Articles
THE INFLUENCE OF A SURFACE COATING ON THE INTERNAL GAS ATMOSPHERE AND RATE OF POSTHARVEST ROT DEVELOPMENT IN CONFERENCE PEARS
Article number
518_9
Pages
79 – 86
Language
Abstract
Observations of ‘Conference’ pears (Pyrus communis L.) held at 20°C indicate that within 2 hours of application of a 1.5% preparation of the sucrose-ester coating, ‘TAL Pro-long’, the internal gas atmosphere of the fruit was significantly modified.
The oxygen (O2) concentration fell from approximately 14% to less than 2% and, over a period of 18 hours, carbon dioxide (CO2) levels rose from 6% to a peak value between 20 and 24% and ethylene levels declined from 100ml litre-1 at the time of coating to 20ml litre-1 when the observations ceased.
In pears artificially inoculated with the fungal pathogen Monilinia fructigena Pers. (Black or Brown Rot) prior to coating, the transformation of the internal concentrations of O2 and CO2 were followed by distinct changes in the rate of lesion expansion.
Some 32 hours after treatment and approximately 14 hours after the level of CO2 had reached a maximum, significantly lower rates of lesion expansion were observed on coated fruit as opposed to the controls.
These results together with observations of a range of other pathogenic cultures held ‘in vitro’ in modified air and a gas atmosphere enriched with CO2 suggest that the ability of the TAL Pro-long treatments to retard the rate of spread of M. fructigena results from a physiological response of the host to the gas environments engendered by the coating and not a direct consequence of elevated CO2 and depressed O2 concentrations of the metabolism of the fungus.
The oxygen (O2) concentration fell from approximately 14% to less than 2% and, over a period of 18 hours, carbon dioxide (CO2) levels rose from 6% to a peak value between 20 and 24% and ethylene levels declined from 100ml litre-1 at the time of coating to 20ml litre-1 when the observations ceased.
In pears artificially inoculated with the fungal pathogen Monilinia fructigena Pers. (Black or Brown Rot) prior to coating, the transformation of the internal concentrations of O2 and CO2 were followed by distinct changes in the rate of lesion expansion.
Some 32 hours after treatment and approximately 14 hours after the level of CO2 had reached a maximum, significantly lower rates of lesion expansion were observed on coated fruit as opposed to the controls.
These results together with observations of a range of other pathogenic cultures held ‘in vitro’ in modified air and a gas atmosphere enriched with CO2 suggest that the ability of the TAL Pro-long treatments to retard the rate of spread of M. fructigena results from a physiological response of the host to the gas environments engendered by the coating and not a direct consequence of elevated CO2 and depressed O2 concentrations of the metabolism of the fungus.
Authors
R.D. Bancroft
Keywords
Cylindrocarpon mali, in vitro gas, Penicillium expansum, Alternaria alternata, Botrytis cinerea, Geosporium perennans, Monilinia fructigena, Pyrus communis, Carbon Dioxide, Coating, Conference pear, Ethylene, Fungi, Gas atmosphere, lesion expansion, Lesion, Monilinia cinerea, Oxygen, Pathogen, postharvest, reduced spread., Rot, Sucrose-ester, TAL Pro-long
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