ETHYLENE-INDUCED GROWTH OF PETALS AND STYLES IN THE IMMATURE CARNATION INFLORESCENCE

Flowering stems of ''White Sim'' glasshouse carnations were cut when the corolla protruded about 5.0 mm above the calyx and were treated with about 10 vpm [volumes per million] ethylene for 24 h in closed chambers or a free-flow system. Petals elongated and the infloresence (plus stem) gained fresh weight; the styles also elongated, increased their fresh weight but became visibly thinner than the untreated controls. Measurement of cell dimensions indicated that part of the growth was due to increased cell elongation in the basal part of the petal. These observations are discussed in relation to the very different response of the mature flower to ethylene.