Path coefficient analysis on the effects of blast on rice growth, yield components and yield loss [Philippines]
1988
Torres, C.Q. | Teng, P.S. (International Rice Research Inst., Los Banos, Laguna (Philippines))
Two trials were conducted to determine the effects of blast on rice growth, yield components and yield loss. Epidemic was manipulated by covering some of the plots with plastic sheets at night, applying different amount of inoculum, timing of inoculation and spraying tricyclazole. Tillers were sampled weekly to measure leaf blast severity, plant height and biomass. At harvest panicle blast incidence was determined and yield components measured. Different epidemic patterns were obtained in both trials. Path coefficient analysis showed that leaf blast had relatively stonger negative effect on plant height than on the leaf, stem and panicle biomass. Panicle blast on the other hand had a stronger effect on panicle biomass than the leaf blast. Among the yield components, number of filled grain (NOFG) and 1,000 grain yield are the two almost equally affected by leaf blast. Percent unfilled grain (% UG) is more affected by panicle blast than by the leaf blast. Tha NOFG and %UG had the highest direct effect on yield loss in the first and second trial, respectively. Two equations that would predict yield loss (%) at any observed leaf blast severity (maximum) and panicle blast incidence were developed.
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