The Production of Ethylene by Whole Apple Fruits and by Tissue 1

It is shown that the production of ethylene by whole apples, discs of peel prepared from them, and extracts prepared from the discs and supplied with linolenic acid, increases simultaneously during the development of the respiration climacteric in apples. As the climacteric peak is reached, the ability of the extracts to produce ethylene declines and this is associated with a rapid loss of ethylene-producing activity on short term (up to 24 h) ageing of the peel discs from which the extracts were obtained. It is suggested that the gmn.ll ethylene production by extracts (with linolenic acid) from pre-climacteric fruits, which are not themselves evolving sufficient ethylene for its detection in the ambient atmosphere, may be explained on the grounds that even before the climacterio the fruit is producing small amounts of ethylene within the tissue; the tissue, as the climacteric phase is approached, becomes more sensitive to ethylene and autocatalysed production of the gas then stimulates the fruit into the respiration climacteric.