Carbon dioxide and 1-MCP inhibit ethylene production and respiration of pear fruit by different mechanisms

Ethylene production in relation to O-2 partial pressure of whole pear fruit stored at 2 degrees C could be described by a Michaelis-Menten equation. This was indicated by the use of a gas exchange model. The maximum ethylene production rate was strongly inhibited while the K-mO2 value (1.25 kPa) was not affected by elevated CO2. Ethylene production was also inhibited by 1-MCP, an inhibitor of ethylene perception. The reduction in ethylene production by CO2 was similar for 1-MCP treated and untreated pears. Elevated CO2, therefore, must have had an influence on ethylene production other than through ethylene perception. A possible site of inhibition by CO2 is the conversion of ACC to ethylene. The O-2 uptake rate in relation to O-2 partial pressure of whole pear fruit could be described by a Michaelis-Menten equation. The O-2 uptake rate was inhibited by elevated CO2 at a level similar to the inhibition of ethylene production. Again the K-mO2 value (0.68 kPa) was not affected by CO2. Using 1-MCP treatments it was shown that there was no direct effect of inhibited ethylene production on O-2 uptake rate.