Ethylene production by three lily species and their response to ethylene exposure

Several lily cultivars from the three main groups were screened for response to ethylene. The vase life of most Oriental hybrid and Lilium longiflorum cultivars was unaffected by ethylene exposure. However, some Asiatic hybrids showed minor responses, as noted for cultivars ‘Apeldoorn’, ‘Goldena’, ‘Elite’ and ‘Mona’. Endogenous ethylene production by all lily cultivars tested was close to or below the limits of detection. CO2 production rates during vase life of 7 days at 20°C varied from 0.5–1.5 μmol kg−1 s−1, with Asiatic hybrids having rates in the upper end of the range. No climacteric increase in ethylene or CO2 production was detected during 7 days at 20°C. Vase life of two Asiatic hybrids (‘Cordelia’ and ‘Prato’) was not affected by a wide range of ethylene concentrations for varying durations, except at the highest concentration and duration of ethylene exposure tested, when vase life was reduced by only about 10–20%. For those Asiatic lily cultivars responding to ethylene exposure, the main effects were caused by high ethylene levels, with a reduced degree of flower opening and percentage of buds which opened. Both these factors influence vase life determination of stems, although quality of the individual flower buds was often less affected by ethylene exposure, as evidenced by similar or extended display life (the period flowers are open and of optimum quality) in ethylene-treated flowers. Pre-treatment of stems with Chrysal® or silver thiosulphate (STS) had little effect on the vase life of flowers subsequently exposed to ethylene. Pre-treatment with 1-methylcyclopropene (1-MCP) did not generally extend the vase life or improve flower quality of the Asiatic or L. longiflorum cultivars tested, although exposure to ethylene did reduce vase life of ‘Elite’ and ‘Cordelia’ by 1.5 days compared with flowers pre-treated with 1-MCP. For ‘Cordelia’, in vivo 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase activity was high, indicating that the enzymatic machinery for ethylene production is present even although endogenous levels were difficult to detect. Generally, ethylene exposure had little effect on cut flower quality or senescence of many of the lily cultivars examined, even when present at high concentrations. This is at variance with industry recommendations that lily flowers be treated with an ethylene antagonist prior to presentation at auction.