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United States Department of Agriculture

Agricultural Research Service

Research Project: MAINTAINING QUALITY AND EXTENDING SHELF AND SHIPPING LIFE OF FRESH FRUIT WITH NO OR MINIMAL SYNTHETIC PESTICIDE INPUTS

Location: Commodity Protection and Quality

Title: Germination of fungal conidia after exposure to low concentration ozone atmospheres.

Authors
item Rubio Ames, Zilifina -
item Feliziani, Erica -
item Smilanick, Joseph

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 1, 2013
Publication Date: July 1, 2013
Citation: Rubio Ames, Z., Feliziani, E., Smilanick, J.L. 2013. Germination of fungal conidia after exposure to low concentration ozone atmospheres. Postharvest Biology and Technology. 83:22-26.

Interpretive Summary: Fungi cause many kinds of fresh produce to rot after harvest unless actions are taken to control this problem. Ozone gas kills fungi, but the concentrations needed to accomplish this under the cold storage conditions used for many fresh products was not known. We determined the mortality of six common fungal species in an ozone atmosphere and these values can be used to facilitate the effective use of this gas to protect products after harvest.

Technical Abstract: The germinability of conidia of Alternaria alternata, Aspergillus flavus, Aspergillus niger, Penicillium digitatum, Penicillium expansum, or Penicillium italicum was determined periodically during exposure for approximately 100 days to a humid atmosphere of air alone or air containing 150 ppb ozone at 2 °C. Conidia were exposed to ozone on glass coverslips that were removed from the ozone chamber at intervals of one week and the germination of 100 conidia of each species was assessed after incubation for 24 h on potato dextrose agar. The period in days when 50% or 95% (ET50 and ET95, respectively) could not germinate and 95% confidence intervals for these estimates were made using Finney’s probit analysis. ET50 and ET95 estimates were approximately one month and two to three months, respectively. Some natural mortality of the conidia occurred during these periods, so the entire decline in germinability was not solely due to ozone. The age of the culture from which conidia were collected influenced their susceptibility to ozone. Conidia were harvested from 7, 14, 21, and 28 day old potato dextrose agar cultures of P. digitatum and exposed to ozone 13 mL-L-1 at 2 °C. After 48 hours of exposure to ozone, none of the conidia from the seven day old culture germinated, while 30 to 35% of the conidia from the 14, 21, or 28 day old cultures germinated.

Last Modified: 4/24/2014
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