The Effects of 1-Methylcyclopropene on Botrytis cinerea infection of Petunia x hybrida Flowers in the Post Harvest Environment

Botrytis cinerearapidly infects petunia flowers in the postharvest environment. Previous research suggests that pollination is the initial event that causes the rapid flower decay. Self-pollination occurs on petunia when flowers are shaken in the post harvest environment during handling and transport to market. This suggests petunias treated with the ethylene-action inhibitor, 1-methylcyclopropene (1-MCP) prior to shipping can reduce the phenomenon known as flower petal meltdown. An experiment was conducted to determine the effect of 1-MCP on petunia flower senescence. The 2x2 factorial experiment consisted of petunia flowers that were hand-pollinated, or not pollinated, and then treated with 1-MCP or left untreated, for 24 hr. The flowers were then placed in a chamber with 99% humidity and inoculated with a conidial suspension of botrytis. Disease incidence data were collected at twelve-hour intervals for 72 h. Flowers were scored using a 1 to 9 scale based on disease progression, 1 having minimal necrosis and 9 being complete loss of tissue integrity. The non-inoculated control (no pollination and no 1-MCP treatment) had the lowest disease severity of 1.9 at 48 h, while the inoculated, pollinated, no 1-MCP treatment had the highest disease severity rating of 7.2. The 1-MCP treatment of pollinated flowers had a significantly lower disease severity rating (3.6) than the non 1-MCP-treated plants. Non-pollinated flowers, with or without 1-MCP, were not significantly different from pollinated flowers treated with 1-MCP. These results suggest than the phenomenon of petunia flower meltdown in the postharvest environment is initially caused by pollination, and 1-MCP is effective at reducing the rate of flower senescence. Also, botrytis infection of the flower petals results in a further increase in the rate of flower senescence regardless of pollination and 1-MCP treatments.