Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 24, 2007
Publication Date: December 1, 2007
Citation: Argenta, L.C., Fan, X., Mattheis, J.P. 2007. Responses of 'golden delicious' apples to 1-mcp applied in air or water. HortScience. 42:1651-1655. Interpretive Summary: Apple ripening occurs as fruit tissue senses the presence of ethylene, a gas produced by the fruit itself. The capacity to sense ethylene resides in a small number of proteins to which another compound, 1-methylcyclopropene or 1-MCP, also binds. When 1-MCP is stuck to these proteins, the presence of ethylene is sensed and ripening occurs at a greatly decreased rate. The process of ‘Golden Delicious’ apple fruit ripening includes a number of changes that result in fruit becoming softer, sweeter with a yellowing of the peel. In fruit where 1-MCP is present, these processes occur slower. These fruit may also develop a grayish discoloration on the peel itself, which can reduce the appearance quality of the fruit but does not impact edible quality.
Technical Abstract: ‘Golden Delicious’ [Malus sylvestris var. domestica (Borkh.) Mansf.] apple fruit were treated with 1-methylcyclopropene (1-MCP) at 0.42, 4.2 or 42 umol m**-3 in air at 20 deg C or 0.03, 0.3 or 3 mmol m**-3 in 20 deg C water. Fruit were held in air at 20 deg C for 25 days after treatment or stored at 0.5 deg C in air or in a controlled atmosphere (CA: 1.5 kPa 02 + 2 kPa CO2) for up to 6 months followed by 7 days in air at 20 deg C. Application of 1-MCP in air or water delayed the climacteric increase in respiration and ethylene production, and reduced softening, loss of acidity and peel color changes. Treatments applied as a water dip required a concentration 700 fold higher compared to gas treatment to induce similar physiological responses. Fruit responses to 1-MCP varied with treatment concentration with the maximum effects obtained at concentrations of 4.2 and 42 umol m**-3 in air and 3 mmol m**-3 in water. 1-MCP treatment followed by storage in air was as effective as CA storage for retention of firmness and titratable acidity during 6 months storage. Simultaneous ethylene (55 mmol m**-3) and 1-MCP (42 umol m**-3) treatment did not overcome 1-MCP effects on the inhibition of fruit ripening during holding at 20 deg C. Peel color changes were impacted less than retention of firmness and titratable acidity for some 1-MCP treatments. 1-MCP treatment was less effective for slowing peel degreening when treated fruit were stored at 0.5 deg C. In one season, fruit treated with 1-MCP and stored in air at 0.5 deg C developed a peel disorder typified by a gray-brown discoloration that is unlike other disorders previously reported for this cultivar. Symptoms were observed the day fruit were removed from cold storage and no change in symptom appearance was observed during 7 days at 20 deg C.