The gaseous compound 1-methylcyclopropene (1-MCP) is becoming an invaluable tool to abate undesirable ethylene effects in horticultural commodities. In particular, ethylene-related postharvest physiological effects in climacteric fruit, leaf and flower abscission in floricultural commodities, and, in some instances, fruit decay have been reduced by postharvest 1-MCP application. 1-MCP is odorless, colorless, effective at low concentrations, and persistent in its effects in many crops (Blankenship and Dole, 2003; Watkins, 2006). The discovery of compounds such as 1-MCP that block ethylene binding to membrane-bound ethylene receptors have changed the way agricultural commodities are handled (Sisler, 2006).
Although horticultural commodities have benefited from postharvest use of 1-MCP, the potential for commodity improvements with preharvest applications of this plant growth regulator are only now being addressed. Progress in this area has been limited by the difficulty in successfully applying gaseous 1-MCP to plants in the field. Commodities that may benefit most from preharvest 1-MCP applications are those negatively impacted by ethylene exposure but do not have the desired response to compounds that inhibit ethylene biosynthesis. In these cases, ethylene may originate from neighboring plants, organs, or tissues or from application of exogenous compounds that generate ethylene such as ethephon (Warner and Leopold, 1969). This review focuses on minimizing unwanted phytotoxicity using 1-MCP when ethephon is used to cause loosening in mature citrus fruit.
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