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Exposure to O�C for 4 weeks caused a threefold increase in cell membrnno permeability of mature-green tomato fruits (susceptible to chilling injury) hut had no effect on that of cabbage leaves (not susceptible). While tomato fruits chilled for 12 days lost two-thirds of their capacity to esterify phosphate at 20�0, a steady rise in this capacity occurred during chilling of cabbage leaves for 5 weeks. In tomato fruits the rate of phosphate esterification at the chilling temperature fell in 12 days to about one-half of the rate at the commencement of chilling .. It is suggested that the characteristic symptoms of chilling injury in mature-green tomato fruits, viz. increased susceptibility to fungal attack and loss of the capacity to ripen normally. may result from an energy deficit caused by a chilling. induced reduction in the phosphorylative capacity of the tissue.

This study establishes the rate a1-nd pattern of ethylene production by ripening tomato fruits (Lycopersicum esculen tum MIiller) and relates this to respiration (carbon dioxide evolution) and the stage of ripeness as shown by red color development. The influence of the harvest date has been investigated, since the changing environmental conditions encountered during a harvest season might influence the ethylene producing ability of the fruit and hence its ability to ripen properly late in the season. It has been shown by other workers that the keeping quality of various varieties of apples (9, 12) and pears (8) can be correlated with their ethylene producing ability.The identification and measurement of ethylene in the emanations of ripening fruits has been considered in recent reviews (1,13,15,16) and in a survey of many subtropical and semitropical species (2). The rate of ethylene production varies among species and among varieties of the same species, both in mnagnitude and in the nature of the patterns displayed. Biale (1) has stressed the need to search for relations of ethylene production to respiration and storage life of fruits.The following bioassays have been used to show that tomato fruits produce an active emanation: Stimulation of fruit ripening, epinasty of potato ancI tomato leaves, "sleepiness" of carnation flowers, and the triple response of etiolated pea seedlings (5,6,7,10,11,14). These responses are generally agreed to be due to ethylene production b-the fruit tissues. Although direct chemical identification of ethylene as a volatile product of tomatoes has not been reported, selective quantitative methods have been applied. Christensen, Hansen, and Cheldelin (3) used their microbromination method to determine the ethylene content of a ripe tomato fruit anid found 0.01 ml/

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