Effects of Atmospheric Ozone on the Rice Blast Pathogen Pyricularia grisea

  • Hur, Jae-Seoun (Department of Environmental Education, Sunchon National University) ;
  • Kim, Ki-Woo (National Instrumentation Center for Environmental Nanagement, Seoul National University) ;
  • Kim, Pan-Gi (National Instrumentation Center for Environmental Nanagement, Seoul National University) ;
  • Yun, Sung-Chul (School of Applied Biology and Chemistry, Seoul National University) ;
  • Park, Eun-Woo (School of Applied Biology and Chemistry, Seoul National University)
  • Published : 2000.02.01

Abstract

The direct effects of acute $\textrm{O}_3$ on the growth, sporulation and infection of Pyricularia grisea, rece blast pathogen, were investigated to understand the interactions between ozone and the pathogen. Acute exposure of 200 nl $\textrm{l}^{-1}$ ozone for 8 h significantly reduced conidia germination on water atar. Ozone exposure of 200 nl $\textrm{l}^{-1}$ for 8h per day for 5 days had no effect on increase in colony diameter, but severely damaged actively growing aerial mycelia. However, the damage to mycalia was recovered during the following 16 h exposure of unpolluted air. Conidial production was also stimulated by the acute ozone exposure for 5 days. The conidia exposed to the acute ozone for 5 days normally germinates but slightly reduce appressoria formation on rice leaf. However, the conidia produced by artificial stimulation under the same ozone concentration for 10 days showed significant reduction in appressorea for mation on a hydrophobic film. This study suggests that the acute ozone could ingibit appressoria formation as well as vegetative growth of the pathogen, resulting in decrease in rece blast development in the field during summer when high ozone episodes could occur occasionally.

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