リンゴ‘千秋’果実の収穫熟度による低温障害感受性, 呼吸活性一びにエチレン生成の差異

Abstract

Changes in respiratory rate and ethylene production in ‘Sensyu’ apple fruit, and electrolyte leakage from flesh tissue during storage were investigated in relation to fruit maturity and chilling sensitivity. Fruits were harvested at early maturity (pre-climacteric), standard maturity (climacteric) and late maturity (post-climacteric).1. During storage, the rates of respiration and ethylene production were greatly reduced at -1°, 0° or 5°C compared to 20°C. After transfer from the chilling temperature (-1° to 5°C) to 20°C, fruits harvested at the same maturity showed nearly the same pattern of changes in respiratory rate and ethylene production.2. When apple fruits were stored at 20°, 5°, 0° or -1°C, ethylene-forming enzyme (EFE) activity increased rapidly in proportion to the increase in storage temperature, excepting for the early-harvested fruits. In these fruits, the increase of EFE activity of fruits stored at 0°C was faster than in fruits stored at 5°C.3. During storage at 20°C, fruit softening and rotting were markedly observed in the fruits of standard and late harvest as compared with the early-harvested ones. On the other hand, the development of chilling injury symptoms was severe in the early-harvested fruits, while slight pitting occurred in the fruits of standard and late harvest during storage at 0° or -1°C. It could be suggested that storage temperature at 5°C would be available for the early-harvested fruits, while for the fruits of standard and late harvest it would be -1°C.4. The rate of electrolyte leakage from flesh tissue on the first inspection of the fruits just harvested was low in the early-maturity fruits, which showed high chilling sensitivity. On the other hand, a marked increase in the rate of electrolyte leakage occurred in the early-harvested fruits during storage at 0° or -1°C, while almost no change was observed in the fruits of standard and late harvest.