The effect of 1-methylcyclopropene (1-MCP) at three different doses (0.25, 0.50, and 0.75 muL L-1) on the ripening processes of a climacteric, cv. Santa Rosa, and a suppressed climacteric type, cv. Golden Japan, plum was studied. For both cultivars, positive effects were observed in terms of inhibition of ethylene production and delays of the physical, chemical, and biochemical changes associated with ripening. 1-MCP-treated plums were firmer with lower weight loss, reduced degreesBrix/titratable acidity ratios, and lower color changes during cold storage and subsequent shelf life at 20 degreesC than controls. For most factors, the effectiveness of 1-MCP was dose-dependent in Santa Rosa but dose-independent for Golden Japan.