development is affected by the pathogen source and the microclimate within the crop canopy. To determine the effect of sheath blight inoculation on rice yield and to analyze the relationship between sheath blight severity and the canopy microclimate factors, the authors conducted field experiments using treatments of N fertilizer application, plant spacing, and cultivars in the dry season (DS) and wet season (WS) of 2003 at the International Rice Research Institute [Los Banos, Laguna, Philippines]. The rice plant was inoculated with the pathogen Rhizoctonia solani and fungicides were not applied. The canopy microclimate factors were recorded with HOBO dataloggers and a SunScan Canopy Analysis System. Results showed that field inoculation with sheath blight pathogen induced disease development in all inoculated hills, and sheath blight severity index (ShBl) differed significantly in different treatments. Field inoculation with sheath blight pathogen caused an average yield loss of 21 percent in the DS and 10 percent in the WS. Yield loss had a positive relationship with ShBl; the relationship was significant in the DS and in the hybrid rices during the WS. In the DS, the canopy temperature and relative humidity (RH) were significantly affected by the treatments. Canopy temperature and RH had a significant effect on ShBl. In the WS, there were smaller differences in canopy temperature and RH across treatments compared with that during DS, and ShBl was mainly affected by the percentage of light penetration inside the canopy. These results suggest that a healthy canopy with a microclimate less conducive to disease development could be achieved through crop management and thereby increase grain yield and yield stability.
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