Interplay of O2 and C2H4 on climacteric respiration.
Mir, N. A. and Beaudry, R. M.
ISHS Acta Horticulturae 553: 651-655.
2001
บทคัดย่อ
Respiratory curves describing the dependence of O2 uptake on O2 were obtained for slicing and 'Roma'-type tomato, and 'Jonathan' and 'Empire' apple fruits at 20 deg C, for ripening fruit and for mature, non-ripening fruit. Mature, non-ripening fruits were maintained in that state by the application of 1-methylcyclopropene (1-MCP) or the use of a non-ripening mutant in the case of tomato. The range of O2 atmospheres wherein the reduction of O2 relative to ambient yielded a significant (50%) reduction in respiration relative to the maximum rate of respiration, but was above the fermentation threshold, was termed the 'safe working atmosphere' (SWA). For apple, there was no SWA for non-ripening apple fruits since a 50% reduction in respiration occurred at the fermentation threshold. During ripening, the respiratory curve shifted, revealing a marked increase in the apparent Km and maximum rate of respiration, with no change in the fermentation threshold, resulting in the creation of a SWA between 2.5 and 9 kPa O2. A similar, less dramatic, shift in the respiratory curve for tomato fruit also occurred. In a flow-through system, low O2 reduced the rate of respiration of ethylene-insensitive tomato fruit by approximately 50% and resulted in an approximate doubling of the storability of the fruit. Insensitivity to ethylene yielded fruit with a respiratory rate approximately one-half that of ripening fruit, but storability was improved approximately five-fold. The data collectively suggest that inhibition of ethylene action by low O2, rather than a reduction in global metabolism via inhibition of respiration, is the key to preserving quality. Climacteric fruit tend to be more responsive than non-climacteric fruit to inhibition of respiration by low O2, after ripening has commenced.