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A role for ethylene in the yellowing of broccoli after harvest.

Tian, M. S.; Downs, C. G.; Lill, R. E.; King, G. A.;

Journal of the American Society for Horticultural Science Year: 1994 Vol: 119 Issue: 2 Pages: 276-281 Ref: 20 ref.

1994

บทคัดย่อ

A role for ethylene in the yellowing of broccoli after harvest.

ABSTRACT :

 

Ethylene production from harvested broccoli cv. Shogun florets stored at 20 deg C in darkness increased as the sepal tissues yellowed. The pattern of respiration rate and ethylene production from branchlets or entire heads was similar, although the magnitude of ethylene and carbon dioxide production appeared to be diluted by the other fleshy stem tissues. Removing the reproductive structures (stamens and pistil) from florets reduced the yellowing rate. The pistil and stamens also had 7-fold higher levels of ACC oxidase activity and more than double the ethylene production of other tissues within the floret. Stamen ACC oxidase activity was high on the first day after harvest, before yellowing became obvious. Changes in ACC oxidase activity of the pistil and stamens mirrored changes in ACC content in these tissues. The climacteric status of broccoli was confirmed by exposure to 0.5% propylene, which stimulated respiration and ethylene production and accelerated yellowing (measured as chlorophyll a

nd hue-angle decline), confirming the climacteric status of harvested broccoli. Broccoli tissues did not respond to propylene immediately after harvest. In tissues aged in air before treatment, the time for response to propylene was shorter, suggesting a change in tissue sensitivity. Ethylene exposure induced a rate-dependent decline in hue angle, with 1 p.p.m. ethylene giving the maximum response.