Post-harvest leaf abscission in Summer-grown basil (Ocimum basilicum L.) may be controlled by combining a pre-treatment with 1-MCP and moderately raised CO2

Abstract

SUMMARYThe regulatory effects of 2.5 kPa CO2 and the ethylene action inhibitor, 1-methylcyclopropene (1-MCP), at 0.7 µmol l−1, were assessed on accelerated senescence in post-harvest basil (Ocimum basilicum L.). Three indicators of quality deterioration: browning, leaf decay, and leaf abscission were evaluated visually and scored on indices linking the onset and progression of senescence to marketability. In control sprigs not exposed to ethylene, moderately raised levels of CO2 were found to reduce browning and decay. Pre-treatment with 1-MCP alone reduced browning, but not decay. Exogenous ethylene accelerated leaf browning and decay only slightly, but caused unacceptably high rates of leaf abscission. Pre-treatment with 1-MCP was found to be more effective than CO2 at inhibiting the enhancing effect of exogenous ethylene on leaf abscission. However, the combined treatment had a significant effect in completely preventing ethylene-induced leaf abscission. Exposure of basil sprigs to exogenous ethylene resulted in an increased production of endogenous ethylene, which increased greatly following pre-treatment with 1-MCP and, to a lesser extent, in CO2-treated sprigs.