|CLARK J R|
|COLLINS J K|
Submitted to: Postharvest International Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/1/1995
Publication Date: N/A
Interpretive Summary: Little is known about the ripening of blackberry fruit. Fruit of the erect cultivar 'Navaho' were harvested at green through dull black (overripe) stages to determine changes occurring during ripening. Blackberry fruit grow rapidly early in development and after fruit start to turn black. Changes in fruit firmness occurred just before acidity de- creased. Ethylene production in fruit was not detected until the very las stages of ripeness. The ability of fruit to produce low levels of ethylene was present at all stages of ripeness. Results indicate that blackberry fruit exhibit distinct changes during ripening, but the relationship between ethylene and ripening is not clear.
Technical Abstract: Fruit were harvested from 'Navaho', an erect, thornless blackberry (Rubus sp.) cultivar, to study ripening. Fruit growth, measured as fresh and dry weights, was double sigmoidal, like other stone fruits. Ethylene production did not peak until the dull black (overripe) stage of maturity, and did not exceed 0.4 nl/g-h. Free 1-aminocyclopropane-1-carboxylic acid (ACC) and ACC oxidase did not increase until the shiny black stage, corresponding with the first detectable ethylene production. Skin and receptacle firmness decreased greatly between the mottled (part black) and shiny black stages of ripeness; the rate of softening was greater in receptacle tissue. Levels of ACC oxidase activity decreased in the skin tissue (7 to 2 nl/g-h) and increased in the receptacle tissue (25 to 60 nl/g-h) as fruit changed from red (unripe) to dull black (overripe). These results indicate that ripening in blackberry fruit occurs first in the receptacle tissue.