Comparison of hydrogen sulphide with 1-methylcyclopropene (1-MCP) to inhibit senescence of the leafy vegetable, pak choy

Postharvest fumigation with hydrogen sulphide (H2S) can inhibit senescence of a range of fruit and vegetables. It has been suggested that the mode of action of hydrogen sulphide is through inhibiting either the endogenous production and/or the action of ethylene. This study compared the effect of fumigation with 250 mu L L-1 hydrogen sulphide and 10 mu L L-1 1-methylcyclopropene (1-MCP) on a range of factors associated with senesence of the leafy vegetable, pak choy stored at 10 degrees C and ventilated with ethylene-free air or air containing 0.1 mu L L-1 ethylene. When pak choy was stored in an ethylene-free atmosphere, hydrogen sulphide and 1-MCP were equally effective in inhibiting the loss of green colour, respiration, ion leakage and endogenous ethylene production. However, for containers ventilated with ethylene, 1-MCP was more effective in inhibiting loss of green colour, respiration and ethylene production than hydrogen sulphide. Sequential fumigation with 1-MCP followed by hydrogen sulphide showed no difference in any quality factor to produce fumigated with 1-MCP. The study concluded that (i) the mode of action of hydrogen sulphide included inhibiting the action of ethylene and (ii) for pak choy, 1-MCP was a more effective fumigation treatment than hydrogen sulphide.