บทคัดย่องานวิจัย

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Effects of temperature, elevated carbon dioxide and physiological age on internal and external lower oxygen limits of apple fruit.

Yearsley, C. W.; Banks, N. H.; Ganesh, S.;

Postharvest Horticulture Series - Department of Pomology, University of California Year: 1997 Issue: No. 16 Pages: 65-70 Ref: 7 ref.

1997

บทคัดย่อ

Effects of temperature, elevated carbon dioxide and physiological age on internal and external lower oxygen limits of apple fruit.

The optimum atmosphere for a crop, with respect to oxygen, lies just above the lower oxygen limit (LOL), at which maximum benefits in relation to fruit quality are achieved and below which fruit quality is compromised by fermentation. LOLs in this study were estimated on the basis of steady-state internal atmospheres (LOLis) since it is the internal O2 partial pressure, close to equilibrium with the cytosol, that mediates important physiological processes. Two types of LOLs were defined quantitatively: the anaerobic compensation point (ACP) and the fermentation threshold (FT). ACP was described in terms of plots of the internal CO2 vs. internal and external O2 partial pressures, and FT in terms of plots both of a measure of the respiratory quotient (RQi) and ethanol (EtOH) accumulation (FTiEtOH) vs. internal and external O2 partial pressures. Temperature (0 deg -28 deg C) had little effect on increasing LOLis of postclimacteric apples (cultivars Cox's Orange Pippin and Braeburn) except at temper

atures >28 deg . Values for FTiRQ and FTiEtOH tended to be higher than for ACPi. Similarly, LOLis were relatively constant with respect to elevated peCO2 (0 to 8 kPa at 0 deg and 20 deg ) and physiological age (preclimacteric, climacteric or postclimacteric fruits at 0 deg or 20 deg ). In contrast, ACPes increased markedly with temperature, and the increase was greater for fruits with low skin permeance to O2 and CO2 such as Braeburn. High intra- and intercultivar variability in skin permeance means that LOLis, and in particular the FT, should provide the safest estimate of the true LOL of a population of apples.