EFFECT OF 1-MCP ON THE POSTHARVEST PERFORMANCE OF UN-ROOTED POINSETTIA CUTTINGS

Abstract

Un-rooted poinsettia (Euphorbia pulcherrima 'Eckespoint Freedom Red') cuttings were placed into plastic bags at 10, 18 or 26°C for 72 h. 1-methylcyclopropene (1-MCP) sachets were placed into one half of the bags at each incubation temperature, while the other half of the bags served as a controls. Ethylene concentrations inside the bags were monitored at 12, 24, 48 and 72 h. The cuttings were placed on a propagation bench following 72 h of storage, and leaf abscission was recorded after 4 days in propagation. Leaf abscission increased in the control packages as temperature increased from 10 to 26°C, while 1-MCP reduced leaf abscission at 18 and 26°C. Thus, at 26°C 0.8 or 0.15 abscised leaves per cutting were monitored for control or 1-MCP-treated cuttings, respectively. The ethylene concentration measured at 48 h in the control packages increased from 0 to 0.5 ppm as the temperature increased from 10 to 26°C, while in the packages with 1-MCP it increased from 0 to 2.1 ppm with increasing temperature. Thus, while no ethylene was produced by the cuttings at 10°C, with or without 1-MCP, the presence of 1-MCP resulted in accumulation of significantly higher ethylene concentrations in the packages stored at 18 or 26°C. Our results suggest that 1-MCP sachets placed in packages of un-rooted poinsettia cuttings provide a viable means for reducing their leaf abscission following shipment of 72 h at non-optimal temperatures, in spite of the high ethylene levels accumulated in the packages under these conditions. However, these higher ethylene concentrations induced by the 1-MCP treatment may cause a concern if shipments are delayed and the efficacy of the 1-MCP decreases over that time.