Effect of light, temperature, and water potential on growth and sporulation of Microdochium oryzae uri icon

abstract

  • Radial growth or conidial production of Microdochium oryzae, the causal pathogen of rice (Oryza sativa) leaf scald, was higher on potato-sucrose-salt agar (PSSA) than malt extract agar, nutrient agar, potato-dextrose agar, potato-sucrose agar (PSA) or V8 juice agar. Radial growth on PSSA was 8.5 mm/d with production of 3 X 10(6) conidia/cm(2) d at 21 C. The fungus grew appressed producing innumerable raised salmon-colored sporodochia. The sporodochia were cream colored on the reverse side of the PSA and PSSA plates. Radial growth or conidial production was greater in the dark at 25 or 30 C, than under 12-h cycle of light and dark at 21 C. The fungus grew faster when the water potential (psi) was adjusted to -0.14 to -1.0 MPa with sucrose or KCl than with NaCl. The radial growth in sucrose-, KCl- or NaCl-amended media increased as psi(s) decreased from -0.14 to -0.53 MPa and with increased incubation from 15 to 30 C; and declined with decreased psi(s) from -4.83 to -5.3 MPa in sucrose and -8.23 to -8.81 MPa in KCl or NaCl. Conidial production on psi(s) -0.14 to -2.07 MPa in sucrose was two-fold higher than in KCl and four-fold higher than in NaCl. Conidial production increased steadily with decreased psi(s) from -1.0 to -1.2 MPa at 25 or 30 C in sucrose, however, decreased at psi(s) from -0.25 to -0.7 MPa and then increased at -1.8 MPa in KCl or NaCl.

publication date

  • 1998
  • 1998