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- Author or Editor: Reinosuke Nakamura x
- Journal of the American Society for Horticultural Science x
Abstract
A numerical expression for the minimum treatment time (MTT) for ethylene necessary to induce ripening in banana [Musa (AAA group, Cavendish subgroup) ‘Giant Cavendish’] fruit was determined using the concentration of applied ethylene, fruit temperature, and a number of fruit variables. The content of sugars, organic acids and ACC, and the activity of the ethylene-forming enzyme (EFE) in the fruit just prior to ethylene treatment were measured as fruit variables. In a linear regression analysis between MTT determined at 30°C with 1000 μl·liter−1 ethylene and each fruit variable, significant correlations were found with ACC (r = −0.84) and individual sugar content. MTT (y hours) in banana fruit treated with a selected ethylene concentration (x μl·liter−1) at a given temperature (t °C) could be estimated from their initial ACC content (k nmol·g−1) by the following equation: y = (0.202 − 0.238k)t2 − (11.92 − 13.1k)t + 185.8 − 190.7k − (0.02t2 − 1.3t + 22)log10x. When the calculated values for MTT were compared with the observed values, this equation adequately represented the MTT for Japanese commercial bananas. Chemical name used: 1-aminocydopropane-1-carboxylic acid (ACC).
The respiration rate (O2 uptake) and the rate of C2H4. production were measured before, during, and after 24 hours of treatment with 60% CO2 (20% O2) in 18 kinds of fruits and vegetables by use of an automated system connected to a microcomputer. High CO2 decreased respiration only in climacteric fruit and broccoli, which were producing C2H4. Ethylene production decreased with CO, treatment of peaches, tomatoes, and broccoli, but that of bananas increased. In five nonclimacteric fruits (three citrus species, grapes, and Japanese pears) and several vegetables (carrots, onions, cauliflower, and cabbage), in which C2H4 production was not detected, high CO2 affected respiration little, if at all. When eggplants, cucumbers, podded peas, spinach, and lettuce were treated with high CO2, C2H4 production began and respiration increased. These results indicate that the respiratory responses of harvested horticultural crops to high CO2 might be mediated by the effects of CO2 on the action and/or synthesis of C2H4.