Interactions between 1-MCP concentration, treatment interval and storage time for 'Bartlett' pears

Storage trials were carried out over two seasons to determine a suitable treatment protocol for the use 1-methylcyclopropene (1-MCP) with 'Bartlett' (Williams) pears. In the 2000 season, pears were exposed to 0, 0.01, 0.1, 0.5 or 1.0 mul l(-1) 1-MCP at 0degreesC, then stored at -1 degreesC for up to 24 weeks before ripening at 20 degreesC. The effects of the lower concentrations dissipated after a time, allowing fruit to reach eating ripeness. Superficial scald development was delayed, but not prevented, in these fruit. Although 1.0 mul l(-1) effectively prevented scald, these fruit failed to soften. Overall, concentrations of 0.1-0.5 mul l(-1) 1-MCP appeared to have the most potential as storage treatments. In the 2001 season, fruit were exposed to 0, 0.2 or 0.4 mul l(-1) 1-MCP at 0degreesC. After 4 or 6 weeks at -1 degreesC, half the fruit were re-treated at 0 degreesC and stored at -1 degreesC for a further 4 or 6 weeks. Re-treatment after 4 weeks had a greater effect on color development and softening after storage than did the initial 1-MCP application. In contrast, fruit re-treated after 6 weeks showed little response to the additional 1-MCP exposure. These results suggest that green fruit recover ethylene sensitivity more slowly when re-treated with 1-MCP after a period of storage. However, if fruit have started to ripen they are relatively insensitive to additional 1-MCP. Treatment with 1-MCP reduced fruit sensitivity to handling damage, even after ripening. The results are discussed in terms of the practical difficulties with application of 1-MCP to 'Bartlett' pears as well as potential commercial benefits. (C) 2003 Elsevier B.V. All rights reserved.