The effect of 1-methylcyclopropene (1-MCP) on the physical and biochemical characteristics of onion cv. SS1 bulbs during storage

There is a paucity of information on the role of ethylene in onion bulb dormancy, and the available literature is conflicting. Onion cv. SS1 bulbs were treated with 1 mu l(-1) 1-MCP for 24h at 20 degrees C and then stored at 4, 12 or 20 degrees C. Sprout growth was reduced in onions treated with 1-MCP and stored at 4 or 12 degrees C, but not when stored at 20 degrees C. Greater concentrations of sucrose, glucose and fructose were measured in 1-MCP treated bulbs stored at 12 degrees C as compared with untreated bulbs. Dry weight was also maintained in onions treated with 1-MCP. Abscisic acid (ABA) concentration before storage has previously been shown to be correlated with storage life, but there were no differences in the ABA concentration between 1-MCP treated and untreated bulbs. It appeared that 1-MCP reduced the rate of carbon utilisation. The mechanism by which this occurred is unknown although it is unlikely to be mediated by ABA. (c) 2006 Elsevier B.V. All rights reserved.